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Find video protocols related to scientific articles indexed in Pubmed.
Proton Magnetic Resonance Spectroscopy Assessment of Fetal Brain Metabolism in Late-Onset 'Small for Gestational Age' versus 'Intrauterine Growth Restriction' Fetuses.
Fetal. Diagn. Ther.
PUBLISHED: 08-09-2014
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Objectives: We used magnetic resonance spectroscopy (MRS) to evaluate brain metabolic differences in small fetuses near term as compared to appropriate for gestational age (AGA) fetuses. Study Design: 71 term small fetuses (estimated fetal weight <10th centile for gestational age with normal umbilical artery Doppler sonography) were subclassified as late intrauterine growth restriction (IUGR) (n = 50) or small for gestational age (SGA) (n = 21), and compared with 65 AGA fetuses. IUGR was defined by either abnormal middle cerebral artery, abnormal uterine artery Doppler sonography or estimated fetal weight <3rd centile. All participants underwent brain magnetic resonance imaging at 37 weeks of gestation, and single-voxel magnetic resonance spectra were obtained from the frontal lobe on a 3-tesla scanner. N-acetylaspartate (NAA)/choline (Cho), NAA/creatine (Cr) and Cho/Cr ratios were calculated and compared between cases and controls. The association of the metabolic ratios with the study groups was tested. Results: After MRS processing and applying quality control criteria, 31 spectra from late-onset IUGR, 11 from SGA and 30 from AGA fetuses were selected for further analysis. Both SGA and late-onset IUGR fetuses showed significantly reduced NAA/Cho levels when compared to AGA fetuses. This decrease followed a linear trend across the three clinical groups that were considered. Conclusions: Both SGA and late-onset IUGR fetuses showed differences in MRS brain metabolic ratios. The findings suggest that despite near-normal perinatal outcomes, SGA fetuses are not constitutionally small and may represent a form of growth disorder that needs to be clarified. © 2014 S. Karger AG, Basel.
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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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Remote thalamic microstructural abnormalities related to cognitive function in ischemic stroke patients.
Neuropsychology
PUBLISHED: 06-02-2014
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Ischemic stroke can lead to a continuum of cognitive sequelae, ranging from mild vascular cognitive impairment to vascular dementia. These cognitive deficits can be influenced by the disruption of cortico-subcortical circuits. We sought to explore remote thalamic microstructural abnormalities and their association with cognitive function after ischemic stroke.
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Clinical Role of Subtraction Ictal SPECT Coregistered to MR Imaging and 18F-FDG PET in Pediatric Epilepsy.
J. Nucl. Med.
PUBLISHED: 05-05-2014
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A precise assessment of the drug-resistant epileptic pediatric population for surgical candidacy is often challenging, and to date there are no evidence-based guidelines for presurgical identification of the epileptogenic zone. To evaluate the usefulness of radionuclide imaging techniques for presurgical evaluation of epileptic pediatric patients, we compared the results of video-electroencephalography (EEG), brain MR imaging, interictal SPECT, ictal SPECT, subtraction ictal SPECT coregistered to MR imaging (SISCOM), and interictal PET with (18)F-FDG.
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Impairment of functional integration of the default mode network correlates with cognitive outcome at three months after stroke.
Hum Brain Mapp
PUBLISHED: 04-26-2014
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Resting-state studies conducted with stroke patients are scarce. The study of brain activity and connectivity at rest provides a unique opportunity for the investigation of brain rewiring after stroke and plasticity changes. This study sought to identify dynamic changes in the functional organization of the default mode network (DMN) of stroke patients at three months after stroke. Eleven patients (eight male and three female; age range: 48-72) with right cortical and subcortical ischemic infarctions and 17 controls (eleven males and six females; age range: 57-69) were assessed by neurological and neuropsychological examinations and scanned with resting-state functional magnetic ressonance imaging. First, we explored group differences in functional activity within the DMN by means of probabilistic independent component analysis followed by a dual regression approach. Second, we estimated functional connectivity between 11 DMN nodes both locally by means of seed-based connectivity analysis, as well as globally by means of graph-computation analysis. We found that patients had greater DMN activity in the left precuneus and the left anterior cingulate gyrus when compared with healthy controls (P?
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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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Multisite longitudinal reliability of tract-based spatial statistics in diffusion tensor imaging of healthy elderly subjects.
Neuroimage
PUBLISHED: 02-19-2014
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Large-scale longitudinal neuroimaging studies with diffusion imaging techniques are necessary to test and validate models of white matter neurophysiological processes that change in time, both in healthy and diseased brains. The predictive power of such longitudinal models will always be limited by the reproducibility of repeated measures acquired during different sessions. At present, there is limited quantitative knowledge about the across-session reproducibility of standard diffusion metrics in 3T multi-centric studies on subjects in stable conditions, in particular when using tract based spatial statistics and with elderly people. In this study we implemented a multi-site brain diffusion protocol in 10 clinical 3T MRI sites distributed across 4 countries in Europe (Italy, Germany, France and Greece) using vendor provided sequences from Siemens (Allegra, Trio Tim, Verio, Skyra, Biograph mMR), Philips (Achieva) and GE (HDxt) scanners. We acquired DTI data (2 × 2 × 2 mm(3), b = 700 s/mm(2), 5 b0 and 30 diffusion weighted volumes) of a group of healthy stable elderly subjects (5 subjects per site) in two separate sessions at least a week apart. For each subject and session four scalar diffusion metrics were considered: fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial (AD) diffusivity. The diffusion metrics from multiple subjects and sessions at each site were aligned to their common white matter skeleton using tract-based spatial statistics. The reproducibility at each MRI site was examined by looking at group averages of absolute changes relative to the mean (%) on various parameters: i) reproducibility of the signal-to-noise ratio (SNR) of the b0 images in centrum semiovale, ii) full brain test-retest differences of the diffusion metric maps on the white matter skeleton, iii) reproducibility of the diffusion metrics on atlas-based white matter ROIs on the white matter skeleton. Despite the differences of MRI scanner configurations across sites (vendors, models, RF coils and acquisition sequences) we found good and consistent test-retest reproducibility. White matter b0 SNR reproducibility was on average 7 ± 1% with no significant MRI site effects. Whole brain analysis resulted in no significant test-retest differences at any of the sites with any of the DTI metrics. The atlas-based ROI analysis showed that the mean reproducibility errors largely remained in the 2-4% range for FA and AD and 2-6% for MD and RD, averaged across ROIs. Our results show reproducibility values comparable to those reported in studies using a smaller number of MRI scanners, slightly different DTI protocols and mostly younger populations. We therefore show that the acquisition and analysis protocols used are appropriate for multi-site experimental scenarios.
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Diffusion tensor imaging, intracranial vascular resistance and cognition in middle-aged asymptomatic subjects.
Cerebrovasc. Dis.
PUBLISHED: 02-04-2014
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The contribution of traditional vascular risk factors to cognitive impairment and dementia is well known. However, in order to obtain possible targets for prevention of vascular cognitive impairment (VCI), it may be important to identify other early and noninvasive markers in asymptomatic middle-aged adults. The calculation of middle cerebral artery-pulsatility index (MCA-PI) is an ultrasonologic, noninvasive, validated and easily reproducible technique to assess increased distal resistance to blood flow. This study aims to assess the relationship between MCA-PI, microstructural white matter (WM) integrity and cognition in a middle-aged asymptomatic population.
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Tract-specific fractional anisotropy predicts cognitive outcome in a community sample of middle-aged participants with white matter lesions.
J. Cereb. Blood Flow Metab.
PUBLISHED: 01-14-2014
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Cerebral white matter lesions (WMLs) have been consistently related to cognitive dysfunction but the role of white matter (WM) damage in cognitive impairment is not fully determined. Diffusion tensor imaging is a promising tool to explain impaired cognition related to WMLs. We investigated the separate association of high-grade periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs) with fractional anisotropy (FA) in middle-aged individuals. We also assessed the predictive value to cognition of FA within specific WM tracts associated with high-grade WMLs. One hundred participants from the Barcelona-AsIA Neuropsychology Study were divided into groups based on low- and high-grade WMLs. Voxel-by-voxel FA were compared between groups, with separate analyses for high-grade PVHs and DWMHs. The mean FA within areas showing differences between groups was extracted in each tract for linear regression analyses. Participants with high-grade PVHs and participants with high-grade DWMHs showed lower FA in different areas of specific tracts. Areas showing decreased FA in high-grade DWMHs predicted lower cognition, whereas areas with decreased FA in high-grade PVHs did not. The predictive value to cognition of specific WM tracts supports the involvement of cortico-subcortical circuits in cognitive deficits only in DWMHs.
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Cortical morphology of adolescents with bipolar disorder and with schizophrenia.
Schizophr. Res.
PUBLISHED: 01-08-2014
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Recent evidence points to overlapping decreases in cortical thickness and gyrification in the frontal lobe of patients with adult-onset schizophrenia and bipolar disorder with psychotic symptoms, but it is not clear if these findings generalize to patients with a disease onset during adolescence and what may be the mechanisms underlying a decrease in gyrification.
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Task-dependent activity and connectivity predict episodic memory network-based responses to brain stimulation in healthy aging.
Brain Stimul
PUBLISHED: 01-04-2014
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Transcranial magnetic stimulation (TMS) can affect episodic memory, one of the main cognitive hallmarks of aging, but the mechanisms of action remain unclear.
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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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Structural integrity of the contralesional hemisphere predicts cognitive impairment in ischemic stroke at three months.
PLoS ONE
PUBLISHED: 01-01-2014
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After stroke, white matter integrity can be affected both locally and distally to the primary lesion location. It has been shown that tract disruption in mirror's regions of the contralateral hemisphere is associated with degree of functional impairment. Fourteen patients suffering right hemispheric focal stroke (S) and eighteen healthy controls (HC) underwent Diffusion Weighted Imaging (DWI) and neuropsychological assessment. The stroke patient group was divided into poor (SP; n = 8) and good (SG; n = 6) cognitive recovery groups according to their cognitive improvement from the acute phase (72 hours after stroke) to the subacute phase (3 months post-stroke). Whole-brain DWI data analysis was performed by computing Diffusion Tensor Imaging (DTI) followed by Tract Based Spatial Statistics (TBSS). Assessment of effects was obtained computing the correlation of the projections on TBSS skeleton of Fractional Anisotropy (FA) and Radial Diffusivity (RD) with cognitive test results. Significant decrease of FA was found only in right brain anatomical areas for the S group when compared to the HC group. Analyzed separately, stroke patients with poor cognitive recovery showed additional significant FA decrease in several left hemisphere regions; whereas SG patients showed significant decrease only in the left genu of corpus callosum when compared to the HC. For the SG group, whole brain analysis revealed significant correlation between the performance in the Semantic Fluency test and the FA in the right hemisphere as well as between the performance in the Grooved Pegboard Test (GPT) and the Trail Making Test-part A and the FA in the left hemisphere. For the SP group, correlation analysis revealed significant correlation between the performance in the GPT and the FA in the right hemisphere.
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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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The human cerebral cortex flattens during adolescence.
J. Neurosci.
PUBLISHED: 09-20-2013
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The human cerebral cortex appears to shrink during adolescence. To delineate the dynamic morphological changes involved in this process, 52 healthy male and female adolescents (11-17 years old) were neuroimaged twice using magnetic resonance imaging, approximately 2 years apart. Using a novel morphometric analysis procedure combining the FreeSurfer and BrainVisa image software suites, we quantified global and lobar change in cortical thickness, outer surface area, the gyrification index, the average Euclidean distance between opposing sides of the white matter surface (gyral white matter thickness), the convex ("exposed") part of the outer cortical surface (hull surface area), sulcal length, depth, and width. We found that the cortical surface flattens during adolescence. Flattening was strongest in the frontal and occipital cortices, in which significant sulcal widening and decreased sulcal depth co-occurred. Globally, sulcal widening was associated with cortical thinning and, for the frontal cortex, with loss of surface area. For the other cortical lobes, thinning was related to gyral white matter expansion. The overall flattening of the macrostructural three-dimensional architecture of the human cortex during adolescence thus involves changes in gray matter and effects of the maturation of white matter.
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Cognitive functions in multiple sclerosis: impact of gray matter integrity.
Mult. Scler.
PUBLISHED: 09-04-2013
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Our aim was to investigate the impact of gray matter (GM) integrity on cognitive performance in multiple sclerosis (MS), and its relationship with white matter (WM) integrity and presence of lesions.
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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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Neuropsychiatric systemic lupus erythematosus: magnetic resonance imaging findings and correlation with clinical and immunological features.
Autoimmun Rev
PUBLISHED: 07-01-2013
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Neuropsychiatric (NP) syndromes are a major cause of morbidity and mortality in patients with systemic lupus erythematosus (SLE). The aims of this work were to describe the brain abnormalities in a group of SLE patients during their first episode of NP manifestations using a conventional magnetic resonance imaging (MRI) technique and to investigate the possible correlation between these findings and the clinical and immunological characteristics of these patients. We performed an observational retrospective cross-sectional study that included all patients with NP symptoms who underwent MRI at the Hospital Clinic of Barcelona between the years 2003 and 2012 because of suspecting NP syndromes due to SLE (NPSLE). We studied 43 patients in which 11 types of NPSLE were present, being headache the most frequent, followed by cerebrovascular disease, epileptic crises and cranial neuropathy. A statistically significant association was found between myelopathy and low complement (C4) levels (p=0.035) and disease activity measured as SLE Disease Activity Index (SLEDAI) >4 (p=0.00006). Eighteen (41.9%) patients presented MRI abnormalities. We found an association between myelopathy and the presence of inflammatory or mixed (vascular and inflammatory) type lesions (p=0.003). This pattern was also associated with a high SLEDAI score (p=0.002) and low complement (CH50) levels (p=0.032). We found no relationship between MRI changes and age, time of evolution, or the presence of antiphospholipid or anti-dsDNA antibodies. These results suggest that MRI, although it is the imaging modality of choice in the present moment, by itself does not establish or exclude the diagnosis of NPSLE. In addition, the presence of certain disease activity features (SLEDAI and low complement levels) seems to be associated with the presence of an inflammatory pattern on MRI.
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Ictal EEG-fMRI in localization of epileptogenic area in patients with refractory neocortical focal epilepsy.
Epilepsia
PUBLISHED: 06-24-2013
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To evaluate the usefulness of ictal electroencephalography (EEG)-combined functional magnetic resonance imaging ( MRI) (EEG-fMRI) in localizing epileptogenic zone in refractory neocortical focal epilepsy.
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Normal gray and white matter volume after weight restoration in adolescents with anorexia nervosa.
Int J Eat Disord
PUBLISHED: 06-07-2013
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The aim of this study was to determine whether treated, weight-stabilized adolescents with anorexia nervosa (AN) present brain volume differences in comparison with healthy controls.
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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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Thalamic diffusion differences related to cognitive function in white matter lesions.
Neurobiol. Aging
PUBLISHED: 04-23-2013
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Cerebral white matter lesions (WMLs) are related to cognitive deficits, probably due to a disruption of frontal-subcortical circuits. We explored thalamic diffusion differences related to white matter lesions (WMLs) and their association with cognitive function in middle-aged individuals. Ninety-six participants from the Barcelona-AsIA Neuropsychology Study were included. Participants were classified into groups based on low grade and high grade of periventricular hyperintensities (PVHs) and deep white matter hyperintensities (DWMHs). Tract-Based Spatial Statistics was used to study thalamic diffusion differences between groups. Mean fractional anisotropy (FA) values in significant areas were calculated for each subject and correlated with cognitive performance. Participants with high-grade PVHs and DWMHs showed lower FA thalamic values compared to those with low-grade PVHs and DWMHs, respectively. Decreased FA thalamic values in high-grade DWMHs, but not high-grade PVH, were related to lower levels of performance in psychomotor speed, verbal fluency, and visuospatial skills. Thalamic diffusion differences are related to lower cognitive function only in participants with high-grade DWMHs. These results support the hypothesis that fronto-subcortical disruption is associated with cognitive function only in DWMHs.
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Brain morphometry reproducibility in multi-center 3T MRI studies: a comparison of cross-sectional and longitudinal segmentations.
Neuroimage
PUBLISHED: 03-25-2013
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Large-scale longitudinal multi-site MRI brain morphometry studies are becoming increasingly crucial to characterize both normal and clinical population groups using fully automated segmentation tools. The test-retest reproducibility of morphometry data acquired across multiple scanning sessions, and for different MR vendors, is an important reliability indicator since it defines the sensitivity of a protocol to detect longitudinal effects in a consortium. There is very limited knowledge about how across-session reliability of morphometry estimates might be affected by different 3T MRI systems. Moreover, there is a need for optimal acquisition and analysis protocols in order to reduce sample sizes. A recent study has shown that the longitudinal FreeSurfer segmentation offers improved within session test-retest reproducibility relative to the cross-sectional segmentation at one 3T site using a nonstandard multi-echo MPRAGE sequence. In this study we implement a multi-site 3T MRI morphometry protocol based on vendor provided T1 structural sequences from different vendors (3D MPRAGE on Siemens and Philips, 3D IR-SPGR on GE) implemented in 8 sites located in 4 European countries. The protocols used mild acceleration factors (1.5-2) when possible. We acquired across-session test-retest structural data of a group of healthy elderly subjects (5 subjects per site) and compared the across-session reproducibility of two full-brain automated segmentation methods based on either longitudinal or cross-sectional FreeSurfer processing. The segmentations include cortical thickness, intracranial, ventricle and subcortical volumes. Reproducibility is evaluated as absolute changes relative to the mean (%), Dice coefficient for volume overlap and intraclass correlation coefficients across two sessions. We found that this acquisition and analysis protocol gives comparable reproducibility results to previous studies that used longer acquisitions without acceleration. We also show that the longitudinal processing is systematically more reliable across sites regardless of MRI system differences. The reproducibility errors of the longitudinal segmentations are on average approximately half of those obtained with the cross sectional analysis for all volume segmentations and for entorhinal cortical thickness. No significant differences in reliability are found between the segmentation methods for the other cortical thickness estimates. The average of two MPRAGE volumes acquired within each test-retest session did not systematically improve the across-session reproducibility of morphometry estimates. Our results extend those from previous studies that showed improved reliability of the longitudinal analysis at single sites and/or with non-standard acquisition methods. The multi-site acquisition and analysis protocol presented here is promising for clinical applications since it allows for smaller sample sizes per MRI site or shorter trials in studies evaluating the role of potential biomarkers to predict disease progression or treatment effects.
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Differences in cortical development assessed by fetal MRI in late-onset intrauterine growth restriction.
Am. J. Obstet. Gynecol.
PUBLISHED: 03-06-2013
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The objective of the study was to evaluate cortical development parameters by magnetic resonance imaging (MRI) in late-onset intrauterine growth-restricted (IUGR) fetuses and normally grown fetuses.
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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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Normalization of similarity-based individual brain networks from gray matter MRI and its association with neurodevelopment in infants with intrauterine growth restriction.
Neuroimage
PUBLISHED: 02-25-2013
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Obtaining individual biomarkers for the prediction of altered neurological outcome is a challenge of modern medicine and neuroscience. Connectomics based on magnetic resonance imaging (MRI) stands as a good candidate to exhaustively extract information from MRI by integrating the information obtained in a few network features that can be used as individual biomarkers of neurological outcome. However, this approach typically requires the use of diffusion and/or functional MRI to extract individual brain networks, which require high acquisition times and present an extreme sensitivity to motion artifacts, critical problems when scanning fetuses and infants. Extraction of individual networks based on morphological similarity from gray matter is a new approach that benefits from the power of graph theory analysis to describe gray matter morphology as a large-scale morphological network from a typical clinical anatomic acquisition such as T1-weighted MRI. In the present paper we propose a methodology to normalize these large-scale morphological networks to a brain network with standardized size based on a parcellation scheme. The proposed methodology was applied to reconstruct individual brain networks of 63 one-year-old infants, 41 infants with intrauterine growth restriction (IUGR) and 22 controls, showing altered network features in the IUGR group, and their association with neurodevelopmental outcome at two years of age by means of ordinal regression analysis of the network features obtained with Bayley Scale for Infant and Toddler Development, third edition. Although it must be more widely assessed, this methodology stands as a good candidate for the development of biomarkers for altered neurodevelopment in the pediatric population.
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Donepezil treatment stabilizes functional connectivity during resting state and brain activity during memory encoding in Alzheimers disease.
J Clin Psychopharmacol
PUBLISHED: 02-21-2013
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Previous studies with functional magnetic resonance imaging (fMRI) demonstrated a differential brain activity and connectivity after treatment with donepezil in Alzheimers disease (AD) when compared to healthy elders. Importantly however, there are no available studies where the placebo or control group included comparable AD patients relative to the treated groups. Fifteen patients recently diagnosed of AD were randomized to treatment (n = 8) or to control group (n = 7); the former receiving daily treatment of donepezil during 3 months. At baseline and follow-up, both groups underwent resting-state as well as task-fMRI examinations, this latter assessing encoding of visual scenes. The treated group showed higher connectivity in areas of the default mode network, namely the right parahippocampal gyrus at follow-up resting-fMRI as compared to the control group. On the other hand, for the task-fMRI, the untreated AD group presented progressive increased activation in the left middle temporal gyrus and bilateral precuneus at the 3-month examination compared to baseline, whereas the treated group exhibited stable patterns of brain activity. Donepezil treatment is associated with stabilization of connectivity of medial temporal regions during resting state and of brain efficiency during a cognitive demand, on the whole reducing progressive dysfunctional reorganizations observed during the natural course of the disease.
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Oxidative stress markers in the neocortex of drug-resistant epilepsy patients submitted to epilepsy surgery.
Epilepsy Res.
PUBLISHED: 02-19-2013
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While there is solid experimental evidence of brain oxidative stress in animal models of epilepsy, it has not been thoroughly verified in epileptic human brain. Our purpose was to determine and to compare oxidative stress markers in the neocortex of epileptic and non-epileptic humans, with the final objective of confirming oxidative stress phenomena in human epileptic brain.
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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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Identifying the cortical substrates of interictal epileptiform activity in patients with extratemporal epilepsy: An EEG-fMRI sequential analysis and FDG-PET study.
Epilepsia
PUBLISHED: 01-30-2013
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The aim of this study was to apply sequential analysis of electroencephalography-functional magnetic resonance imaging (EEG-fMRI) data to study the cortical substrates related to the generation of the interictal epileptiform activity (IEA) in patients with pharmacoresistant extratemporal epilepsy.
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Regional gray matter reductions are associated with genetic liability for anxiety and depression: an MRI twin study.
J Affect Disord
PUBLISHED: 01-24-2013
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The influence of genetic and/or environmental factors on the volumetric brain changes observed in subjects affected by anxiety and depression disorders remains unclear. The current study aimed to investigate whether genetic and environmental liabilities make different contributions to abnormalities in gray matter volume (GMV) in anxiety and depression using a concordant and discordant MZ twin pairs design.
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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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Automatic quantitative MRI texture analysis in small-for-gestational-age fetuses discriminates abnormal neonatal neurobehavior.
PLoS ONE
PUBLISHED: 01-01-2013
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We tested the hypothesis whether texture analysis (TA) from MR images could identify patterns associated with an abnormal neurobehavior in small for gestational age (SGA) neonates.
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Validation of FDG-PET/MRI coregistration in nonlesional refractory childhood epilepsy.
Epilepsia
PUBLISHED: 11-02-2011
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To validate the use of 18F-fluorodeoxyglucose-positron emission tomography/magnetic resonance imaging (FDG-PET/MRI) coregistration for epileptogenic zone detection in children with MRI nonlesional refractory epilepsy and to assess its ability to guide a second interpretation of the MRI studies.
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Eicosanoid levels in the neocortex of drug-resistant epileptic patients submitted to epilepsy surgery.
Epilepsy Res.
PUBLISHED: 07-26-2011
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There is an increasing body of evidence implicating eicosanoids (arachidonic acid metabolites) in the experimental generation of epileptic seizures and the development of epilepsy. Our purpose was to measure the synthesis of eicosanoids from the cyclooxygenase and lipoxygenase pathways in human brain neocortex tissue samples obtained from epileptic patients, and to compare them with non-epileptic control subjects. Epileptic neocortex specimens demonstrated a significant increase (P<0.001) in the levels of three eicosanoids derived from the cyclooxygenase pathway: Prostaglandin E(2) (PGE(2)), Thromboxane A(2) (TXA(2)), and Prostacyclin (PGI(2)), compared to controls. In the epileptic samples the level of TXA(2) was twice as much the levels of PGI(2), while in the control samples the levels of PGI(2) were slightly higher than TXA(2). Conversely, there were no detectable levels of eicosanoids derived from the lipoxygenase pathway: Leukotriene B(4) (LTB(4)) and Leukotriene C(4) (LTC(4)). The lack of leukotrienes synthesis illustrates that COX pathway is dominant in neocortex of epileptic patients. Our human data are consistent with the results obtained in experimental animal models of epilepsy. The important increase in PGE(2) and TXA(2) suggests that selective inhibition of prostanoid synthesis or blockage of prostanoid receptors might provide novel antiepileptic strategies in human epilepsy.
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Functional neuroimaging in startle epilepsy: involvement of a mesial frontoparietal network.
Epilepsia
PUBLISHED: 07-19-2011
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Startle epilepsy is a rare form of epilepsy with seizures triggered by unexpected stimuli. Previous studies have suggested the participation of several brain regions, such as the supplementary motor area (SMA) or the mesial aspect of the frontal and parietal lobes in the generation of startle epilepsy. However, how these brain regions interact with each other during seizures remains largely unknown. The aim of this study was to get insight into brain structures involved in startle-induced seizures using an approach with functional neuroimaging.
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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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Seizure frequency and social outcome in drug resistant epilepsy patients who do not undergo epilepsy surgery.
Seizure
PUBLISHED: 04-08-2011
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Little is known about the long term prognosis of refractory epilepsy patients who do not undergo epilepsy surgery. We performed a telephone survey and chart review of patients who underwent presurgical evaluation in our Unit but did not have surgery, from 1998 until 2004. We contacted 84 patients; mean follow-up was 6.7 years. Four patients (4.7%) had died, presumably of SUDEP. Ten patients (13.1%) were seizure free. In most patients with seizures, frequency remained stable (24/80, 30%) or had decreased by ?50% (26 patients, 30.9%). Most patients (69, 86.2%) believed their health was similar or better respect to the moment they underwent presurgical evaluation. Employment situation was stable in 64/80 patients (80%), but 11 had received new disability wages. Family situation was also generally unchanged (69/80 patients, 86.2%). Most patients were not taking antidepressants. Seizure free patients scored higher in satisfaction with life. This information can be used to counsel refractory patients.
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A voxel-based morphometric MRI study of stabilized obsessive-compulsive adolescent patients.
Prog. Neuropsychopharmacol. Biol. Psychiatry
PUBLISHED: 03-15-2011
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The aim of this study was to determine whether treated stabilized adolescents with obsessive-compulsive disorder (OCD) present brain structure differences in comparison with healthy control subjects.
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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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Are patients referred for presurgical evaluation drug resistant according to the new consensus definition? A study in a tertiary center.
Epilepsy Res.
PUBLISHED: 03-02-2011
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We performed a retrospective chart review of the last consecutive 40 patients admitted in our Epilepsy Unit for presurgical evaluation to find out if they met criteria for drug resistant epilepsy according to the recently published consensus definition. 276 drug trials had been performed in the 40 patients. In total, 196 trials were considered "uninformative" versus 80 informative and adequate trials. Finally, a firm diagnosis of drug resistant epilepsy could be made only in 13/40 patients (32.5%, 90% confidence interval for proportion 21.7-45.5%), due to insufficient information regarding previous drug trials. The definition should be spread among general neurologists for earlier and more complete referrals.
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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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Structural brain changes and cognition in relation to markers of vascular dysfunction.
Neurobiol. Aging
PUBLISHED: 02-04-2011
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The aim was to investigate the relationship between blood markers of vascular dysfunction with brain microstructural changes and cognition. Eighty-six participants from the Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) neuropsychology study were included. Subjects were 50-65 years old, free from dementia and without history of vascular disease. We assessed correlations of blood levels of inflammatory biomarkers (C-reactive protein [CRP] and resistin) and fibrinolysis inhibitors (plasminogen activator inhibitor-1 [PAI-1] and A-lipoprotein (Lp (a)) with fractional anisotropy (FA) measurements of diffusion tensor images (DTI), regional gray matter (GM) volumes and performance in several cognitive domains. Increasing levels of C-reactive protein and PAI-1 levels were associated with white matter (WM) integrity loss in corticosubcortical pathways and association fibers of frontal and temporal lobes, independently of age, sex and vascular risk factors. PAI-1 was also related to lower speed and visuomotor/coordination. None of the biomarkers were related to gray matter volume changes. Our findings suggest that inflammation and dysregulation of the fibrynolitic system may be involved in the pathological mechanisms underlying the WM damage seen in cerebrovascular disease and subsequent cognitive impairment.
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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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Differential effects of intrauterine growth restriction on brain structure and development in preterm infants: a magnetic resonance imaging study.
Brain Res.
PUBLISHED: 01-10-2011
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Previous evidence suggests that preterm newborns with intrauterine growth restriction (IUGR) have specific neurostructural and neurodevelopmental anomalies, but it is unknown whether these effects persist in early childhood. We studied a sample of 18 preterm IUGR, 15 preterm AGA - born between 26 and 34 weeks of gestational age (GA) - and 15 healthy born-term infants. Infants were scanned at 12 months corrected age (CA), in a 3T scanner, without sedation. Analyses were made by automated lobar volumetry and voxel-based morphometry (VBM). The neurodevelopmental outcome was assessed in all subjects at 18 months CA with the Bayley Scale for Infant and Toddler Development, third edition. IUGR infants had reduced relative volumes for the insular and temporal lobes. According to VBM, IUGR infants had bilateral reduced gray matter (GM) in the temporal, parietal, frontal, and insular regions compared with the other groups. IUGR infants had increased white matter (WM) in temporal regions compared to the AGA group and in frontal, parietal, occipital, and insular regions compared to the term group. They also showed decreased WM in the cerebellum and a non-significant trend in the hippocampus compared to term infants. IUGR infants had reduced neurodevelopmental scores, which were positively correlated with GM in various regions. These data suggest that the IUGR induces a distinct brain pattern of structural changes that persist at 1 year of life and are associated with specific developmental difficulties.
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Efficiency of venlafaxine in patients with psychogenic nonepileptic seizures and anxiety and/or depressive disorders.
J Neuropsychiatry Clin Neurosci
PUBLISHED: 11-02-2010
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An open-label, experimental, prospective 5-month follow-up study was performed with 19 patients with psychogenic nonepileptic seizures and anxiety disorder and/or depression who were treated with venlafaxine. The authors held monthly visits and evaluated changes in baseline Hamilton Depression Rating Scale scores, Hamilton Anxiety Rating Scale scores, and the number of psychogenic nonepileptic seizures. HAM-D scores, HAM-A scores, and the number of nonepileptic seizures showed a statistically significant decrease which was maintained over the study period. Based on this study, the authors conclude that venlafaxine may help reduce nonepileptic seizures in patients with additional anxious and/or depressive symptoms.
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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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Multicenter study of brain volume abnormalities in children and adolescent-onset psychosis.
Schizophr Bull
PUBLISHED: 05-16-2010
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The goal of the study is to determine the extent of structural brain abnormalities in a multicenter sample of children and adolescents with a recent-onset first episode of psychosis (FEP), compared with a sample of healthy controls. Total brain and lobar volumes and those of gray matter (GM), white matter, and cerebrospinal fluid (CSF) were measured in 92 patients with a FEP and in 94 controls, matched for age, gender, and years of education. Male patients (n = 64) showed several significant differences when compared with controls (n = 61). GM volume in male patients was reduced in the whole brain and in frontal and parietal lobes compared with controls. Total CSF volume and frontal, temporal, and right parietal CSF volumes were also increased in male patients. Within patients, those with a further diagnosis of "schizophrenia" or "other psychosis" showed a pattern similar to the group of all patients relative to controls. However, bipolar patients showed fewer differences relative to controls. In female patients, only the schizophrenia group showed differences relative to controls, in frontal CSF. GM deficit in male patients with a first episode correlated with negative symptoms. Our study suggests that at least part of the GM deficit in children and adolescent-onset schizophrenia and in other psychosis occurs before onset of the first positive symptoms and that, contrary to what has been shown in children-onset schizophrenia, frontal GM deficits are probably present from the first appearance of positive symptoms in children and adolescents.
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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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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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Fractal-dimension analysis detects cerebral changes in preterm infants with and without intrauterine growth restriction.
Neuroimage
PUBLISHED: 04-09-2010
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In the search for a useful parameter to detect and quantify subtle brain abnormalities in infants with intrauterine growth restriction (IUGR), we hypothesised that the analysis of the structural complexity of grey matter (GM) and white matter (WM) using the fractal dimension (FD), a measurement of the topological complexity of an object, could be established as a useful tool for quantitative studies of infant brain morphology. We studied a sample of 18 singleton IUGR premature infants, (12.72 months corrected age (CA), range: 12 months-14 months), 15 preterm infants matched one-to-one for gestational age (GA) at delivery (12.6 months; range: 12 months-14 months), and 15 neonates born at term (12.4 months; range: 11 months-14 months). The neurodevelopmental outcome was assessed in all subjects at 18 months CA according to the Bayley Scale for Infant and Toddler Development - Third edition (BSID-III). For MRI acquisition and processing, the infants were scanned at 12 months CA, in a TIM TRIO 3T scanner, sleeping naturally. Images were pre-processed using the SPM5 toolbox, the GM and WM segmented under the VBM5 toolbox, and the box-counting method was applied for FD calculation of normal and skeletonized segmented images. The results showed a significant decrease of the FD of the brain GM and WM in the IUGR group when compared to the preterm or at-term controls. We also identified a significant linear tendency of both GM and WM FD from IUGR to preterm and term groups. Finally, multiple linear analyses between the FD of the GM or WM and the neurodevelopmental scales showed a significant regression of the language and motor scales with the FD of the GM. In conclusion, a decreased FD of the GM and WM in IUGR infants could be a sensitive indicator for the investigation of structural brain abnormalities in the IUGR population at 12 months of age, which can also be related to functional disorders.
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Glucose and caffeine effects on sustained attention: an exploratory fMRI study.
Hum Psychopharmacol
PUBLISHED: 03-22-2010
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Caffeine and glucose can have beneficial effects on cognitive performance. However, neural basis of these effects remain unknown. Our objective was to evaluate the effects of caffeine and glucose on sustained attention, using functional magnetic resonance imaging (fMRI).
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Increased glutamate/glutamine compounds in the brains of patients with fibromyalgia: a magnetic resonance spectroscopy study.
Arthritis Rheum.
PUBLISHED: 03-02-2010
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Fibromyalgia (FM) has been defined as a systemic disorder that is clinically characterized by pain, cognitive deficit, and the presence of associated psychopathology, all of which are suggestive of a primary brain dysfunction. This study was undertaken to identify the nature of this cerebral dysfunction by assessing the brain metabolite patterns in patients with FM through magnetic resonance spectroscopy (MRS) techniques.
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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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Prefrontal brain metabolites in short-term weight-recovered adolescent anorexia nervosa patients.
Prog. Neuropsychopharmacol. Biol. Psychiatry
PUBLISHED: 01-21-2010
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Various neuroimaging techniques have revealed morphological and functional alterations in anorexia nervosa (AN), although few spectroscopic magnetic resonance studies have examined short-term weight-recovered AN patients. Subjects were 32 female adolescent patients (between 13 and 18 years old) seen consecutively in our department and who met DSM-IV diagnostic criteria for AN. All of them had received a minimum of six months of treatment and were short-term weight-recovered (for one to three months) with a body mass index ranging from 18 to 23. A group of 20 healthy female volunteer controls of similar age were also included. All subjects were assessed with psychopathological scales and magnetic resonance spectroscopy. Total choline (Cho) (p=0.007) and creatine (Cr) (p=0.008) levels were significantly higher in AN patients than in controls. AN patients receiving psychopharmacological treatment with SSRIs (N=9) had metabolite levels similar to control subjects, but patients without this treatment did not. The present study shows abnormalities in brain neurometabolites related to Cho compounds and Cr in the prefrontal cortex in short-term weight-recovered adolescent AN patients, principally in patients not undergoing psychopharmacological treatment. More studies with larger samples are necessary to test the generalizability of the present results.
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Prevalence of interictal psychiatric disorders in patients with refractory temporal and extratemporal lobe epilepsy in Spain. A comparative study.
Epilepsia
PUBLISHED: 12-22-2009
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We aim to investigate whether temporal origin of epilepsy increases the risk of developing a psychiatric disorder and more specifically a major depressive disorder. The lack of standardized diagnostic instruments and the methodologic differences between studies highlight the fact that this issue warrants further, systematic, study. Three-hundred eight patients with complex partial seizures were classified according to temporal or extratemporal origin, following the Commission on Classification and Terminology of the International League Against Epilepsy (ILAE), 1989 localization-related concept. All patients were assessed using the Structured Interview for DSM-IV axis I psychiatric disorders (SCID-I). Lifetime and previous-year prevalence of psychiatric disorders were compared in temporal and extratemporal subgroups, using multivariate analysis. Previous-year major depression was significantly associated with temporal lobe origin. Our results do not support the hypothesis that patients with temporal lobe epilepsy (TLE) have more psychiatric illness in general, although they do suggest a specific connection between TLE and major depression.
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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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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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Progressive gray matter changes in first episode schizophrenia: a 4-year longitudinal magnetic resonance study using VBM.
Schizophr. Res.
PUBLISHED: 07-15-2009
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Schizophrenia is a disabling illness, characterized by a heterogeneous course including clinical deterioration and poor outcome. Accumulating findings in schizophrenia suggest that it might involve two pathophysiologic processes, one early in life (neurodevelopmental), and one after onset of the illness (neurodegenerative). Longitudinal imaging studies after onset of the illness may help to clarify these pathophysiological aspects of schizophrenia, but so far, probably due to methodological differences, there have been no conclusive results. The present study sets out to investigate longitudinal gray matter changes in patients with first-episode schizophrenia relative to healthy subjects over the first 4 years of the illness and the relation of gray matter changes in patients with functional outcome, using an objective automatic method not biased to one particular structure to analyze gray matter changes.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

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We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.