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Find video protocols related to scientific articles indexed in Pubmed.
The comprehensive neuro-oncology data repository (CONDR): a research infrastructure to develop and validate imaging biomarkers.
Neurosurgery
PUBLISHED: 09-05-2014
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Advanced imaging methods have the potential to serve as quantitative biomarkers in neuro-oncology research. However, a lack of standardization of image acquisition, processing, and analysis limits their application in clinical research. Standardization of these methods and an organized archival platform are required to better validate and apply these markers in research settings and, ultimately, in clinical practice.
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The freedom to heal: nonrigid immobilization by a halo orthosis.
J Neurosurg Spine
PUBLISHED: 08-22-2014
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Halo orthoses present a paradox. On the one hand, the nominally rigid immobilization they provide to the head aims to remove loads on the cervical spine following injury or surgery, and the devices are retightened routinely to maintain this. On the other hand, bone growth and remodeling are well known to require mechanical stressing. How are these competing needs balanced? To understand this trade-off in an effective, commercial halo orthosis, the authors quantified the response of a commercial halo orthosis to physiological loading levels, applied symmetrically about the sagittal plane. They showed for the first time that after a few cycles of loading analogous to a few steps taken by a patient, the support presented by a standard commercial halo orthosis becomes nonlinear. When analyzed through straightforward structural modeling, these data revealed that the nonlinearity permits mild head motion while severely restricting larger motion. These observations are useful because they open the possibility that halo orthosis installation could be optimized to transfer mild spinal loads that support healing while blocking pathological loads.
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Management of atypical cranial meningiomas, part 2: predictors of progression and the role of adjuvant radiation after subtotal resection.
Neurosurgery
PUBLISHED: 06-17-2014
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The efficacies of adjuvant stereotactic radiosurgery (SRS) and external beam radiation therapy (EBRT) for atypical meningiomas (AMs) after subtotal resection (STR) remain unclear.
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Radiation Therapy Dose Escalation for Glioblastoma Multiforme in the Era of Temozolomide.
Int. J. Radiat. Oncol. Biol. Phys.
PUBLISHED: 04-06-2014
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To review clinical outcomes of moderate dose escalation using high-dose radiation therapy (HDRT) in the setting of concurrent temozolomide (TMZ) in patients with newly diagnosed glioblastoma multiforme (GBM), compared with standard-dose radiation therapy (SDRT).
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Characterization of the effects of the human dura on macro- and micro-electrocorticographic recordings.
J Neural Eng
PUBLISHED: 03-22-2014
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Electrocorticography (ECoG) electrodes implanted on the surface of the brain have recently emerged as a potential signal platform for brain-computer interface (BCI) systems. While clinical ECoG electrodes are currently implanted beneath the dura, epidural electrodes could reduce the invasiveness and the potential impact of a surgical site infection. Subdural electrodes, on the other hand, while slightly more invasive, may have better signals for BCI application. Because of this balance between risk and benefit between the two electrode positions, the effect of the dura on signal quality must be determined in order to define the optimal implementation for an ECoG BCI system.
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Fast-scale network dynamics in human cortex have specific spectral covariance patterns.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 03-10-2014
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Whether measured by MRI or direct cortical physiology, infraslow rhythms have defined state invariant cortical networks. The time scales of this functional architecture, however, are unlikely to be able to accommodate the more rapid cortical dynamics necessary for an active cognitive task. Using invasively monitored epileptic patients as a research model, we tested the hypothesis that faster frequencies would spectrally bind regions of cortex as a transient mechanism to enable fast network interactions during the performance of a simple hear-and-repeat speech task. We term these short-lived spectrally covariant networks functional spectral networks (FSNs). We evaluated whether spectrally covariant regions of cortex, which were unique in their spectral signatures, provided a higher degree of task-related information than any single site showing more classic physiologic responses (i.e., single-site amplitude modulation). Taken together, our results showing that FSNs are a more sensitive measure of task-related brain activation and are better able to discern phonemic content strongly support the concept of spectrally encoded interactions in cortex. Moreover, these findings that specific linguistic information is represented in FSNs that have broad anatomic topographies support a more distributed model of cortical processing.
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The role of laser interstitial thermal therapy in enhancing progression-free survival of difficult-to-access high-grade gliomas: a multicenter study.
Cancer Med
PUBLISHED: 02-05-2014
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Surgical extent-of-resection has been shown to have an impact on high-grade glioma (HGG) outcomes; however, complete resection is rarely achievable in difficult-to-access (DTA) tumors. Controlled thermal damage to the tumor may have the same impact in DTA-HGGs. We report our multicenter results of laser interstitial thermal therapy (LITT) in DTA-HGGs. We retrospectively reviewed 34 consecutive DTA-HGG patients (24 glioblastoma, 10 anaplastic) who underwent LITT at Cleveland Clinic, Washington University, and Wake Forest University (May 2011-December 2012) using the NeuroBlate(®) System. The extent of thermal damage was determined using thermal damage threshold (TDT) lines: yellow TDT line (43 °C for 2 min) and blue TDT line (43°C for 10 min). Volumetric analysis was performed to determine the extent-of-coverage of tumor volume by TDT lines. Patient outcomes were evaluated statistically. LITT was delivered as upfront in 19 and delivered as salvage in 16 cases. After 7.2 months of follow-up, 71% of cases demonstrated progression and 34% died. The median overall survival (OS) for the cohort was not reached; however, the 1-year estimate of OS was 68 ± 9%. Median progression-free survival (PFS) was 5.1 months. Thirteen cases who met the following two criteria-(1) <0.05 cm(3) tumor volume not covered by the yellow TDT line and (2) <1.5 cm(3) additional tumor volume not covered by the blue TDT line-had better PFS than the other 21 cases (9.7 vs. 4.6 months; P = 0.02). LITT can be used effectively for treatment of DTA-HGGs. More complete coverage of tumor by TDT lines improves PFS which can be translated as the extent of resection concept for surgery.
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Laser Ablation as Treatment Strategy for Medically Refractory Dominant Insular Epilepsy: Therapeutic and Functional Considerations.
Stereotact Funct Neurosurg
PUBLISHED: 01-22-2014
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Since its introduction to neurosurgery in 2008, laser ablative techniques have been largely confined to the management of unresectable tumors. Application of this technology for the management of focal epilepsy in the adult population has not been fully explored. Given that nearly 1,000,000 Americans live with medically refractory epilepsy and current surgical techniques only address a fraction of epileptic pathologies, additional therapeutic options are needed. We report the successful treatment of dominant insular epilepsy in a 53-year-old male with minimally invasive laser ablation complicated by mild verbal and memory deficits. We also report neuropsychological test data on this patient before surgery and at 8 months after the ablation procedure. This account represents the first reported successful patient outcome of laser ablation as an effective treatment option for medically refractory post-stroke epilepsy in an adult. © 2014 S. Karger AG, Basel.
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Predictors of individual tumor local control after stereotactic radiosurgery for non-small cell lung cancer brain metastases.
Int. J. Radiat. Oncol. Biol. Phys.
PUBLISHED: 01-14-2014
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To evaluate local control rates and predictors of individual tumor local control for brain metastases from non-small cell lung cancer (NSCLC) treated with stereotactic radiosurgery (SRS).
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The role of resting state networks in focal neocortical seizures.
PLoS ONE
PUBLISHED: 01-01-2014
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The role of resting state functional networks in epilepsy is incompletely understood. While some pathologic diagnoses have been shown to have maintained but altered resting state connectivity, others have implicated resting state connectivity in disease progression. However little is known about how these resting state networks influence the behavior of a focal neocortical seizure.
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Codeletions at 1p and 19q predict a lower risk of pseudoprogression in oligodendrogliomas and mixed oligoastrocytomas.
Neuro-oncology
PUBLISHED: 11-26-2013
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Background Pseudoprogression (PsP) occurs at a higher rate in glioblastoma multiforme with a methylated MGMT promoter-a subset with increased sensitivity to chemoradiotherapy and better overall prognosis. In oligodendroglioma (OG) and oligoastrocytoma (OA), presence of 1p/19q codeletions is highly predictive of response to treatment and is often associated with the methylated MGMT promoter; hence, this study queries whether the presence of 1p/19q codeletions in OG/OA correlates with a higher rate of PsP following therapy. Methods A retrospective analysis was performed on all OG/OA in a database of patients with brain tumors who underwent resection of their tumor since 1998. Eighty-eight cases (37 with and 51 without 1p/19q codeletions) met inclusion criteria, and their patient data were analyzed to determine whether the presence of 1p/19q codeletions was associated with PsP and survival. Results OG/OA (World Health Organization grades II and III) with 1p/19q codeletions had a significantly improved survival (P = .041). Multivariate analysis found that PsP occurred less frequently in OG/OA with 1p/19q codeletions compared with tumors without codeletions (odds ratio, 0.047; 95% confidence interval, 0.005-0.426; P = .0066). The rate of PsP was 19% for the entire cohort, 31% for tumors without codeletions, and 3% for tumors with codeletions. When early posttreatment contrast enhancement developed in tumors with 1p/19q codeletions, it occurred exclusively in tumors that were histologically OA and not OG. Conclusion Codeletions of 1p/19q are a marker of good prognosis but are unexpectedly associated with a lower likelihood of PsP. PsP does not correlate with sensitivity to treatment and improved survival in OG/OA.
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A novel data-driven approach to preoperative mapping of functional cortex using resting-state functional magnetic resonance imaging.
Neurosurgery
PUBLISHED: 11-23-2013
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Recent findings associated with resting-state cortical networks have provided insight into the brains organizational structure. In addition to their neuroscientific implications, the networks identified by resting-state functional magnetic resonance imaging (rs-fMRI) may prove useful for clinical brain mapping.
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Frequency-specific mechanism links human brain networks for spatial attention.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 11-11-2013
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Selective attention allows us to filter out irrelevant information in the environment and focus neural resources on information relevant to our current goals. Functional brain-imaging studies have identified networks of broadly distributed brain regions that are recruited during different attention processes; however, the dynamics by which these networks enable selection are not well understood. Here, we first used functional MRI to localize dorsal and ventral attention networks in human epileptic subjects undergoing seizure monitoring. We subsequently recorded cortical physiology using subdural electrocorticography during a spatial-attention task to study network dynamics. Attention networks become selectively phase-modulated at low frequencies (?, ?) during the same task epochs in which they are recruited in functional MRI. This mechanism may alter the excitability of task-relevant regions or their effective connectivity. Furthermore, different attention processes (holding vs. shifting attention) are associated with synchrony at different frequencies, which may minimize unnecessary cross-talk between separate neuronal processes.
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Magnetic resonance imaging-guided focused laser interstitial thermal therapy for intracranial lesions: single-institution series.
Neurosurgery
PUBLISHED: 09-24-2013
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Surgical treatments for deep-seated intracranial lesions have been limited by morbidities associated with resection. Real-time magnetic resonance imaging-guided focused laser interstitial thermal therapy (LITT) offers a minimally invasive surgical treatment option for such lesions.
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Resting state network estimation in individual subjects.
Neuroimage
PUBLISHED: 05-21-2013
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Resting state functional magnetic resonance imaging (fMRI) has been used to study brain networks associated with both normal and pathological cognitive functions. The objective of this work is to reliably compute resting state network (RSN) topography in single participants. We trained a supervised classifier (multi-layer perceptron; MLP) to associate blood oxygen level dependent (BOLD) correlation maps corresponding to pre-defined seeds with specific RSN identities. Hard classification of maps obtained from a priori seeds was highly reliable across new participants. Interestingly, continuous estimates of RSN membership retained substantial residual error. This result is consistent with the view that RSNs are hierarchically organized, and therefore not fully separable into spatially independent components. After training on a priori seed-based maps, we propagated voxel-wise correlation maps through the MLP to produce estimates of RSN membership throughout the brain. The MLP generated RSN topography estimates in individuals consistent with previous studies, even in brain regions not represented in the training data. This method could be used in future studies to relate RSN topography to other measures of functional brain organization (e.g., task-evoked responses, stimulation mapping, and deficits associated with lesions) in individuals. The multi-layer perceptron was directly compared to two alternative voxel classification procedures, specifically, dual regression and linear discriminant analysis; the perceptron generated more spatially specific RSN maps than either alternative.
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Biopsy of the superficial cortex: predictors of effectiveness and outcomes.
Neurosurgery
PUBLISHED: 05-02-2013
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Brain biopsies of superficial cortex are performed for diagnosis of neurological diseases, but preoperative predictors of successful diagnosis and risks are lacking.
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Trans-middle temporal gyrus selective amygdalohippocampectomy for medically intractable mesial temporal lobe epilepsy in adults: seizure response rates, complications, and neuropsychological outcomes.
Epilepsy Behav
PUBLISHED: 01-24-2013
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Selective amygdalohippocampectomy (AHC) has evolved to encompass a variety of techniques to resect the mesial temporal lobe. To date, there have been few large-scale evaluations of trans-middle temporal gyrus selective AHC. The authors examine a large series of patients who have undergone the trans-middle temporal gyrus AHC and assess its clinical and neuropsychological impact.
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Developing a new model for the invention and translation of neurotechnologies in academic neurosurgery.
Neurosurgery
PUBLISHED: 01-04-2013
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There is currently an acceleration of new scientific and technical capabilities that create new opportunities for academic neurosurgery. To engage these changing dynamics, the Center for Innovation in Neuroscience and Technology (CINT) was created on the premise that successful innovation of device-related ideas relies on collaboration between multiple disciplines. The CINT has created a unique model that integrates scientific, medical, engineering, and legal/business experts to participate in the continuum from idea generation to translation.
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Brain mapping in a patient with congenital blindness - a case for multimodal approaches.
Front Hum Neurosci
PUBLISHED: 01-01-2013
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Recent advances in basic neuroscience research across a wide range of methodologies have contributed significantly to our understanding of human cortical electrophysiology and functional brain imaging. Translation of this research into clinical neurosurgery has opened doors for advanced mapping of functionality that previously was prohibitively difficult, if not impossible. Here we present the case of a unique individual with congenital blindness and medically refractory epilepsy who underwent neurosurgical treatment of her seizures. Pre-operative evaluation presented the challenge of accurately and robustly mapping the cerebral cortex for an individual with a high probability of significant cortical re-organization. Additionally, a blind individual has unique priorities in ones ability to read Braille by touch and sense the environment primarily by sound than the non-vision impaired person. For these reasons we employed additional measures to map sensory, motor, speech, language, and auditory perception by employing a number of cortical electrophysiologic mapping and functional magnetic resonance imaging methods. Our data show promising results in the application of these adjunctive methods in the pre-operative mapping of otherwise difficult to localize, and highly variable, functional cortical areas.
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Transient hemispatial neglect after surgical resection of a right frontal lobe mass.
World Neurosurg
PUBLISHED: 10-12-2011
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Hemispatial neglect is classically associated with damage to the inferior parietal lobule of the right hemisphere, but is also infrequently linked with damage to the frontal lobe. A patient with contralateral hemispatial neglect after surgical resection of a right posterior inferior frontal lobe mass is described.
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Brain-computer interfaces using electrocorticographic signals.
IEEE Rev Biomed Eng
PUBLISHED: 09-02-2011
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Many studies over the past two decades have shown that people and animals can use brain signals to convey their intent to a computer using brain-computer interfaces (BCIs). BCI systems measure specific features of brain activity and translate them into control signals that drive an output. The sensor modalities that have most commonly been used in BCI studies have been electroencephalographic (EEG) recordings from the scalp and single-neuron recordings from within the cortex. Over the past decade, an increasing number of studies has explored the use of electrocorticographic (ECoG) activity recorded directly from the surface of the brain. ECoG has attracted substantial and increasing interest, because it has been shown to reflect specific details of actual and imagined actions, and because its technical characteristics should readily support robust and chronic implementations of BCI systems in humans. This review provides general perspectives on the ECoG platform; describes the different electrophysiological features that can be detected in ECoG; elaborates on the signal acquisition issues, protocols, and online performance of ECoG-based BCI studies to date; presents important limitations of current ECoG studies; discusses opportunities for further research; and finally presents a vision for eventual clinical implementation. In summary, the studies presented to date strongly encourage further research using the ECoG platform for basic neuroscientific research, as well as for translational neuroprosthetic applications.
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An EEG-based brain computer interface for rehabilitation and restoration of hand control following stroke using ipsilateral cortical physiology.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 08-29-2011
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The loss of motor control severely impedes activities of daily life. Brain computer interfaces (BCIs) offer new possibilities to treat nervous system injuries, but conventional BCIs use signals from primary motor cortex, the same sites most likely damaged in a stroke causing paralysis. Recent studies found distinct cortical physiology associated with contralesional limb movements in regions distinct from primary motor cortex. To capitalize on these findings, we designed and implemented a BCI that localizes and acquires these brain signals to drive a powered, hand orthotic which opens and closes a patients hand.
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Decoding vowels and consonants in spoken and imagined words using electrocorticographic signals in humans.
J Neural Eng
PUBLISHED: 07-13-2011
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Several stories in the popular media have speculated that it may be possible to infer from the brain which word a person is speaking or even thinking. While recent studies have demonstrated that brain signals can give detailed information about actual and imagined actions, such as different types of limb movements or spoken words, concrete experimental evidence for the possibility to read the mind, i.e. to interpret internally-generated speech, has been scarce. In this study, we found that it is possible to use signals recorded from the surface of the brain (electrocorticography) to discriminate the vowels and consonants embedded in spoken and in imagined words, and we defined the cortical areas that held the most information about discrimination of vowels and consonants. The results shed light on the distinct mechanisms associated with production of vowels and consonants, and could provide the basis for brain-based communication using imagined speech.
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Decoding motor signals from the pediatric cortex: implications for brain-computer interfaces in children.
Pediatrics
PUBLISHED: 06-20-2011
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To demonstrate the decodable nature of pediatric brain signals for the purpose of neuroprosthetic control. We hypothesized that children would achieve levels of brain-derived computer control comparable to performance previously reported for adults.
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The effect of age on human motor electrocorticographic signals and implications for brain-computer interface applications.
J Neural Eng
PUBLISHED: 06-10-2011
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Electrocorticography (ECoG)-based brain-computer interface (BCI) systems have emerged as a new signal platform for neuroprosthetic application. ECoG-based platforms have shown significant promise for clinical application due to the high level of information that can be derived from the ECoG signal, the signals stability, and its intermediate nature of surgical invasiveness. However, before long-term BCI applications can be realized it will be important to also understand how the cortical physiology alters with age. Such understanding may provide an appreciation for how this may affect the control signals utilized by a chronic implant. In this study, we report on a large population of adult and pediatric invasively monitored subjects to determine the impact that age will have on surface cortical physiology. We evaluated six frequency bands--delta (<4 Hz), theta (4-8 Hz), alpha (8-13 Hz), beta (13-30 Hz), low gamma band (30-50 Hz), and high gamma band (76-100 Hz)--to evaluate the effect of age on the magnitude of power change, cortical area of activation, and cortical networks. When significant trends are evaluated as a whole, it appears that the aging process appears to more substantively alter thalamocortical interactions leading to an increase in cortical inefficiency. Despite this, we find that higher gamma rhythms appear to be more anatomically constrained with age, while lower frequency rhythms appear to broaden in cortical involvement as time progresses. From an independent signal standpoint, this would favor high gamma rhythms utilization as a separable signal that could be maintained chronically.
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Use of movable high-field-strength intraoperative magnetic resonance imaging with awake craniotomies for resection of gliomas: preliminary experience.
Neurosurgery
PUBLISHED: 04-19-2011
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Awake craniotomy with electrocortical mapping and intraoperative magnetic resonance imaging (iMRI) are established techniques for maximizing tumor resection and preserving function, but there has been little experience combining these methodologies.
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Using the electrocorticographic speech network to control a brain-computer interface in humans.
J Neural Eng
PUBLISHED: 04-07-2011
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Electrocorticography (ECoG) has emerged as a new signal platform for brain-computer interface (BCI) systems. Classically, the cortical physiology that has been commonly investigated and utilized for device control in humans has been brain signals from the sensorimotor cortex. Hence, it was unknown whether other neurophysiological substrates, such as the speech network, could be used to further improve on or complement existing motor-based control paradigms. We demonstrate here for the first time that ECoG signals associated with different overt and imagined phoneme articulation can enable invasively monitored human patients to control a one-dimensional computer cursor rapidly and accurately. This phonetic content was distinguishable within higher gamma frequency oscillations and enabled users to achieve final target accuracies between 68% and 91% within 15 min. Additionally, one of the patients achieved robust control using recordings from a microarray consisting of 1 mm spaced microwires. These findings suggest that the cortical network associated with speech could provide an additional cognitive and physiologic substrate for BCI operation and that these signals can be acquired from a cortical array that is small and minimally invasive.
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Neural correlates of visual-spatial attention in electrocorticographic signals in humans.
Front Hum Neurosci
PUBLISHED: 04-06-2011
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Attention is a cognitive selection mechanism that allocates the limited processing resources of the brain to the sensory streams most relevant to our immediate goals, thereby enhancing responsiveness and behavioral performance. The underlying neural mechanisms of orienting attention are distributed across a widespread cortical network. While aspects of this network have been extensively studied, details about the electrophysiological dynamics of this network are scarce. In this study, we investigated attentional networks using electrocorticographic (ECoG) recordings from the surface of the brain, which combine broad spatial coverage with high temporal resolution, in five human subjects. ECoG was recorded when subjects covertly attended to a spatial location and responded to contrast changes in the presence of distractors in a modified Posner cueing task. ECoG amplitudes in the alpha, beta, and gamma bands identified neural changes associated with covert attention and motor preparation/execution in the different stages of the task. The results show that attentional engagement was primarily associated with ECoG activity in the visual, prefrontal, premotor, and parietal cortices. Motor preparation/execution was associated with ECoG activity in premotor/sensorimotor cortices. In summary, our results illustrate rich and distributed cortical dynamics that are associated with orienting attention and the subsequent motor preparation and execution. These findings are largely consistent with and expand on primate studies using intracortical recordings and human functional neuroimaging studies.
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Implementation and preliminary clinical experience with the use of ceiling mounted mobile high field intraoperative magnetic resonance imaging between two operating rooms.
Acta Neurochir. Suppl.
PUBLISHED: 02-25-2011
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Intraoperative magnetic resonance imaging (ioMRI) provides immediate feedback and quality assurance enabling the neurosurgeon to improve the quality of a range of neurosurgical procedures. Implementation of ioMRI is a complex and costly process. We describe our preliminary 16 months experience with the integration of an IMRIS movable ceiling mounted high field (1.5 T) ioMRI setup with two operating rooms.
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Nonuniform high-gamma (60-500 Hz) power changes dissociate cognitive task and anatomy in human cortex.
J. Neurosci.
PUBLISHED: 02-11-2011
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High-gamma-band (>60 Hz) power changes in cortical electrophysiology are a reliable indicator of focal, event-related cortical activity. Despite discoveries of oscillatory subthreshold and synchronous suprathreshold activity at the cellular level, there is an increasingly popular view that high-gamma-band amplitude changes recorded from cellular ensembles are the result of asynchronous firing activity that yields wideband and uniform power increases. Others have demonstrated independence of power changes in the low- and high-gamma bands, but to date, no studies have shown evidence of any such independence above 60 Hz. Based on nonuniformities in time-frequency analyses of electrocorticographic (ECoG) signals, we hypothesized that induced high-gamma-band (60-500 Hz) power changes are more heterogeneous than currently understood. Using single-word repetition tasks in six human subjects, we showed that functional responsiveness of different ECoG high-gamma sub-bands can discriminate cognitive task (e.g., hearing, reading, speaking) and cortical locations. Power changes in these sub-bands of the high-gamma range are consistently present within single trials and have statistically different time courses within the trial structure. Moreover, when consolidated across all subjects within three task-relevant anatomic regions (sensorimotor, Brocas area, and superior temporal gyrus), these behavior- and location-dependent power changes evidenced nonuniform trends across the population. Together, the independence and nonuniformity of power changes across a broad range of frequencies suggest that a new approach to evaluating high-gamma-band cortical activity is necessary. These findings show that in addition to time and location, frequency is another fundamental dimension of high-gamma dynamics.
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Stable and dynamic cortical electrophysiology of induction and emergence with propofol anesthesia.
Proc. Natl. Acad. Sci. U.S.A.
PUBLISHED: 11-15-2010
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The mechanism(s) by which anesthetics reversibly suppress consciousness are incompletely understood. Previous functional imaging studies demonstrated dynamic changes in thalamic and cortical metabolic activity, as well as the maintained presence of metabolically defined functional networks despite the loss of consciousness. However, the invasive electrophysiology associated with these observations has yet to be studied. By recording electrical activity directly from the cortical surface, electrocorticography (ECoG) provides a powerful method to integrate spatial, temporal, and spectral features of cortical electrophysiology not possible with noninvasive approaches. In this study, we report a unique comprehensive recording of invasive human cortical physiology during both induction and emergence from propofol anesthesia. Propofol-induced transitions in and out of consciousness (defined here as responsiveness) were characterized by maintained large-scale functional networks defined by correlated fluctuations of the slow cortical potential (<0.5 Hz) over the somatomotor cortex, present even in the deeply anesthetized state of burst suppression. Similarly, phase-power coupling between ?- and ?-range frequencies persisted throughout the induction and emergence from anesthesia. Superimposed on this preserved functional architecture were alterations in frequency band power, variance, covariance, and phase-power interactions that were distinct to different frequency ranges and occurred in separable phases. These data support that dynamic alterations in cortical and thalamocortical circuit activity occur in the context of a larger stable architecture that is maintained despite anesthetic-induced alterations in consciousness.
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Proceedings of the first international workshop on advances in electrocorticography.
Epilepsy Behav
PUBLISHED: 08-20-2010
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In October 2009, a group of neurologists, neurosurgeons, computational neuroscientists, and engineers congregated to present novel developments transforming human electrocorticography (ECoG) beyond its established relevance in clinical epileptology. The contents of the proceedings advanced the role of ECoG in seizure detection and prediction, neurobehavioral research, functional mapping, and brain-computer interface technology. The meeting established the foundation for future work on the methodology and application of surface brain recordings.
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Dynamic modulation of local population activity by rhythm phase in human occipital cortex during a visual search task.
Front Hum Neurosci
PUBLISHED: 07-26-2010
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Brain rhythms are more than just passive phenomena in visual cortex. For the first time, we show that the physiology underlying brain rhythms actively suppresses and releases cortical areas on a second-to-second basis during visual processing. Furthermore, their influence is specific at the scale of individual gyri. We quantified the interaction between broadband spectral change and brain rhythms on a second-to-second basis in electrocorticographic (ECoG) measurement of brain surface potentials in five human subjects during a visual search task. Comparison of visual search epochs with a blank screen baseline revealed changes in the raw potential, the amplitude of rhythmic activity, and in the decoupled broadband spectral amplitude. We present new methods to characterize the intensity and preferred phase of coupling between broadband power and band-limited rhythms, and to estimate the magnitude of rhythm-to-broadband modulation on a trial-by-trial basis. These tools revealed numerous coupling motifs between the phase of low-frequency (?, ?, ?, ?, and ? band) rhythms and the amplitude of broadband spectral change. In the ? and ? ranges, the coupling of phase to broadband change is dynamic during visual processing, decreasing in some occipital areas and increasing in others, in a gyrally specific pattern. Finally, we demonstrate that the rhythms interact with one another across frequency ranges, and across cortical sites.
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Spatiotemporal dynamics of electrocorticographic high gamma activity during overt and covert word repetition.
Neuroimage
PUBLISHED: 04-27-2010
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Language is one of the defining abilities of humans. Many studies have characterized the neural correlates of different aspects of language processing. However, the imaging techniques typically used in these studies were limited in either their temporal or spatial resolution. Electrocorticographic (ECoG) recordings from the surface of the brain combine high spatial with high temporal resolution and thus could be a valuable tool for the study of neural correlates of language function. In this study, we defined the spatiotemporal dynamics of ECoG activity during a word repetition task in nine human subjects. ECoG was recorded while each subject overtly or covertly repeated words that were presented either visually or auditorily. ECoG amplitudes in the high gamma (HG) band confidently tracked neural changes associated with stimulus presentation and with the subjects verbal response. Overt word production was primarily associated with HG changes in the superior and middle parts of temporal lobe, Wernickes area, the supramarginal gyrus, Brocas area, premotor cortex (PMC), primary motor cortex. Covert word production was primarily associated with HG changes in superior temporal lobe and the supramarginal gyrus. Acoustic processing from both auditory stimuli as well as the subjects own voice resulted in HG power changes in superior temporal lobe and Wernickes area. In summary, this study represents a comprehensive characterization of overt and covert speech using electrophysiological imaging with high spatial and temporal resolution. It thereby complements the findings of previous neuroimaging studies of language and thus further adds to current understanding of word processing in humans.
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Electrocorticographic frequency alteration mapping for extraoperative localization of speech cortex.
Neurosurgery
PUBLISHED: 01-21-2010
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Electrocortical stimulation (ECS) has long been established for delineating eloquent cortex in extraoperative mapping. However, ECS is still coarse and inefficient in delineating regions of functional cortex and can be hampered by afterdischarges. Given these constraints, an adjunct approach to defining motor cortex is the use of electrocorticographic (ECoG) signal changes associated with active regions of cortex. The broad range of frequency oscillations are categorized into 2 main groups with respect to sensorimotor cortex: low-frequency bands (LFBs) and high-frequency bands (HFBs). The LFBs tend to show a power reduction, whereas the HFBs show power increases with cortical activation. These power changes associated with activated cortex could potentially provide a powerful tool in delineating areas of speech cortex. We explore ECoG signal alterations as they occur with activated region of speech cortex and its potential in clinical brain mapping applications.
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Passive real-time identification of speech and motor cortex during an awake craniotomy.
Epilepsy Behav
PUBLISHED: 01-08-2010
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Precise localization of eloquent cortex is a clinical necessity prior to surgical resections adjacent to speech or motor cortex. In the intraoperative setting, this traditionally requires inducing temporary lesions by direct electrocortical stimulation (DECS). In an attempt to increase efficiency and potentially reduce the amount of necessary stimulation, we used a passive mapping procedure in the setting of an awake craniotomy for tumor in two patients resection. We recorded electrocorticographic (ECoG) signals from exposed cortex while patients performed simple cue-directed motor and speech tasks. SIGFRIED, a procedure for real-time event detection, was used to identify areas of cortical activation by detecting task-related modulations in the ECoG high gamma band. SIGFRIEDs real-time output quickly localized motor and speech areas of cortex similar to those identified by DECS. In conclusion, real-time passive identification of cortical function using SIGFRIED may serve as a useful adjunct to cortical stimulation mapping in the intraoperative setting.
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Ipsilateral directional encoding of joystick movements in human cortex.
Conf Proc IEEE Eng Med Biol Soc
PUBLISHED: 12-08-2009
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The majority of Brain Computer Interfaces have relied on signals related to primary motor cortex and the operation of the contralateral limb. Recently, the physiology associated with same-sided (ipsilateral) motor movements has been found to have a unique cortical physiology. This study sets out to assess whether more complex motor movements can be discerned utilizing ipsilateral cortical signals. In this study, three invasively monitored human subjects were recorded while performing a center out joystick task with the hand ipsilateral to the hemispheric subdural grid array. It was found that directional tuning was present in ipsilateral cortex. This information was encoded in both distinct anatomic populations and spectral distributions. These findings support the notion that ipsilateral signals may provide added information for BCI operation in the future.
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Evolution of brain-computer interfaces: going beyond classic motor physiology.
Neurosurg Focus
PUBLISHED: 07-03-2009
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The notion that a computer can decode brain signals to infer the intentions of a human and then enact those intentions directly through a machine is becoming a realistic technical possibility. These types of devices are known as brain-computer interfaces (BCIs). The evolution of these neuroprosthetic technologies could have significant implications for patients with motor disabilities by enhancing their ability to interact and communicate with their environment. The cortical physiology most investigated and used for device control has been brain signals from the primary motor cortex. To date, this classic motor physiology has been an effective substrate for demonstrating the potential efficacy of BCI-based control. However, emerging research now stands to further enhance our understanding of the cortical physiology underpinning human intent and provide further signals for more complex brain-derived control. In this review, the authors report the current status of BCIs and detail the emerging research trends that stand to augment clinical applications in the future.
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Microscale recording from human motor cortex: implications for minimally invasive electrocorticographic brain-computer interfaces.
Neurosurg Focus
PUBLISHED: 07-03-2009
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There is a growing interest in the use of recording from the surface of the brain, known as electrocorticography (ECoG), as a practical signal platform for brain-computer interface application. The signal has a combination of high signal quality and long-term stability that may be the ideal intermediate modality for future application. The research paradigm for studying ECoG signals uses patients requiring invasive monitoring for seizure localization. The implanted arrays span cortex areas on the order of centimeters. Currently, it is unknown what level of motor information can be discerned from small regions of human cortex with microscale ECoG recording.
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An offline evaluation of the autoregressive spectrum for electrocorticography.
IEEE Trans Biomed Eng
PUBLISHED: 04-25-2009
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Electrical signals acquired from the cortical surface, or electrocorticography (ECoG), exhibit high spatial and temporal resolution and are valuable for mapping brain activity, detecting irregularities, and controlling a brain-computer interface. As with scalp-recorded EEG, much of the identified information content in ECoG is manifested as amplitude modulations of specific frequency bands. Autoregressive (AR) spectral estimation has proven successful for modeling the well-defined and comparatively limited EEG spectrum. However, because the ECoG spectrum is significantly more extensive with yet undefined dynamics, it cannot be assumed that the ECoG spectrum can be accurately estimated using the same AR model parameters that are valid for analogous EEG studies. This study provides an offline evaluation of AR modeling of ECoG signals for detecting tongue movements. The resulting model parameters can serve as a reference for related AR spectral analysis of ECoG signals.
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A practical procedure for real-time functional mapping of eloquent cortex using electrocorticographic signals in humans.
Epilepsy Behav
PUBLISHED: 02-13-2009
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Functional mapping of eloquent cortex is often necessary prior to invasive brain surgery, but current techniques that derive this mapping have important limitations. In this article, we demonstrate the first comprehensive evaluation of a rapid, robust, and practical mapping system that uses passive recordings of electrocorticographic signals. This mapping procedure is based on the BCI2000 and SIGFRIED technologies that we have been developing over the past several years. In our study, we evaluated 10 patients with epilepsy from four different institutions and compared the results of our procedure with the results derived using electrical cortical stimulation (ECS) mapping. The results show that our procedure derives a functional motor cortical map in only a few minutes. They also show a substantial concurrence with the results derived using ECS mapping. Specifically, compared with ECS maps, a next-neighbor evaluation showed no false negatives, and only 0.46 and 1.10% false positives for hand and tongue maps, respectively. In summary, we demonstrate the first comprehensive evaluation of a practical and robust mapping procedure that could become a new tool for planning of invasive brain surgeries.
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Resting-state spontaneous fluctuations in brain activity: a new paradigm for presurgical planning using fMRI.
Acad Radiol
PUBLISHED: 01-30-2009
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Task-evoked functional MRI (fMRI) has been used successfully in the study of brain function and clinically for presurgical localization of eloquent brain regions prior to the performance of brain surgery. This method requires patient cooperation and is not useful in young children or if the patient has cognitive dysfunction or physical impairment. An alternative method that can overcome some of these disadvantages measures the intrinsic function of the brain using resting-state fMRI. This method does not require any task performance and measures the spontaneous low-frequency (<0.1 Hz) fluctuations of the fMRI signal over time. Our objective in the present work is to provide preliminary information on the possible clinical utility of this technique for presurgical planning and on possible future applications.
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IpsiHand Bravo: an improved EEG-based brain-computer interface for hand motor control rehabilitation.
Conf Proc IEEE Eng Med Biol Soc
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Stroke and other nervous system injuries can damage or destroy hand motor control and greatly upset daily activities. Brain computer interfaces (BCIs) represent an emerging technology that can bypass damaged nerves to restore basic motor function and provide more effective rehabilitation. A wireless BCI system was implemented to realize these goals using electroencephalographic brain signals, machine learning techniques, and a custom designed orthosis. The IpsiHand Bravo BCI system is designed to reach a large demographic by using non-traditional brain signals and improving on past BCI system pitfalls.
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Proceedings of the Third International Workshop on Advances in Electrocorticography.
Epilepsy Behav
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The Third International Workshop on Advances in Electrocorticography (ECoG) was convened in Washington, DC, on November 10-11, 2011. As in prior meetings, a true multidisciplinary fusion of clinicians, scientists, and engineers from many disciplines gathered to summarize contemporary experiences in brain surface recordings. The proceedings of this meeting serve as evidence of a very robust and transformative field but will yet again require revision to incorporate the advances that the following year will surely bring.
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The baric probe: a novel long-term implantable intracranial pressure monitor with ultrasound-based interrogation.
J Neurosurg Pediatr
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Prompt diagnosis of shunt malfunction is critical in preventing neurological morbidity and death in individuals with hydrocephalus; however, diagnostic methods for this condition remain limited. For several decades, investigators have sought a long-term, implantable intracranial pressure (ICP) monitor to assist in the diagnosis of shunt malfunction, but efforts have been impeded by device complexity, marked measurement drift, and limited instrumentation lifespan. In the current report, the authors introduce an entirely novel, simple, compressible gas design that addresses each of these problems.
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Electrocorticographic (ECoG) correlates of human arm movements.
Exp Brain Res
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Invasive and non-invasive brain-computer interface (BCI) studies have long focused on the motor cortex for kinematic control of artificial devices. Most of these studies have used single-neuron recordings or electroencephalography (EEG). Electrocorticography (ECoG) is a relatively new recording modality in BCI research that has primarily been built on successes in EEG recordings. We built on prior experiments related to single-neuron recording and quantitatively compare the extent to which different brain regions reflect kinematic tuning parameters of hand speed, direction, and velocity in both a reaching and tracing task in humans. Hand and arm movement experiments using ECoG have shown positive results before, but the tasks were not designed to tease out which kinematics are encoded. In non-human primates, the relationships among these kinematics have been more carefully documented, and we sought to begin elucidating that relationship in humans using ECoG. The largest modulation in ECoG activity for direction, speed, and velocity representation was found in the primary motor cortex. We also found consistent cosine tuning across both tasks, to hand direction and velocity in the high gamma band (70-160 Hz). Thus, the results of this study clarify the neural substrates involved in encoding aspects of motor preparation and execution and confirm the important role of the motor cortex in BCI applications.
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Clustering of resting state networks.
PLoS ONE
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The goal of the study was to demonstrate a hierarchical structure of resting state activity in the healthy brain using a data-driven clustering algorithm.
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Using ipsilateral motor signals in the unaffected cerebral hemisphere as a signal platform for brain-computer interfaces in hemiplegic stroke survivors.
J Neural Eng
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Brain-computer interface (BCI) systems have emerged as a method to restore function and enhance communication in motor impaired patients. To date, this has been applied primarily to patients who have a compromised motor outflow due to spinal cord dysfunction, but an intact and functioning cerebral cortex. The cortical physiology associated with movement of the contralateral limb has typically been the signal substrate that has been used as a control signal. While this is an ideal control platform in patients with an intact motor cortex, these signals are lost after a hemispheric stroke. Thus, a different control signal is needed that could provide control capability for a patient with a hemiparetic limb. Previous studies have shown that there is a distinct cortical physiology associated with ipsilateral, or same-sided, limb movements. Thus far, it was unknown whether stroke survivors could intentionally and effectively modulate this ipsilateral motor activity from their unaffected hemisphere. Therefore, this study seeks to evaluate whether stroke survivors could effectively utilize ipsilateral motor activity from their unaffected hemisphere to achieve this BCI control. To investigate this possibility, electroencephalographic (EEG) signals were recorded from four chronic hemispheric stroke patients as they performed (or attempted to perform) real and imagined hand tasks using either their affected or unaffected hand. Following performance of the screening task, the ability of patients to utilize a BCI system was investigated during on-line control of a one-dimensional control task. Significant ipsilateral motor signals (associated with movement intentions of the affected hand) in the unaffected hemisphere, which were found to be distinct from rest and contralateral signals, were identified and subsequently used for a simple online BCI control task. We demonstrate here for the first time that EEG signals from the unaffected hemisphere, associated with overt and imagined movements of the affected hand, can enable stroke survivors to control a one-dimensional computer cursor rapidly and accurately. This ipsilateral motor activity enabled users to achieve final target accuracies between 68% and 91% within 15 min. These findings suggest that ipsilateral motor activity from the unaffected hemisphere in stroke survivors could provide a physiological substrate for BCI operation that can be further developed as a long-term assistive device or potentially provide a novel tool for rehabilitation.
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Temporal evolution of gamma activity in human cortex during an overt and covert word repetition task.
Front Hum Neurosci
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Several scientists have proposed different models for cortical processing of speech. Classically, the regions participating in language were thought to be modular with a linear sequence of activations. More recently, modern theoretical models have posited a more hierarchical and distributed interaction of anatomic areas for the various stages of speech processing. Traditional imaging techniques can only define the location or time of cortical activation, which impedes the further evaluation and refinement of these models. In this study, we take advantage of recordings from the surface of the brain [electrocorticography (ECoG)], which can accurately detect the location and timing of cortical activations, to study the time course of ECoG high gamma (HG) modulations during an overt and covert word repetition task for different cortical areas. For overt word production, our results show substantial perisylvian cortical activations early in the perceptual phase of the task that were maintained through word articulation. However, this broad activation is attenuated during the expressive phase of covert word repetition. Across the different repetition tasks, the utilization of the different cortical sites within the perisylvian region varied in the degree of activation dependent on which stimulus was provided (auditory or visual cue) and whether the word was to be spoken or imagined. Taken together, the data support current models of speech that have been previously described with functional imaging. Moreover, this study demonstrates that the broad perisylvian speech network activates early and maintains suprathreshold activation throughout the word repetition task that appears to be modulated by the demands of different conditions.
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Mapping sensorimotor cortex with slow cortical potential resting-state networks while awake and under anesthesia.
Neurosurgery
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The emerging insight into resting-state cortical networks has been important in our understanding of the fundamental architecture of brain organization. These networks, which were originally identified with functional magnetic resonance imaging, are also seen in the correlation topography of the infraslow rhythms of local field potentials. Because of the fundamental nature of these networks and their independence from task-related activations, we posit that, in addition to their neuroscientific relevance, these slow cortical potential networks could play an important role in clinical brain mapping.
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Decoding covert spatial attention using electrocorticographic (ECoG) signals in humans.
Neuroimage
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This study shows that electrocorticographic (ECoG) signals recorded from the surface of the brain provide detailed information about shifting of visual attention and its directional orientation in humans. ECoG allows for the identification of the cortical areas and time periods that hold the most information about covert attentional shifts. Our results suggest a transient distributed fronto-parietal mechanism for orienting of attention that is represented by different physiological processes. This neural mechanism encodes not only whether or not a subject shifts their attention to a location, but also the locus of attention. This work contributes to our understanding of the electrophysiological representation of attention in humans. It may also eventually lead to brain-computer interfaces (BCIs) that optimize user interaction with their surroundings or that allow people to communicate choices simply by shifting attention to them.
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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.

How does it work?

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.