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Find video protocols related to scientific articles indexed in Pubmed.
Cognitive impairment and resting-state network connectivity in Parkinson's disease.
Hum Brain Mapp
PUBLISHED: 08-28-2014
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The purpose of this work was to evaluate changes in the connectivity patterns of a set of cognitively relevant, dynamically interrelated brain networks in association with cognitive deficits in Parkinson's disease (PD) using resting-state functional MRI. Sixty-five nondemented PD patients and 36 matched healthy controls were included. Thirty-four percent of PD patients were classified as having mild cognitive impairment (MCI) based on performance in attention/executive, visuospatial/visuoperceptual (VS/VP) and memory functions. A data-driven approach using independent component analysis (ICA) was used to identify the default-mode network (DMN), the dorsal attention network (DAN) and the bilateral frontoparietal networks (FPN), which were compared between groups using a dual-regression approach controlling for gray matter atrophy. Additional seed-based analyses using a priori defined regions of interest were used to characterize local changes in intranetwork and internetwork connectivity. Structural group comparisons through voxel-based morphometry and cortical thickness were additionally performed to assess associated gray matter atrophy. ICA results revealed reduced connectivity between the DAN and right frontoinsular regions in MCI patients, associated with worse performance in attention/executive functions. The DMN displayed increased connectivity with medial and lateral occipito-parietal regions in MCI patients, associated with worse VS/VP performance, and with occipital reductions in cortical thickness. In line with data-driven results, seed-based analyses mainly revealed reduced within-DAN, within-DMN and DAN-FPN connectivity, as well as loss of normal DAN-DMN anticorrelation in MCI patients. Our findings demonstrate differential connectivity changes affecting the networks evaluated, which we hypothesize to be related to the pathophysiological bases of different types of cognitive impairment in PD. Hum Brain Mapp, 2014. © 2014 Wiley Periodicals, Inc.
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Correlates of cerebrospinal fluid levels of oligomeric- and total-?-synuclein in premotor, motor and dementia stages of Parkinson's disease.
J. Neurol.
PUBLISHED: 07-04-2014
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High-oligomeric and low-total-?-synuclein cerebrospinal fluid (CSF) levels have been found in Parkinson's disease (PD), but with inconsistent or limited data, particularly on their clinical and structural correlates in earliest (premotor) or latest (dementia) PD stages. We determined CSF oligomeric- and total-?-synuclein in 77 subjects: 23 with idiopathic REM-sleep behaviour disorder (iRBD, a condition likely to include a remarkable proportion of subjects in the premotor stage of PD) and 41 with PD [21 non-demented (PDND) + 20 demented (PDD)], intended to reflect the premotor-motor-dementia PD continuum, along with 13 healthy controls. The study protocol also included the Unified PD Rating Scale motor-section (UPDRS-III), mini mental state examination (MMSE), neuropsychological cognitive testing, 3T brain MRI for cortical-thickness analyses, CSF ? and CSF A?. CSF oligomeric-?-synuclein was higher in PDND than iRBD and in PDD than iRBD and controls, and correlated with UPDRS-III, MMSE, semantic fluency and visuo-perceptive scores across the proposed premotor-motor-dementia PD continuum (iRBD + PDND + PDD). CSF total-?-synuclein positively correlated with age, CSF A?, and, particularly, CSF ?, tending towards lower levels in PD (but not iRBD) vs. controls only when controlling for CSF ?. Low CSF total-?-synuclein was associated with dysfunction in phonetic-fluency (a frontal-lobe function) in PD and with frontal cortical thinning in iRBD and PDND independently of CSF ?. Conversely, the associations of high (instead of low) CSF total-?-synuclein with posterior-cortical neuropsychological deficits in PD and with posterior cortical thinning in PDD were driven by high CSF ?. These findings suggest that CSF oligomeric- and total-?-synuclein have different clinical, neuropsychological and MRI correlates across the proposed premotor-motor-dementia PD continuum. CSF total-?-synuclein correlations with CSF ? and A? support the hypothesis of an interaction among these proteins in PD, with CSF ? probably influencing the presence of high (instead of low) CSF total-?-synuclein and its correlates mostly in the setting of PD-related dementia.
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Changes in whole-brain functional networks and memory performance in aging.
Neurobiol. Aging
PUBLISHED: 03-27-2014
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We used resting-functional magnetic resonance imaging data from 98 healthy older adults to analyze how local and global measures of functional brain connectivity are affected by age, and whether they are related to differences in memory performance. Whole-brain networks were created individually by parcellating the brain into 90 cerebral regions and obtaining pairwise connectivity. First, we studied age-associations in interregional connectivity and their relationship with the length of the connections. Aging was associated with less connectivity in the long-range connections of fronto-parietal and fronto-occipital systems and with higher connectivity of the short-range connections within frontal, parietal, and occipital lobes. We also used the graph theory to measure functional integration and segregation. The pattern of the overall age-related correlations presented positive correlations of average minimum path length (r = 0.380, p = 0.008) and of global clustering coefficients (r = 0.454, p < 0.001), leading to less integrated and more segregated global networks. Main correlations in clustering coefficients were located in the frontal and parietal lobes. Higher clustering coefficients of some areas were related to lower performance in verbal and visual memory functions. In conclusion, we found that older participants showed lower connectivity of long-range connections together with higher functional segregation of these same connections, which appeared to indicate a more local clustering of information processing. Higher local clustering in older participants was negatively related to memory performance.
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Cortical thinning associated with mild cognitive impairment in Parkinson's disease.
Mov. Disord.
PUBLISHED: 03-17-2014
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The aim of this study was to investigate patterns of cortical atrophy associated with mild cognitive impairment in a large sample of nondemented Parkinson's disease (PD) patients, and its relation with specific neuropsychological deficits. Magnetic resonance imaging (MRI) and neuropsychological assessment were performed in a sample of 90 nondemented PD patients and 32 healthy controls. All underwent a neuropsychological battery including tests that assess different cognitive domains: attention and working memory, executive functions, memory, language, and visuoperceptual-visuospatial functions. Patients were classified according to their cognitive status as PD patients without mild cognitive impairment (MCI; n?=?43) and PD patients with MCI (n?=?47). Freesurfer software was used to obtain maps of cortical thickness for group comparisons and correlation with neuropsychological performance. Patients with MCI showed regional cortical thinning in parietotemporal regions, increased global atrophy (global cortical thinning, total gray matter volume reduction, and ventricular enlargement), as well as significant cognitive impairment in memory, executive, and visuospatial and visuoperceptual domains. Correlation analyses showed that all neuropsychological tests were associated with cortical thinning in parietotemporal regions and to a lesser extent in frontal regions. These results provide neuroanatomic support to the concept of MCI classified according to Movement Disorders Society criteria. The posterior pattern of atrophy in temporoparietal regions could be a structural neuroimaging marker of cognitive impairment in nondemented PD patients. All of the neuropsychological tests reflected regional brain atrophy, but no specific patterns were seen corresponding to impairment in distinct cognitive domains.
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Effects of cross-sex hormone treatment on cortical thickness in transsexual individuals.
J Sex Med
PUBLISHED: 03-11-2014
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Untreated transsexuals have a brain cortical phenotype. Cross-sex hormone treatments are used to masculinize or feminize the bodies of female-to-male (FtMs) or male-to-female (MtFs) transsexuals, respectively.
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The interaction effect between BDNF val66met polymorphism and obesity on executive functions and frontal structure.
Am. J. Med. Genet. B Neuropsychiatr. Genet.
PUBLISHED: 02-19-2014
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The prevalence of obesity is increasing worldwide. Previous research has shown a relationship between obesity and both executive functioning alterations and frontal cortex volume reductions. The Brain Derived Neurotrophic Factor val66met polymorphism, involved in eating behavior, has also been associated with executive functions and prefrontal cortex volume, but to date it has not been studied in relation to obesity. Our aim is to elucidate whether the interaction between the Brain Derived Neurotrophic Factor val66met polymorphism and obesity status influences executive performance and frontal-subcortical brain structure. Sixty-one volunteers, 34 obese and 27 controls, age range 12-40, participated in the study. Participants were assigned to one of two genotype groups (met allele carriers, n?=?16, or non-carriers, n?=?45). Neuropsychological assessment comprised the Trail Making Test, the Stroop Test and the Wisconsin Card Sorting Test, all tasks that require response inhibition and cognitive flexibility. Subjects underwent magnetic resonance imaging in a Siemens TIM TRIO 3T scanner and images were analyzed using the FreeSurfer software. Analyses of covariance controlling for age and intelligence showed an effect of the obesity-by-genotype interaction on perseverative responses on the Wisconsin Card Sorting Test as well as on precentral and caudal middle frontal cortical thickness: obese met allele carriers showed more perseverations on the Wisconsin Card Sorting Test and lower frontal thickness than obese non-carriers and controls. In conclusion, the Brain Derived Neurotrophic Factor may play an important role in executive functioning and frontal brain structure in obesity.
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Functional brain networks and cognitive deficits in Parkinson's disease.
Hum Brain Mapp
PUBLISHED: 01-10-2014
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Graph-theoretical analyses of functional networks obtained with resting-state functional magnetic resonance imaging (fMRI) have recently proven to be a useful approach for the study of the substrates underlying cognitive deficits in different diseases. We used this technique to investigate whether cognitive deficits in Parkinson's disease (PD) are associated with changes in global and local network measures. Thirty-six healthy controls (HC) and 66 PD patients matched for age, sex, and education were classified as having mild cognitive impairment (MCI) or not based on performance in the three mainly affected cognitive domains in PD: attention/executive, visuospatial/visuoperceptual (VS/VP), and declarative memory. Resting-state fMRI and graph theory analyses were used to evaluate network measures. We have found that patients with MCI had connectivity reductions predominantly affecting long-range connections as well as increased local interconnectedness manifested as higher measures of clustering, small-worldness, and modularity. The latter measures also tended to correlate negatively with cognitive performance in VS/VP and memory functions. Hub structure was also reorganized: normal hubs displayed reduced centrality and degree in MCI PD patients. Our study indicates that the topological properties of brain networks are changed in PD patients with cognitive deficits. Our findings provide novel data regarding the functional substrate of cognitive impairment in PD, which may prove to have value as a prognostic marker.
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Decreased Default Mode Network connectivity correlates with age-associated structural and cognitive changes.
Front Aging Neurosci
PUBLISHED: 01-01-2014
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Ageing entails cognitive and motor decline as well as brain changes such as loss of gray (GM) and white matter (WM) integrity, neurovascular and functional connectivity alterations. Regarding connectivity, reduced resting-state fMRI connectivity between anterior and posterior nodes of the Default Mode Network (DMN) relates to cognitive function and has been postulated to be a hallmark of ageing. However, the relationship between age-related connectivity changes and other neuroimaging-based measures in ageing is fragmentarily investigated. In a sample of 116 healthy elders we aimed to study the relationship between antero-posterior DMN connectivity and measures of WM integrity, GM integrity and cerebral blood flow (CBF), assessed with an arterial spin labeling sequence. First, we replicated previous findings demonstrating DMN connectivity decreases in ageing and an association between antero-posterior DMN connectivity and memory scores. The results showed that the functional connectivity between posterior midline structures and the medial prefrontal cortex was related to measures of WM and GM integrity but not to CBF. Gray and WM correlates of anterio-posterior DMN connectivity included, but were not limited to, DMN areas and cingulum bundle. These results resembled patterns of age-related vulnerability which was studied by comparing the correlates of antero-posterior DMN with age-effect maps. These age-effect maps were obtained after performing an independent analysis with a second sample including both young and old subjects. We argue that antero-posterior connectivity might be a sensitive measure of brain ageing over the brain. By using a comprehensive approach, the results provide valuable knowledge that may shed further light on DMN connectivity dysfunctions in ageing.
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Brain activation during speech perception in a patient with a massive left hemisphere infarction.
Brain Inj
PUBLISHED: 10-08-2013
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Little is known about the regions involved in recovery from global aphasia in patients with malignant infarction after decompressive hemicraniectomy. This study reports a case of brain activation during speech perception in a right-handed patient with a massive left hemispheric infarction.
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White matter/gray matter contrast changes in chronic and diffuse traumatic brain injury.
J. Neurotrauma
PUBLISHED: 10-01-2013
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Abstract Signal-intensity contrast of T1-weighted magnetic resonance imaging scans has been associated with tissue integrity and reported as a sign of neurodegenerative changes in diseases such as Alzheimers disease. After severe traumatic brain injury (TBI), progressive structural changes occur in white (WM) and gray matter (GM). In the current study, we assessed the signal-intensity contrast of GM and WM in patients with diffuse TBI in the chronic stage to (1) characterize the regional pattern of WM/GM changes in intensity contrast associated with traumatic axonal injury, (2) evaluate possible associations between this measure and diffusion tensor image (DTI)/fractional anisotropy (FA) for detecting WM damage, and (3) investigate the correlates of both measures with cognitive outcomes. Structural T1 scans were processed with FreeSurfer software to identify the boundary and calculate the WM/GM contrast maps. DTIs were processed with the FMRIB software library to obtain FA maps. The WM/GM contrast in TBI patients showed a pattern of reduction in almost all of the brain, except the visual and motor primary regions. Global FA values obtained from DTI correlated with the intensity contrast of all associative cerebral regions. WM/GM contrast correlated with memory functions, whereas FA global values correlated with tests measuring memory and mental processing speed. In conclusion, tissue-contrast intensity is a very sensitive measure for detecting structural brain damage in chronic, severe and diffuse TBI, but is less sensitive than FA for reflecting neuropsychological sequelae, such as impaired mental processing speed.
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Does verbal and gestural expression ability predict comprehension ability in cerebral palsy?
Percept Mot Skills
PUBLISHED: 09-17-2013
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Some people with cerebral palsy have motor and associated impairments that may hinder verbal and gestural expression to various extents. This study explores whether the ability to produce verbal or gestural expressions may be related to the comprehension of verbal communications and gestures. The influence of severity of motor impairment, general cognitive performance, and age on comprehension ability was also explored. Forty people with cerebral palsy were assigned to different groups according to their verbal and gestural expression abilities. A neuropsychological assessment of comprehension abilities and general cognitive performance was carried out. Multiple linear regression analysis was applied to identify the possible influence of expression abilities on comprehension abilities and also to detect the possible contribution of severity of motor impairment, general cognitive performance, and age. Results indicate that verbal and gestural comprehension was mainly predicted by general cognitive performance. Severity of motor impairment and age did not contribute to predicting comprehension abilities. Only verbal grammar comprehension was significantly predicted by verbal expression ability. Verbal expression ability may be an important marker for cerebral palsy therapies. In non-ambulant patients with bilateral cerebral palsy, impaired gestural expression should not be taken as an indicator of impaired gestural comprehension.
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Regional vulnerability of hippocampal subfields to aging measured by structural and diffusion MRI.
Hippocampus
PUBLISHED: 07-18-2013
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In the past few years, there has been an increasing awareness of the regional vulnerability of the hippocampus to age-related processes. However, to date, no studies have assessed the effects of age on different structural magnetic resonance parameters in the specific hippocampal subfields. In this study, we measured volume, mean diffusivity (MD) and fractional anisotropy (FA) in the presubiculum, subiculum, fimbria, cornu ammonis (CA) 1,2-3,4-DG and the whole hippocampus in fifty cognitively intact elder adults between 50 and 75 years of age (20 men, 30 women). Segmentation of hippocampal subfields was performed using FreeSurfer. Individual MD and FA images were coregistered to T1-weighted volumes using FLIRT of FSL. Linear regression analyses were performed to assess the effects of age on the anatomical measures of each subfield. In addition, multiple regression analyses were also carried out to assess which of the anatomical measures that showed a correlation with age in the previous analyses, were the best age predictors in the hippocampus. In agreement with previous studies, our results showed a significant association between age and volume (P?
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Frontal cortical thinning and subcortical volume reductions in early adulthood obesity.
Psychiatry Res
PUBLISHED: 06-05-2013
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Obesity depends on homeostatic and hedonic food intake behavior, mediated by brain plasticity changes in cortical and subcortical structures. The aim of this study was to investigate cortical thickness and subcortical volumes of regions related to food intake behavior in a healthy young adult sample with obesity. Thirty-seven volunteers, 19 with obesity (age=33.7±5.7 (20-39) years body-mass index (BMI)=36.08±5.92 (30.10-49.69)kg/m(2)) and 18 controls (age=32.3±5.9 (21-40) years; BMI=22.54±1.94 (19.53-24.97)kg/m(2)) participated in the study. Patients with neuropsychiatric or biomedical disorders were excluded. We used FreeSurfer software to analyze structural magnetic resonance images (MRI) and obtain global brain measures, cortical thickness and subcortical volume estimations. Finally, correlation analyses were performed for brain structure data and obesity measures. There were no between-group differences in age, gender, intelligence or education. Results showed cortical thickness reductions in obesity in the left superior frontal and right medial orbitofrontal cortex. In addition, the obesity group had lower ventral diencephalon and brainstem volumes than controls, while there were no differences in any other subcortical structure. There were no statistically significant correlations between brain structure and obesity measures. Overall, our work provides evidence of the structural brain characteristics associated with metabolically normal obesity. We found reductions in cortical thickness, ventral diencephalon and brainstem volumes in areas that have been implicated in food intake behavior.
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Inferior frontal and insular cortical thinning is related to dysfunctional brain activation/deactivation during working memory task in schizophrenic patients.
Psychiatry Res
PUBLISHED: 05-27-2013
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Although working memory is known to be impaired in schizophrenia the anatomical and functional relationships underlying this deficit remain to be elucidated. A combined imaging approach involving functional and structural magnetic resonance techniques was used, applying independent component analysis and surface-based morphometry to 14 patients with schizophrenia and 14 healthy controls. Neurocognitive functioning was assessed by a neuropsychological test battery that measured executive function. It was hypothesized that working memory dysfunctional connectivity in schizophrenia is related to underlying anatomical abnormalities. Patients with schizophrenia showed cortical thinning in the left inferior frontal gyrus and insula, which explained 57% of blood oxygenation level-dependent signal magnitude in functional magnetic resonance imaging in the central executive network (lateral prefrontal and parietal cortex) over-activation and default mode network (anterior and posterior cingulate) deactivation. No structure-function relationship emerged in the healthy control group. The study provides evidence to suggest that dysfunctional activation/deactivation patterns in schizophrenia may be explained in terms of underlying gray matter deficits.
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Differential vulnerability of gray matter and white matter to intrauterine growth restriction in preterm infants at 12 months corrected age.
Brain Res.
PUBLISHED: 05-24-2013
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Intrauterine growth restriction (IUGR) is associated with a high risk of abnormal neurodevelopment. Underlying neuroanatomical substrates are partially documented. We hypothesized that at 12 months preterm infants would evidence specific white-matter microstructure alterations and gray-matter differences induced by severe IUGR. Twenty preterm infants with IUGR (26-34 weeks of gestation) were compared with 20 term-born infants and 20 appropriate for gestational age preterm infants of similar gestational age. Preterm groups showed no evidence of brain abnormalities. At 12 months, infants were scanned sleeping naturally. Gray-matter volumes were studied with voxel-based morphometry. White-matter microstructure was examined using tract-based spatial statistics. The relationship between diffusivity indices in white matter, gray matter volumes, and perinatal data was also investigated. Gray-matter decrements attributable to IUGR comprised amygdala, basal ganglia, thalamus and insula bilaterally, left occipital and parietal lobes, and right perirolandic area. Gray-matter volumes positively correlated with birth weight exclusively. Preterm infants had reduced FA in the corpus callosum, and increased FA in the anterior corona radiata. Additionally, IUGR infants had increased FA in the forceps minor, internal and external capsules, uncinate and fronto-occipital white matter tracts. Increased axial diffusivity was observed in several white matter tracts. Fractional anisotropy positively correlated with birth weight and gestational age at birth. These data suggest that IUGR differentially affects gray and white matter development preferentially affecting gray matter. At 12 months IUGR is associated with a specific set of structural gray-matter decrements. White matter follows an unusual developmental pattern, and is apparently affected by IUGR and prematurity combined.
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Resting-state functional magnetic resonance imaging activity and connectivity and cognitive outcome in traumatic brain injury.
JAMA Neurol
PUBLISHED: 05-22-2013
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The study of brain activity and connectivity at rest provides a unique opportunity for the investigation of the brain substrates of cognitive outcome after traumatic axonal injury. This knowledge may contribute to improve clinical management and rehabilitation programs.
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Cognitive decline is mediated by gray matter changes during middle age.
Neurobiol. Aging
PUBLISHED: 05-09-2013
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The present theoretical framework of Alzheimers disease proposes that pathophysiological changes occur 10-20 years before the diagnosis of dementia. We addressed the question of how age-related changes in gray matter mediate the cognitive performance during middle age. Eighty-two participants (40-50 years, ±2) were assessed with a comprehensive neuropsychological battery covering a broad spectrum of cognitive domains and components. Mediation effects were studied with hierarchical regression and bootstrapping analysis. Results showed that more vulnerable cognitive components were related to executive functioning and in a lesser degree to processing speed. Age-related differences in gray matter mainly involved the frontal lobes. Moreover, age-related differences in visuoconstructive, visuospatial functions, reaction time, and mental flexibility and executive control were mediated by several gray matter regions. It is important to increase the knowledge of the impact of brain changes on cognitive function during middle age. To define the early stages of the aging process may allow early detection of pathologic changes and therapeutic interventions.
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Regional vulnerability of hippocampal subfields and memory deficits in Parkinsons disease.
Hippocampus
PUBLISHED: 03-29-2013
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Neuropathological studies show the hippocampus is affected in Parkinsons disease (PD), with the second subfield of the cornu armonis (CA2) being the most involved. Our aims were to assess in vivo volumes of different hippocampal subfields in patients with PD with and without visual hallucinations using MRI and test their association with verbal learning and long-term recall. A total of 18 nondemented PD patients, 18 nondemented PD patients with visual hallucinations and 18 neurologically unimpaired elderly controls matched by age and gender were enrolled in this study. We assessed the volumes of seven hippocampal subfields on MRI, including the cornu armonis (CA) sectors, subiculum, presubiculum, and the dentate gyrus (DG) using a novel technique that enables automated volumetry. The CA2-3 and CA4-DG subfields were significantly smaller in both groups of patients, while the subiculum was only reduced in PD patients with visual hallucinations, compared to controls. Significant correlations were found between learning performance and CA2-3 as well as CA4-DG volumes in the whole patient sample. These data show there is regional atrophy of specific hippocampal subfields in PD, which is more severe and further extends to the subiculum in patients with visual hallucinations. Our findings indicate that learning deficits are associated with volume loss in subfields that act as input regions in the hippocampal circuit, suggesting that degeneration in these regions could be responsible for cognitive dysfunction in PD.
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Combined dementia-risk biomarkers in Parkinsons disease: a prospective longitudinal study.
Parkinsonism Relat. Disord.
PUBLISHED: 03-05-2013
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Neuropsychological (mostly posterior-cortical) deficits, quantitative magnetic resonance imaging (MRI) atrophy patterns, and low cerebrospinal fluid (CSF) levels of amyloid-? have been separately related to worsening cognition in Parkinsons disease (PD). However, these biomarkers have not been longitudinally assessed in combination as PD-dementia predictors. In this prospective longitudinal study, 27 non-demented PD patients underwent CSF, neuropsychological and 3-T brain-MRI studies at baseline and were re-assessed 18 months later in terms of progression to dementia (primary outcome) and longitudinal neuropsychological and cortical thickness changes (secondary outcomes). At follow-up 11 patients (41%) had progressed to dementia. Lower CSF amyloid-?, worse verbal learning, semantic fluency and visuoperceptual scores, and thinner superior-frontal/anterior cingulate and precentral regions were significant baseline dementia predictors in binary logistic regressions as quantitative and/or dichotomised traits. All participants without baseline biomarker abnormalities remained non-demented whereas all with abnormalities in each biomarker type progressed to dementia, with intermediate risk for those showing abnormalities in a single to two biomarker types (p = 0.006). Both the dementia-outcome and low baseline CSF amyloid-? were prospectively associated with limbic and posterior-cortical neuropsychological decline and frontal, limbic and posterior-cortical thinning from baseline to follow-up. These findings suggest that the combination of CSF amyloid-?, neuropsychological and cortical thickness biomarkers might provide a basis for dementia-risk stratification and progression monitoring in PD.
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Cortical thinning is associated with disease stages and dementia in Parkinsons disease.
J. Neurol. Neurosurg. Psychiatr.
PUBLISHED: 03-05-2013
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To investigate the pattern of cortical thinning in Parkinsons disease (PD) across different disease stages and to elucidate to what extent cortical thinning is related to cognitive impairment.
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Neuroanatomical correlates of olfactory loss in normal aged subjects.
Behav. Brain Res.
PUBLISHED: 02-07-2013
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In non-demented older persons, smell dysfunction, measured premortem, has been associated with postmortem brain degeneration similar to that of Alzheimers disease. We hypothesized that distinct measures of gray and white matter integrity evaluated through magnetic resonance imaging (MRI) techniques could detect degenerative changes associated with age-related olfactory dysfunction. High-resolution T1-weighted images and diffusion-tensor images (DTI) of 30 clinically healthy subjects aged 51-77 were acquired with a 3-Tesla MRI scanner. Odor identification performance was assessed by means of the University of Pennsylvania Smell Identification Test (UPSIT). UPSIT scores correlated with right amygdalar volume and bilateral perirhinal and entorhinal cortices gray matter volume. Olfactory performance also correlated with postcentral gyrus cortical thickness and with fractional anisotropy and mean diffusivity levels in the splenium of the corpus callosum and the superior longitudinal fasciculi. Our results suggest that age-related olfactory loss is accompanied by diffuse degenerative changes that might correspond to the preclinical stages of neurodegenerative processes.
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Brain effects of cognitive remediation therapy in schizophrenia: a structural and functional neuroimaging study.
Biol. Psychiatry
PUBLISHED: 01-13-2013
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Cognitive remediation therapy positively affects cognition and daily functioning in patients with schizophrenia. However, studies on the underlying neurobiological mechanisms of this treatment are scarce. The aim of the current study was to investigate functional and structural connectivity brain changes in schizophrenia patients after cognitive remediation therapy using a whole-brain approach that combined functional magnetic resonance imaging and diffusion tensor imaging.
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Neural correlates of cognitive impairment in schizophrenia.
Br J Psychiatry
PUBLISHED: 07-04-2011
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Cognitive impairment is an established feature of schizophrenia. However, little is known about its relationship to the structural and functional brain abnormalities that characterise the disorder. Aims To identify structural and/or functional brain abnormalities associated with schizophrenic cognitive impairment.
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Modulation of large-scale brain networks by transcranial direct current stimulation evidenced by resting-state functional MRI.
Brain Stimul
PUBLISHED: 04-26-2011
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Brain areas interact mutually to perform particular complex brain functions such as memory or language. Furthermore, under resting-state conditions several spatial patterns have been identified that resemble functional systems involved in cognitive functions. Among these, the default-mode network (DMN), which is consistently deactivated during task periods and is related to a variety of cognitive functions, has attracted most attention. In addition, in resting-state conditions some brain areas engaged in focused attention (such as the anticorrelated network, AN) show a strong negative correlation with DMN; as task demand increases, AN activity rises, and DMN activity falls.
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Cerebral basis of visual hallucinations in Parkinsons disease: structural and functional MRI studies.
J. Neurol. Sci.
PUBLISHED: 04-01-2011
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The presence of visual hallucinations (VH) is a significant predictor of dementia in Parkinsons disease (PD) and it is associated with a more rapid cognitive decline. Non-demented PD patients with VH present greater neuropsychological impairment than those without VH in domains such as verbal and visual memory, language comprehension, and visuospatial and visuoperceptive functions. Frontal dysfunction has also been described in PD with VH, including deficits in verbal fluency, sustained attention, and inhibition. In PD with VH, structural and functional abnormalities within the primary visual system and visual association areas, including ventral and dorsal pathways, have been reported. Structural MRI studies have shown that non-demented PD patients with VH present grey matter reduction in parieto-occipital areas and the hippocampal head. A follow-up study performed at a mean of 30 months revealed that unlike PD patients without VH, PD patients with VH frequently develop dementia associated with progressive atrophy in limbic, paralimbic and neocortical areas. Functional MRI (fMRI) studies have revealed altered activation in occipito-temporal and frontal areas in response to simple and complex visual stimuli in PD patients with VH, suggesting a marked impairment in bottom-up visual processing, as well as an attentional deficit in the pathophysiology of VH in PD.
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Brain structural MRI correlates of cognitive dysfunctions in Parkinsons disease.
J. Neurol. Sci.
PUBLISHED: 03-29-2011
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Cognitive dysfunction occurs at early stages of Parkinsons disease (PD). Initial studies reported that cognitive dysfunction in early PD only affected fronto-striatal circuits, provoking a marked executive dysfunction. Memory impairment in PD was thought to depend on a problem in retrieving stored information, therefore also reflecting a fronto-striatal dysfunction. However, there is increasing structural MRI evidence of medial temporal lobe atrophy in PD, which may be responsible for memory dysfunction. Other neuropsychological functions usually impaired in PD are semantic fluency, visuoperceptual and visuospatial functions, decision-making and recognition of facial emotions; and impairments in these functions are associated with cortical structural changes assessed by MRI. Overall, although the literature on the topic is scarce, there is increasing evidence of brain structural changes, detectable by MRI, which can explain the neuropsychological deficits early in the clinical disease course before dementia develops. In this review, we summarize the papers that have used structural MRI to study the neuroanatomical correlates of cognitive dysfunctions in PD.
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Gray matter volume decrements in preterm children with periventricular leukomalacia.
Pediatr. Res.
PUBLISHED: 03-10-2011
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Periventricular leukomalacia (PVL) is the prototypic lesion in the encephalopathy of prematurity. Although PVL is identified by targeting cerebral white matter (WM), neuropathological and MRI studies document gray matter (GM) loss in cortical and subcortical structures. This study aimed to investigate the distribution of GM changes in children with a history of premature birth and PVL. Voxel-based morphometry was used to examine regional GM abnormalities in 22 children with a history of preterm birth and PVL. Preterms with PVL were compared with 22 terms and 14 preterms without PVL of similar GA and birth weight. GM and WM global volumetric volumes were found to decrease in comparison with both control groups. Regional GM volume abnormalities were also found: compared with their term peers, preterm children with PVL showed several regions of GM reduction. Moreover, PVL differed from preterms without PVL in the medial temporal lobe bilaterally, thalamus bilaterally, and caudate nuclei bilaterally. In addition, in our preterm sample with PVL, birth weight showed a statistical significant correlation with decreased GM regions. In conclusion, the voxel-based morphometry methodology revealed that PVL per se does involve GM reductions.
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Brain connectivity during resting state and subsequent working memory task predicts behavioural performance.
Cortex
PUBLISHED: 03-09-2011
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Brain regions simultaneously activated during any cognitive process are functionally connected, forming large-scale networks. These functional networks can be examined during active conditions [i.e., task-functional magnetic resonance imaging (fMRI)] and also in passive states (resting-fMRI), where the default mode network (DMN) is the most widely investigated system. The role of the DMN remains unclear, although it is known to be responsible for the shift between resting and focused attention processing. There is also some evidence for its malleability in relation to previous experience. Here we investigated brain connectivity patterns in 16 healthy young subjects by using an n-back task with increasing levels of memory load within the fMRI context. Prior to this working memory (WM) task, participants were trained outside fMRI with a shortened test version. Immediately after, they underwent a resting-state fMRI acquisition followed by the full fMRI n-back test. We observed that the degree of intrinsic correlation within DMN and WM networks was maximal during the most demanding n-back condition (3-back). Furthermore, individuals showing a stronger negative correlation between the two networks under both conditions exhibited better behavioural performance. Interestingly, and despite the fact that we considered eight different resting-state fMRI networks previously identified in humans, only the connectivity within the posteromedial parts of the DMN (precuneus) prior to the fMRI n-back task predicted WM execution. Our results using a data-driven probabilistic approach for fMRI analysis provide the first evidence of a direct relationship between behavioural performance and the degree of negative correlation between the DMN and WM networks. They further suggest that in the context of expectancy for an imminent cognitive challenge, higher resting-state activity in the posteromedial parietal cortex may be related to increased attentional preparatory resources.
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Dysfunctions of cerebral networks precede recognition memory deficits in early Parkinsons disease.
Neuroimage
PUBLISHED: 03-09-2011
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We aimed to investigate changes in the verbal recognition memory network in patients with early Parkinsons disease (PD) without overt recognition memory alteration. Verbal recognition memory was assessed in 24 PD patients in early stages of the disease and a control group of 24 healthy subjects during fMRI data acquisition. Participants were presented with a list of 35 words before imaging, and later during fMRI scanning they were required to recognize these previously presented words. Both model-based (FEAT) and model-free (MELODIC) analyses of the fMRI data were carried out with FSL software. Memory was also assessed by means of Reys Auditory Verbal Learning Test (RAVLT). PD patients showed no difference in the fMRI recognition memory task and recognition memory assessed by the RAVLT compared to healthy controls. Model-based analysis did not show significant differences between groups. On the other hand, model-free analysis identified components that fitted the task-model and were common to all the participants, as well as components that differed between PD and healthy controls. PD patients showed decreased task-related activations in areas involved in the recognition memory network and decreased task-related deactivations in the default mode network in comparison with controls. In conclusion, model-free fMRI analysis detected alterations in functional cerebral networks involved in a verbal memory task in PD patients without evident recognition memory deficit.
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Diffusion tensor imaging differences relate to memory deficits in diffuse traumatic brain injury.
BMC Neurol
PUBLISHED: 02-23-2011
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Memory is one of the most impaired functions after traumatic brain injury (TBI). We used diffusion tensor imaging (DTI) to determine the structural basis of memory deficit. We correlated fractional anisotropy (FA) of the fasciculi connecting the main cerebral regions that are involved in declarative and working memory functions.
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Assessment of cortical degeneration in patients with Parkinsons disease by voxel-based morphometry, cortical folding, and cortical thickness.
Hum Brain Mapp
PUBLISHED: 01-17-2011
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Noninvasive brain imaging methods provide useful information on cerebral involution and degenerative processes. Here we assessed cortical degeneration in 20 nondemented patients with Parkinsons disease (PD) and 20 healthy controls using three quantitative neuroanatomical approaches: voxel-based morphometry (VBM), cortical folding (BrainVisa), and cortical thickness (FreeSurfer). We examined the relationship between global and regional gray matter (GM) volumes, sulcal indices, and thickness measures derived from the previous methods as well as their association with cognitive performance, age, severity of motor symptoms, and disease stage. VBM analyses showed GM volume reductions in the left temporal gyrus in patients compared with controls. Cortical folding measures revealed significant decreases in the left frontal and right collateral sulci in patients. Finally, analysis of cortical thickness showed widespread cortical thinning in right lateral occipital, parietal and left temporal, frontal, and premotor regions. We found that, in patients, all global anatomical measures correlated with age, while GM volume and cortical thickness significantly correlated with disease stage. In controls, a significant association was found between global GM volume and cortical folding with age. Overall these results suggest that the three different methods provide complementary and related information on neurodegenerative changes occurring in PD, however, surface-based measures of cortical folding and especially cortical thickness seem to be more sensitive than VBM to identify regional GM changes associated to PD.
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The microstructure of white matter in male to female transsexuals before cross-sex hormonal treatment. A DTI study.
J Psychiatr Res
PUBLISHED: 09-03-2010
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Diffusion tensor imaging (DTI) has been shown to be sensitive in detecting white matter differences between sexes. Before cross-sex hormone treatment female to male transsexuals (FtM) differ from females but not from males in several brain fibers. The purpose of this paper is to investigate whether white matter patterns in male to female (MtF) transsexuals before commencing cross-sex hormone treatment are also more similar to those of their biological sex or whether they are more similar to those of their gender identity.
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Combination of diffusion tensor and functional magnetic resonance imaging during recovery from the vegetative state.
BMC Neurol
PUBLISHED: 09-03-2010
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The rate of recovery from the vegetative state (VS) is low. Currently, little is known of the mechanisms and cerebral changes that accompany those relatively rare cases of good recovery. Here, we combined functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) to study the evolution of one VS patient at one month post-ictus and again twelve months later when he had recovered consciousness.
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Olfactory impairment in Parkinsons disease and white matter abnormalities in central olfactory areas: A voxel-based diffusion tensor imaging study.
Mov. Disord.
PUBLISHED: 07-30-2010
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Olfactory dysfunction is known to occur before the appearance of the classical motor signs in Parkinsons disease (PD) and diffusion tensor imaging (DTI) studies in PD have reported fractional anisotropy (FA) reductions in the early disease stages. We aimed to investigate the relationship between olfactory dysfunction and white matter (WM) FA of central olfactory areas in early PD. Twenty-four patients at Hoehn and Yahr stages I and II and 24 healthy controls matched by age, gender and years of education participated in this study. DTI was acquired at a 3 Tesla scanner and odor identification was assessed using the University of Pennsylvania Smell Identification Test (UPSIT). We performed FA voxelwise group comparisons in the central olfactory structures using tract-based spatial statistics (TBSS) and correlation analyses between FA values in these central olfactory areas and UPSIT scores. Patients with severe microsmia (UPSIT between 19 and 25) and anosmia (UPSIT lower or equal to 18) had lower FA values than PD patients with mild/moderate or no olfactory dysfunction (UPSIT between 26 and 40) and healthy controls in the WM adjacent to gyrus rectus. In addition, patients with anosmia had reduced FA in the WM surrounding primary olfactory areas in comparison with healthy controls. FA values in the WM adjacent to primary olfactory cortex and right gyrus rectus correlated with UPSIT scores in the PD group. This study demonstrates, for the first time, that microstructural WM reductions are present in the central olfactory system of early stage PD patients and that these reductions are associated with reduced ability to smell.
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White matter fractional anisotropy is related to processing speed in metabolic syndrome patients: a case-control study.
BMC Neurol
PUBLISHED: 07-27-2010
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Metabolic Syndrome (MetSd) is a cluster of vascular risk factors that may influence cerebrovascular pathology during aging. Recently, microstructural white matter (WM) changes detected by diffusion tensor imaging (DTI) and processing speed deficits have been reported in MetSd patients. We aimed to test the relationship between WM alteration and cognitive impairment in these patients.
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A cross-sectional and follow-up functional MRI study with a working memory task in adolescent anorexia nervosa.
Neuropsychologia
PUBLISHED: 04-26-2010
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Structural and functional brain abnormalities have been described in anorexia nervosa (AN). The objective of this study was to examine whether there is abnormal regional brain activation during a working memory task not associated with any emotional stimuli in adolescent patients with anorexia and to detect possible changes after weight recovery. Fourteen children and adolescents (age range 11-18 years) consecutively admitted with DSM-IV diagnosis of AN and fourteen control subjects of similar age were assessed by means of psychopathological scales and functional magnetic resonance imaging (fMRI) during a working memory task. After seven months of treatment and weight recovery, nine AN patients were reassessed. Before treatment, the AN group showed significantly higher activation than controls in temporal and parietal areas and especially in the temporal superior gyrus during performance of the cognitive task. Control subjects did not show greater activation than AN patients in any region. A negative correlation was found between brain activation and body mass index and a positive correlation between activation and depressive symptomatology. At follow-up after weight recovery, AN patients showed a decrease in brain activation in these areas and did not present differences with respect to controls. These results show that adolescent AN patients showed hyperactivation in the parietal and especially the temporal lobe during a working memory task, suggesting that they must make an additional effort to perform at normal levels. This activation correlated with clinical variables. In these young patients, differences with respect to controls disappeared after weight recovery.
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Reductions of thalamic volume and regional shape changes in the vegetative and the minimally conscious states.
J. Neurotrauma
PUBLISHED: 04-16-2010
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The thalamus is known to play a key role in arousal regulation and support of human consciousness. Neuropathological studies have identified thalamic damage as one of the most common abnormalities present in the brains of patients who were in a vegetative state (VS) or a minimally-conscious state (MCS) state at the time of their deaths. Nonetheless, no in vivo studies of thalamic abnormalities in these patients have been conducted. Using high-resolution T1-weighted magnetic resonance images and a novel approach to shape analysis, we investigated thalamic global and regional changes in a sample of patients in a VS or an MCS. Group comparisons and correlations with clinical variables were performed for the total thalamic volume and for each surface vertex. Total thalamic volume was significantly lower in patients than in healthy volunteers. Shape analysis revealed significant bilateral regional atrophy in the dorso-medial body in patients compared to controls; this atrophy was more widespread in VS than in MCS patients. Lower thalamic volume was significantly correlated with worse Disability Rating Scale scores. Shape analysis suggested that the dorso-medial nucleus and the internal medullar lamina were the main regions responsible for this correlation. Our findings suggest that MCS and VS patients present different patterns of regional thalamic abnormalities, and that these differences partially explain their clinical profile.
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Anterior cingulate and paracingulate sulci morphology in patients with schizophrenia.
Schizophr. Res.
PUBLISHED: 04-11-2010
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The anterior cingulate cortex is a cerebral region engaged in several emotional and cognitive functions. The aim of this study was to investigate possible anterior cingulate and paracingulate sulcal abnormalities in schizophrenia. Twenty-three patients with DSM-IV diagnoses of schizophrenia were compared with 23 healthy subjects matched for age, gender, and parental socioeconomic status. Magnetic resonance images were used to explore the morphology of these regions, with volume and maximum depth being measured by an automated method of sulcal recognition. Additionally, voxel-based morphometry (VBM) was performed to analyze possible reduction in gray and white matter of the anterior cingulate region. A smaller volume of the left anterior cingulate sulcus (ACS) was observed in patients with schizophrenia when compared with healthy controls. Furthermore, female patients showed a reduction in volume of the left ACS and an increase of the right paracingulate sulcus (PCS) compared to female controls. There was also a significant relationship between the depth of right PCS and neuroleptic exposure. VBM analysis showed a reduction in left anterior cingulate gray matter. These findings provide further evidence of left anterior middle frontal cortex abnormalities in schizophrenia. In addition, the results suggest gender differences in the structural abnormalities of the illness.
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Diffusion weighted imaging distinguishes the vegetative state from the minimally conscious state.
Neuroimage
PUBLISHED: 04-02-2010
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The vegetative (VS) and minimally conscious (MCS) states are currently distinguished on the basis of exhibited behaviour rather than underlying pathology. Although previous histopathological studies have documented different degrees of diffuse axonal injury as well as damage to the thalami and brainstem regions in VS and MCS, these differences have not been assessed in vivo, and therefore, do not provide a measurable pathological marker to aid clinical diagnosis. Currently, the diagnostic decision-making process is highly subjective and prone to error. Indeed, previous work has suggested that up to 43% of patients in this group may be misdiagnosed. We used diffusion tensor imaging (DTI) to study the neuropathology of 25 vegetative and minimally conscious patients in vivo and to identify measures that could potentially distinguish the patients in these two groups. Mean diffusivity (MD) maps of the subcortical white matter, brainstem and thalami were generated. The MCS and VS patients differed significantly in subcortical white matter and thalamic regions, but appeared not to differ in the brainstem. Moreover, the DTI results predicted scores on the Coma Recovery Scale (p<0.001) and successfully classified the patients in to their appropriate diagnostic categories with an accuracy of 95%. The results suggest that this method may provide an objective and highly accurate method for classifying these challenging patient populations and may therefore complement the behavioural assessment to inform the diagnostic decision making process.
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White matter microstructure in female to male transsexuals before cross-sex hormonal treatment. A diffusion tensor imaging study.
J Psychiatr Res
PUBLISHED: 03-04-2010
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Some gray and white matter regions of the brain are sexually dimorphic. The best MRI technique for identifying subtle differences in white matter is diffusion tensor imaging (DTI). The purpose of this paper is to investigate whether white matter patterns in female to male (FtM) transsexuals before commencing cross-sex hormone treatment are more similar to that of their biological sex or to that of their gender identity.
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Frontal and associative visual areas related to visual hallucinations in dementia with Lewy bodies and Parkinsons disease with dementia.
Mov. Disord.
PUBLISHED: 02-23-2010
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Visual Hallucinations (VH) are among the core features of Dementia with Lewy Bodies (DLB), but are also very frequent in demented patients with Parkinsons Disease (PDD). The purpose of this study was to investigate the pattern of gray matter and cognitive impairment underlying VH in DLB and PDD. We applied voxel-based morphometry and behavioral assessment to 12 clinically diagnosed DLB patients and 15 PDD patients. Subjects with VH showed greater gray matter loss than non-hallucinators, specifically in the right inferior frontal gyrus (BA 45) in the DLB patients and in the left orbitofrontal lobe (BA 10) in the PDD patients. Comparing the two subgroups with VH, DLB patients had greater decrease of the bilateral premotor area (BA 6) than PDD patients. Furthermore, decreased volume in associative visual areas, namely left precuneus and inferior frontal lobe, correlated with VH in the DLB but not in PDD patients. VH were related to impaired verbal fluency, inhibitory control of attention and visuoperception in the DLB group and to visual memory in the PDD group. In conclusion, DLB and PDD patients with VH had more frontal gray matter atrophy than non-hallucinators, the impairment being greater in the DLB group. The patterns of structural and functional correlations were different in both pathologies.
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Progressive gray matter atrophy in lacunar patients with vascular mild cognitive impairment.
Cerebrovasc. Dis.
PUBLISHED: 02-12-2010
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We investigated the progression of cognitive and cerebral changes in 30 patients with a first-ever lacunar infarct (LI): 15 with vascular mild cognitive impairment (MCI-V) and 15 without cognitive impairment. All cases were followed up 18 +/- 6 months after the stroke and underwent neurological, neuropsychological and MRI assessments at baseline and longitudinally.
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Cortical activation during mental rotation in male-to-female and female-to-male transsexuals under hormonal treatment.
Psychoneuroendocrinology
PUBLISHED: 02-08-2010
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There is strong evidence of sex differences in mental rotation tasks. Transsexualism is an extreme gender identity disorder in which individuals seek cross-gender treatment to change their sex. The aim of our study was to investigate if male-to-female (MF) and female-to-male (FM) transsexuals receiving cross-sex hormonal treatment have different patterns of cortical activation during a three-dimensional (3D) mental rotation task. An fMRI study was performed using a 3-T scan in a sample of 18 MF and 19 FM under chronic cross-sex hormonal treatment. Twenty-three males and 19 females served as controls. The general pattern of cerebral activation seen while visualizing the rotated and non-rotated figures was similar for all four groups showing strong occipito-parieto-frontal brain activation. However, compared to control males, the activation of MF transsexuals during the task was lower in the superior parietal lobe. Compared to control females, MF transsexuals showed higher activation in orbital and right dorsolateral prefrontal regions and lower activation in the left prefrontal gyrus. FM transsexuals did not differ from either the MF transsexual or control groups. Regression analyses between cerebral activation and the number of months of hormonal treatment showed a significant negative correlation in parietal, occipital and temporal regions in the MF transsexuals. No significant correlations with time were seen in the FM transsexuals. In conclusion, although we did not find a specific pattern of cerebral activation in the FM transsexuals, we have identified a specific pattern of cerebral activation during a mental 3D rotation task in MF transsexuals under cross-sex hormonal treatment that differed from control males in the parietal region and from control females in the orbital prefrontal region. The hypoactivation in MF transsexuals in the parietal region could be due to the hormonal treatment or could reflect a priori cerebral differences between MF transsexual and control subjects.
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Multiple DTI index analysis in normal aging, amnestic MCI and AD. Relationship with neuropsychological performance.
Neurobiol. Aging
PUBLISHED: 02-03-2010
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White matter (WM) damage has been reported in Alzheimers Disease (AD) and Mild Cognitive Impairment (MCI) in diffusion tensor imaging (DTI) studies. It is, however, unknown how the investigation of multiple tensor indexes in the same patients, can differentiate them from normal aging or relate to patients cognition. Forty-six individuals (15 healthy, 16 a-MCI and 15 AD) were included. Voxel-based tract based spatial-statistics (TBSS) was used to obtain whole-brain maps of main WM bundles for fractional anisotropy (FA), radial diffusivity (DR), axial diffusivity (DA) and mean diffusivity (MD). FA reductions were evidenced among AD patients with posterior predominance. A-MCI patients displayed reduced mean FA in these critical regions, compared to healthy elders. MD increases were widespread in both groups of patients. Interestingly, a-MCI patients exhibited DR increases in overlapping areas of FA shrinkages in AD, whereas DA increases were only observed in AD. Gray matter atrophy explained most DTI differences, except those regarding MD in both groups as well as DR increases in posterior associative pathways among a-MCI cases. FA values were the only DTI measure significantly related to memory performance among patients. Present findings suggest that most DTI-derived changes in AD and a-MCI are largely secondary to gray matter atrophy. Notably however, specific DR signal increases in posterior parts of the inferior fronto-occipital and longitudinal fasciculi may reflect early WM compromise in preclinical dementia, which is independent of atrophy. Finally, global measures of integrity, particularly orientation coherence (FA) of diffusion, appear to be more closely related to the cognitive profile of our patients than indexes reflecting water movement parallel (DA) and perpendicular (DR) to the primary diffusion direction.
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Differential progression of brain atrophy in Parkinsons disease with and without visual hallucinations.
J. Neurol. Neurosurg. Psychiatr.
PUBLISHED: 12-03-2009
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To determine the course of cognitive deficits and the regional progression of brain atrophy in patients with Parkinsons disease (PD) with and without visual hallucinations (VH).
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Decreased regional brain volume and cognitive impairment in preterm children at low risk.
Pediatrics
PUBLISHED: 12-02-2009
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To investigate whether preterm children with low risk for neurodevelopmental deficits show long-term changes in gray matter (GM) and white matter (WM) volumes compared with term children and to relate these changes to cognitive outcome.
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MRI and cognitive impairment in Parkinsons disease.
Mov. Disord.
PUBLISHED: 10-31-2009
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Patients with Parkinsons disease (PD) may present impairment in cognitive functions even at early stages of the disease. When compared with the general population, their risk of dementia is five to six times higher. Recent investigations using structural MRI have shown that dementia in PD is related to cortical structural changes and that specific cognitive dysfunctions can be attributed to atrophy in specific structures. We review the structural MRI studies carried out in PD using either a manual region of interest (ROI) approach or voxel-based morphometry (VBM). ROI studies have shown that hippocampal volume is decreased in patients with PD with and without dementia; in addition, hippocampal atrophy correlated with deficits in verbal memory. VBM studies have demonstrated that dementia in PD involves structural changes in limbic areas and widespread cortical atrophy. Findings in nondemented patients with PD are less conclusive, possibly because cognitively heterogeneous groups of patients have been studied. Patients with PD with cognitive impairment and/or visual hallucinations present greater brain atrophy than patients without these characteristics. These findings suggest that cortical atrophy is related to cognitive dysfunction in PD and precedes the development of dementia. Structural MRI might therefore provide an early marker for dementia in PD.
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Cerebrospinal tau, phospho-tau, and beta-amyloid and neuropsychological functions in Parkinsons disease.
Mov. Disord.
PUBLISHED: 10-02-2009
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Alzheimers disease (AD)-pathology may play a role in Parkinsons disease (PD)-related dementia (PDD). The aim of this study was to assess cerebrospinal fluid (CSF) levels of tau, phospho-tau, and beta-amyloid, proposed AD biomarkers, and their relationship with cognitive function in PD. Forty PD patients [20 nondemented (PDND); 20 PDD] and 30 controls underwent CSF tau, phospho-tau, and beta-amyloid analysis using specific ELISA techniques. All PD patients and 15 controls underwent neuropsychological testing of fronto-subcortical (attention, fluency) and neocortical (memory, naming, visuoperceptive) functions. CSF markers levels were compared between groups, and compared and correlated with neuropsychological measures in PDND and PDD separately and as a continuum (PD). CSF tau and phospho-tau were higher in PDD than in PDND and controls (P < 0.05). CSF beta-amyloid ranged from high (controls) to intermediate (PDND) and low (PDD) levels (P < 0.001). In all PD and PDD patients, high CSF tau and phospho-tau were associated with impaired memory and naming. In PDND, CSF beta-amyloid was related with phonetic fluency. These findings suggest underlying AD-pathology in PDD in association with cortical cognitive dysfunction, and that low CSF beta-amyloid in PDND patients with impaired phonetic fluency can constitute an early marker of cognitive dysfunction.
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Neuroanatomical correlates of impaired decision-making and facial emotion recognition in early Parkinsons disease.
Eur. J. Neurosci.
PUBLISHED: 09-04-2009
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Decision-making and recognition of emotions are often impaired in patients with Parkinsons disease (PD). The orbitofrontal cortex (OFC) and the amygdala are critical structures subserving these functions. This study was designed to test whether there are any structural changes in these areas that might explain the impairment of decision-making and recognition of facial emotions in early PD. We used the Iowa Gambling Task (IGT) and the Ekman 60 faces test which are sensitive to the integrity of OFC and amygdala dysfunctions in 24 early PD patients and 24 controls. High-resolution structural magnetic resonance images (MRI) were also obtained. Group analysis using voxel-based morphometry (VBM) showed significant and corrected (P < 0.05 FEW-small volume correction) gray matter (GM) loss in the right amygdala and bilaterally in the OFC in PD patients. Volumetric analyses were also performed but did not yield significant differences between groups. Left lateral GM volume in OFC showed a slight correlation with the IGT, and bilateral OFC GM was strongly correlated with Ekman test performance in PD patients. We conclude that: (i) impairment in decision-making and recognition of facial emotions occurs at the early stages of PD, (ii) these neuropsychological deficits are accompanied by degeneration of OFC and amygdala, and (iii) bilateral OFC reductions are associated with impaired recognition of emotions, and GM volume loss in left lateral OFC is related to decision-making impairment in PD.
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Brain structure and function related to cognitive reserve variables in normal aging, mild cognitive impairment and Alzheimers disease.
Neurobiol. Aging
PUBLISHED: 08-22-2009
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Cognitive reserve (CR) is the brains capacity to cope with cerebral damage to minimize clinical manifestations. The passive model considers head or brain measures as anatomical substrates of CR, whereas the active model emphasizes the use of brain networks effectively. Sixteen healthy subjects, 12 amnestic mild cognitive impairment (MCI) and 16 cases with mild Alzheimers disease (AD) were included to investigate the relationships between proxies of CR and cerebral measures considered in the passive and active models. CR proxies were inferred premorbid IQ (WAIS Vocabulary test), education-occupation, a questionnaire of intellectual and social activities and a composite CR measure. MRI-derived whole-brain volumes and brain activity by functional MRI during a visual encoding task were obtained. Among healthy elders, higher CR was related to larger brains and reduced activity during cognitive processing, suggesting more effective use of cerebral networks. In contrast, higher CR was associated with reduced brain volumes in MCI and AD and increased brain function in the latter, indicating more advanced neuropathology but that active compensatory mechanisms are still at work in higher CR patients. The right superior temporal gyrus (BA 22) and the left superior parietal lobe (BA 7) showed greatest significant differences in direction of slope with CR and activation between controls and AD cases. Finally, a regression analysis revealed that fMRI patterns were more closely related to CR proxies than brain volumes. Overall, inverse relationships for healthy and pathological aging groups emerged between brain structure and function and CR variables.
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Correlations between gray matter reductions and cognitive deficits in dementia with Lewy Bodies and Parkinsons disease with dementia.
Mov. Disord.
PUBLISHED: 07-02-2009
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There is controversy regarding whether Dementia with Lewy Bodies (DLB) and Parkinsons disease with dementia (PDD) may or not be different manifestations of the same disorder. The purpose of the present study was to investigate possible correlations between brain structure and neuropsychological functions in clinically diagnosed patients with DLB and PDD. The study sample consisted of 12 consecutively referred DLB patients, 16 PDD patients, and 16 healthy control subjects recruited from an outpatient setting, who underwent MRI and neuropsychological assessment. Voxel-based morphometry results showed that DLB patients had greater gray matter atrophy in the right superior frontal gyrus, the right premotor area and the right inferior frontal lobe compared to PDD. Furthermore, the anterior cingulate and prefrontal volume correlated with performance on the Continuous Performance Test while the right hippocampus and amygdala volume correlated with Visual Memory Test in the DLB group. In conclusion, DLB patients had more fronto-temporal gray matter atrophy than PDD patients and these reductions correlated with neuropsychological impairment.
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Interactions of cognitive reserve with regional brain anatomy and brain function during a working memory task in healthy elders.
Biol Psychol
PUBLISHED: 05-09-2009
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Cognitive reserve (CR) defines the capacity of the adult brain to cope with pathology in order to minimize symptomatology. Relevant lifetime social, cognitive and leisure activities represent measurable proxies of cognitive CR but its underlying structural and functional brain mechanisms remain poorly understood. We investigated the relationship between CR and regional gray matter volumes and brain activity (fMRI) during a working memory task in a sample of healthy elders. Participants with higher CR had larger gray matter volumes in frontal and parietal regions. Conversely, a negative correlation was observed between CR and fMRI signal in the right inferior frontal cortex, suggesting increased neural efficiency for higher CR individuals. This latter association however disappeared after adjusting for gray matter images in a voxel-based manner. Altogether, present results may reflect both general and specific anatomofunctional correlates of CR in the healthy elders. Thus, whereas heteromodal anterior and posterior gray matter regions correspond to passive (i.e. morphological) correlates of CR unrelated to functional brain activation during this particular cognitive task, the right inferior frontal area reveals interactions between active and passive components of CR related to the cognitive functions tested in the fMRI study.
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Neuroanatomical substrate of visuospatial and visuoperceptual impairment in Parkinsons disease.
Mov. Disord.
PUBLISHED: 05-05-2009
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To determine magnetic resonance imaging patterns of gray matter (GM) atrophy underlying visuospatial and visuoperceptual impairment in Parkinsons disease (PD), we applied voxel-based morphometry to 36 nondemented PD patients and correlated their whole brain GM density with performance on three visuospatial and visuoperceptual tests. In addition, group comparisons between patients and 20 healthy controls were also performed. Correlations between visuospatial performance and GM density were found in the superior parietal lobules and the superior occipital gyrus of PD patients. Poor performance on visuoperceptual tests was also found to be significantly associated with GM decreases in the fusiform, the parahippocampus, and the middle occipital gyrus. Finally, group comparisons between controls and patients showed widespread GM cortical reductions in PD, involving posterior temporal and parietal regions. Taken together, these findings suggest that visuospatial and visuoperceptual dysfunctions reflect structural GM changes in temporo-parietal cortical regions of PD patients.
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Magnetic resonance imaging study of cerebral sulci in low-risk preterm children.
Int. J. Dev. Neurosci.
PUBLISHED: 05-04-2009
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Premature birth is associated with several brain dysfunctions including changes in the normal pattern of sulcal development. Previous studies on sulcal abnormalities were performed in subjects with perinatal brain complications. We selected a sample of preterm subjects with a low risk of neurodevelopmental abnormalities with the aim of investigating the effects of prematurity per se. Surface and maximum depth measures of four sulci that develop at different gestational ages were obtained using Anatomist/Brain Visa 3.0.2 software. The sulci measured were the olfactory sulcus (16 weeks), the parieto-occipital sulcus (22-23 weeks), the superior temporal sulcus (32 weeks) and the orbitofrontal sulcus (36-39 weeks). The sample comprised 17 low-risk preterms (mean gestational age: 32 weeks) and 16 full-term children who were matched for age at scan, gender, handedness and socio-cultural status. Analysis of surface variance showed a significant group effect (P<0.015), as well as an interaction between the type of sulcus and group (P<0.001). The superior temporal sulcus surface was inferior in the low-risk preterm group compared to controls. Our findings suggest that even without perinatal complications, premature birth affects sulcal morphology.
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Mental slowness and executive dysfunctions in patients with metabolic syndrome.
Neurosci. Lett.
PUBLISHED: 04-23-2009
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Metabolic Syndrome is a cluster of vascular risk factors which has been related to dementia and cognitive decline. The aim of this study was to describe the neuropsychological profile of metabolic syndrome patients. An extensive neuropsychological protocol was administered to 55 patients and 35 controls assessing memory, executive, visuoperceptual and visuoconstructive functions, language and speed of processing. There were differences between groups in speed of processing and some executive functions after controlling for the influences of education and gender. The results suggest that metabolic syndrome may be a prodromal state of vascular cognitive impairment.
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Cognitive reserve modulates task-induced activations and deactivations in healthy elders, amnestic mild cognitive impairment and mild Alzheimers disease.
Cortex
PUBLISHED: 04-20-2009
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Cognitive reserve (CR) reflects the capacity of the brain to endure neuropathology in order to minimize clinical manifestations. Previous studies showed that CR modulates the patterns of brain activity in both healthy and clinical populations. In the present study we sought to determine whether reorganizations of functional brain resources linked to CR could already be observed in amnestic mild cognitive impairment (a-MCI) and mild Alzheimers disease (AD) patients when performing a task corresponding to an unaffected cognitive domain. We further investigated if activity in regions showing task-induced deactivations, usually identified as pertaining to the default-mode network (DMN), was also influenced by CR.
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Olfactory dysfunction after subarachnoid hemorrhage caused by ruptured aneurysms of the anterior communicating artery. Clinical article.
J. Neurosurg.
PUBLISHED: 04-14-2009
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Olfactory dysfunction has an important impact on quality of life. In patients with subarachnoid hemorrhage (SAH), anosmia has mainly been reported after surgery for aneurysms of the anterior communicating artery (ACoA). The authors studied whether and how frequently patients with ACoA aneurysms present with smell identification deficits in 2 treatment groups (endovascular and surgical treatment).
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Structural brain correlates of verbal fluency in Parkinsons disease.
Neuroreport
PUBLISHED: 04-08-2009
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Verbal fluency tests are often used to assess cognitive dysfunction in Parkinsons disease. These tests have been found to be impaired even in initial stages of this illness. We applied voxel-based morphometry to investigate the neuroanatomic substrates of semantic and phonemic fluency impairment. Correlations between gray matter density and semantic as well as phonemic fluency performance were performed in 32 nondemented Parkinsons disease patients. We found that gray matter of temporal, frontal and cerebellar areas correlated with semantic fluency scores. In contrast, no gray matter correlations were found for phonemic fluency or for general cognitive functions. These results suggest that semantic fluency impairment is reflecting structural gray matter changes in regions involved in language networks.
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Neuropsychologic impairment in bilateral cerebral palsy.
Pediatr. Neurol.
PUBLISHED: 04-02-2009
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The lower-than-average cognitive performance of individuals with bilateral cerebral palsy found in previous studies does not always refer to an abnormal performance or clinically significant impairment. We aimed to establish the percentage of persons with bilateral cerebral palsy who present neuropsychologic impairment, and its relationship to perinatal data and motor signs. Forty children, adolescents, and adults (age range, 6-38 years; 15 females and 25 males) with bilateral cerebral palsy were neuropsychologically assessed. Vocabulary was impaired in 85% of participants, language comprehension in 13-48%, visuoperceptual abilities in 60%, visuospatial abilities in 90%, short-term memory in 21-58%, declarative memory in 47-67%, and praxis comprehension in 20%, with executive deficits in 58-74%. Perinatal data (intrauterine growth and birth weight) contributed to explaining memory impairment. Among cerebral palsy subtypes (spastic, mixed, and dyskinetic), forms of impairment differed only in short-term verbal memory. No persons with dyskinetic cerebral palsy experienced impairment in immediate memory or working visual memory. We conclude that visuospatial deficit is the most frequent impairment in people with bilateral cerebral palsy. Moreover, short-term memory impairment seems sensitive to perinatal complications, and differs among bilateral cerebral palsy subtypes.
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Brain changes in children and adolescents with obsessive-compulsive disorder before and after treatment: a voxel-based morphometric MRI study.
Psychiatry Res
PUBLISHED: 03-24-2009
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The aim of this study is to determine whether children and adolescents with treatment-naïve obsessive-compulsive disorder (OCD) present brain structure differences in comparison with healthy subjects, and to evaluate brain changes after treatment and clinical improvement. Initial and 6 months follow-up evaluations were performed in 15 children and adolescents (age range=9-17 years, mean=13.7, S.D.=2.5; 8 male, 7 female) with DSM-IV OCD and 15 healthy subjects matched for age, sex and estimated intellectual level. An evaluation with psychopathological scales and magnetic resonance imaging (MRI) was carried out at admission and after 6 months follow-up. Axial three-dimensional T1-weighted images were obtained in a 1.5 T scanner and analysed using optimized voxel-based morphometry (VBM) and longitudinal VBM approaches. Compared with controls, OCD patients presented significantly less gray matter volume bilaterally in right and left parietal lobes and right parietal white matter (P=0.001 FWE corrected) at baseline evaluation. After 6 months of treatment, and with a clear clinical improvement, the differences between OCD patients and controls in the parietal lobes in gray and white matter were no longer statistically significant. During follow-up in the longitudinal study, an increase in gray matter volume in the right striatum of OCD patients was observed, though the difference was not statistically significant. Children and adolescents with untreated OCD present gray and white matter decreases in lateral parietal cortices, but this abnormality is reversible after clinical improvement.
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A cross-sectional and follow-up voxel-based morphometric MRI study in adolescent anorexia nervosa.
J Psychiatr Res
PUBLISHED: 03-20-2009
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The objective was to examine whether cerebral volumes are reduced, and in what regions, in adolescents with anorexia nervosa and to study changes after nutritional recovery. Twelve anorexia nervosa (DSM-IV) patients aged 11-17 consecutively admitted to an Eating Disorders Unit were assessed by means of psychopathological scales, neuropsychological battery and voxel-based morphometric (VBM) magnetic resonance imaging at admission and after 7 months follow-up. Nine control subjects of similar age, gender and estimated intelligence level were also studied. The two groups showed differences in gray matter (F=22.2; p<0.001) and cerebrospinal fluid (CSF) (F=21.2; p<0.001) but not in white matter volumes. In anorexic patients, gray matter volume correlated negatively with the copy time from the Rey Complex Figure Test. In the regional VBM study several temporal and parietal gray matter regions were reduced. During follow-up there was a greater global increase in gray matter (F=10.7; p=0.004) and decrease in CSF (F=22.1; p=0.001) in anorexic patients. The increase in gray matter correlated with a decrease in cortisol (Spearman correlation=-0.73; p=0.017). At follow-up there were no differences in global gray matter (F=2.1; p=0.165), white matter (F=0.02, p=0.965) or CSF (F=1.8; p=0.113) volumes between both groups. There were still some smaller areas, in the right temporal and both supplementary motor area, showing differences between them in the regional VBM study. In conclusion, in adolescent anorexic patients gray matter is more affected than white matter and mainly involves the posterior regions of the brain. Overall gray matter alterations are reversible after nutritional recovery.
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Quality of life and neurobehavioral changes in survivors of malignant middle cerebral artery infarction.
J. Neurol.
PUBLISHED: 02-18-2009
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Malignant middle cerebral artery (MMCA) infarction is associated with a mortality rate of 80% under conservative treatment. Decompressive hemicraniectomy (DH) reduces mortality and improves the functional outcome of surviving patients. The purpose of this study was to examine quality of life (QoL) and neurobehavioral deficits in patients with space-occupying infarctions of the right- or left-sided hemisphere at 6 months after stroke. The Sickness Impact Profile (SIP) was used to assess QoL in 19 out of 29 consecutive patients that underwent DH after a malignant MCA infarction (14 on the right and 5 on the left hemisphere). Behavioral changes were evaluated with the Frontal Behavioral Inventory and the Beck Depression Inventory. Patients and relatives were also asked if, knowing the present outcome, they would agree again, in retrospect, to a DH. Barthel Index >60 was seen in 37% of our patients. Functional outcome was related to age. We found a higher reduction in the SIPs physical domain than in the psychosocial domain. Depressive symptoms were present in 50% of the patients. We didnt find significant differences in QoL or functional outcome between patients with right or left-sided infarctions. The most frequent neurobehavioral symptoms were decreased speech output, apathy, reduced spontaneity and irritability. Most patients and their relatives would again give consent to hemicraniectomy. The results show that younger patients had a significantly better outcome. QoL seems to be acceptable in both left- and right-sided infarctions, and retrospective agreement to hemicraniectomy is high in both patients and their relatives.
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Hippocampal underactivation in an fMRI study of word and face memory recognition in schizophrenia.
Eur Arch Psychiatry Clin Neurosci
PUBLISHED: 02-17-2009
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Schizophrenia is a major mental disorder which is characterized by several cognitive deficits. Investigations of the neural basis of memory dysfunctions using neuroimaging techniques suggest that the hippocampus plays an important role in declarative memory impairment. The goal of this study was to investigate possible dysfunctions in cerebral activation in schizophrenic patients during both word and face recognition memory tasks. We tested 22 schizophrenics and 24 controls matched by gender, age, handedness and parental socioeconomic status. Compared to healthy volunteers, patients with schizophrenia showed decreased bilateral hippocampal activation during word and face recognition tasks. The whole brain analysis also showed a pattern of cortical and subcortical hypoactivation for both verbal and non-verbal recognition. This study provides further evidence of hippocampal involvement in declarative memory impairments of schizophrenia.
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A voxel-based diffusion tensor imaging study of temporal white matter in patients with schizophrenia.
Psychiatry Res
PUBLISHED: 02-13-2009
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Diffusion tensor imaging (DTI) is a relatively new technique used to detect changes in the anisotropic diffusion of white matter. The study of the disruption of brain connectivity may increase our understanding of cognitive deficits associated with schizophrenia. Here we analysed DTI data in 25 patients with DSM-IV schizophrenia and 24 healthy controls. Two complementary measures, fractional anisotropy (FA) and the apparent diffusion coefficient (ADC), were considered and analysed using voxel-based morphometry. Declarative memory functions were also investigated and their associations with DTI data were analysed. FA was significantly reduced, and the ADC increased in the left sub-gyral white matter of the temporal lobe, which involves the posterior part of the fornix. In the schizophrenic group, females had lower FA than males in the genu of the corpus callosum. Memory functions correlate with FA values. These data provide further evidence for the disruption of white matter connectivity in the left medial temporal lobe, and for its contribution to the declarative memory deficit in schizophrenia.
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APOE status modulates the changes in network connectivity induced by brain stimulation in non-demented elders.
PLoS ONE
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Behavioral consequences of a brain insult represent an interaction between the injury and the capacity of the rest of the brain to adapt to it. We provide experimental support for the notion that genetic factors play a critical role in such adaptation. We induced a controlled brain disruption using repetitive transcranial magnetic stimulation (rTMS) and show that APOE status determines its impact on distributed brain networks as assessed by functional MRI (fMRI).Twenty non-demented elders exhibiting mild memory dysfunction underwent two fMRI studies during face-name encoding tasks (before and after rTMS). Baseline task performance was associated with activation of a network of brain regions in prefrontal, parietal, medial temporal and visual associative areas. APOE ?4 bearers exhibited this pattern in two separate independent components, whereas ?4-non carriers presented a single partially overlapping network. Following rTMS all subjects showed slight ameliorations in memory performance, regardless of APOE status. However, after rTMS APOE ?4-carriers showed significant changes in brain network activation, expressing strikingly similar spatial configuration as the one observed in the non-carrier group prior to stimulation. Similarly, activity in areas of the default-mode network (DMN) was found in a single component among the ?4-non bearers, whereas among carriers it appeared disaggregated in three distinct spatiotemporal components that changed to an integrated single component after rTMS.Our findings demonstrate that genetic background play a fundamental role in the brain responses to focal insults, conditioning expression of distinct brain networks to sustain similar cognitive performance.
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Progression of cortical thinning in early Parkinsons disease.
Mov. Disord.
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The aim of this study was to investigate the progression of cortical thinning and gray-matter (GM) volume loss in early Parkinsons disease (PD). MRI and neuropsychological assessment were obtained at baseline and follow-up (mean ± standard deviation = 35.50 ± 1.88 months) in a group of 16 early-PD patients (H & Y stage ?II and disease duration ?5 years) and 15 healthy controls matched for age, gender, and years of education. FreeSurfer software was used for the analysis of cortical thickness as well as for cortical and subcortical volumetric analyses. Voxel-based morphometry analysis was performed using SPM8. Compared to controls, PD patients showed greater regional cortical thinning in bilateral frontotemporal regions as well as greater over-time total GM loss and amygdalar volume reduction. PD patients and controls presented similar over-time changes in cognitive functioning. In early-PD patients, global GM loss, amygdalar atrophy, and cortical thinning in frontotemporal regions are specifically associated with the PD-degenerative process.
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Progressive changes in a recognition memory network in Parkinsons disease.
J. Neurol. Neurosurg. Psychiatr.
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In a previous functional MRI (fMRI) study, we found that patients with Parkinsons disease (PD) presented with dysfunctions in the recruitment of recognition memory networks. We aimed to investigate the changes in these networks over time.
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A role for the default mode network in the bases of disorders of consciousness.
Ann. Neurol.
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Functional connectivity in the default mode network (DMN) is known to be reduced in patients with disorders of consciousness, to a different extent depending on their clinical severity. Nevertheless, the integrity of the structural architecture supporting this network and its relation with the exhibited functional disconnections are very poorly understood. We investigated the structural connectivity and white matter integrity of the DMN in patients with disorders of consciousness of varying clinical severity.
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Cortical thickness in untreated transsexuals.
Cereb. Cortex
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Sex differences in cortical thickness (CTh) have been extensively investigated but as yet there are no reports on CTh in transsexuals. Our aim was to determine whether the CTh pattern in transsexuals before hormonal treatment follows their biological sex or their gender identity. We performed brain magnetic resonance imaging on 94 subjects: 24 untreated female-to-male transsexuals (FtMs), 18 untreated male-to-female transsexuals (MtFs), and 29 male and 23 female controls in a 3-T TIM-TRIO Siemens scanner. T1-weighted images were analyzed to obtain CTh and volumetric subcortical measurements with FreeSurfer software. CTh maps showed control females have thicker cortex than control males in the frontal and parietal regions. In contrast, males have greater right putamen volume. FtMs had a similar CTh to control females and greater CTh than males in the parietal and temporal cortices. FtMs had larger right putamen than females but did not differ from males. MtFs did not differ in CTh from female controls but had greater CTh than control males in the orbitofrontal, insular, and medial occipital regions. In conclusion, FtMs showed evidence of subcortical gray matter masculinization, while MtFs showed evidence of CTh feminization. In both types of transsexuals, the differences with respect to their biological sex are located in the right hemisphere.
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