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Electrocorticography

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https://www.readbyqxmd.com/read/27926827/decoding-hand-gestures-from-primary-somatosensory-cortex-using-high-density-ecog
#1
Mariana P Branco, Zachary V Freudenburg, Erik J Aarnoutse, Martin G Bleichner, Mariska J Vansteensel, Nick F Ramsey
Electrocorticography (ECoG) based Brain-Computer Interfaces (BCIs) have been proposed as a way to restore and replace motor function or communication in severely paralyzed people. To date, most motor-based BCIs have either focused on the sensorimotor cortex as a whole or on the primary motor cortex (M1) as a source of signals for this purpose. Still, target areas for BCI are not confined to M1, and more brain regions may provide suitable BCI control signals. A logical candidate is the primary somatosensory cortex (S1), which not only shares similar somatotopic organization to M1, but also has been suggested to have a role beyond sensory feedback during movement execution...
December 4, 2016: NeuroImage
https://www.readbyqxmd.com/read/27912169/non-harmonicity-in-high-frequency-components-of-the-intra-operative-corticogram-to-delineate-epileptogenic-tissue-during-surgery
#2
Evelien E Geertsema, Maryse A van 't Klooster, Nicole E C van Klink, Frans S S Leijten, Peter C van Rijen, Gerhard H Visser, Stiliyan N Kalitzin, Maeike Zijlmans
OBJECTIVE: We aimed to test the potential of auto-regressive model residual modulation (ARRm), an artefact-insensitive method based on non-harmonicity of the high-frequency signal, to identify epileptogenic tissue during surgery. METHODS: Intra-operative electrocorticography (ECoG) of 54 patients with refractory focal epilepsy were recorded pre- and post-resection at 2048Hz. The ARRm was calculated in one-minute epochs in which high-frequency oscillations (HFOs; fast ripples, 250-500Hz; ripples, 80-250Hz) and spikes were marked...
November 17, 2016: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/27912111/can-ictal-meg-obviate-the-need-for-phase-ii-monitoring-in-people-with-drug-refractory-epilepsy-a-prospective-observational-study
#3
Bhargavi Ramanujam, Kamal Bharti, Vibhin Viswanathan, Ajay Garg, Madhavi Tripathi, Chandrashekhar Bal, P Sarat Chandra, Manjari Tripathi
PURPOSE: To determine if ictal-magnetoencephalography (ictal-MEG) source localization (SL) added information towards delineating the ictal-onset zone (IOZ), whether and how it helped final decision-making in epilepsy-surgery. METHODS: Definite focal clusters on ictal-MEG were available for 32 DRE-patients, data was analyzed (single equivalent current dipole (ECD) model), SL done. Clinical history, long-term video-EEG (VEEG) monitoring, epilepsy-protocol MRI, FDG-PET, ictal-SPECT and interictal-MEG were discussed at the multispeciality Epilepsy Surgery Case-conference (ESC)...
October 31, 2016: Seizure: the Journal of the British Epilepsy Association
https://www.readbyqxmd.com/read/27900947/continuous-decoding-of-human-grasp-kinematics-using-epidural-and-subdural-signals
#4
Robert D Flint, Joshua M Rosenow, Matthew C Tate, Marc W Slutzky
OBJECTIVE: Restoring or replacing function in paralyzed individuals will one day be achieved through the use of brain-machine interfaces. Regaining hand function is a major goal for paralyzed patients. Two competing prerequisites for the widespread adoption of any hand neuroprosthesis are accurate control over the fine details of movement, and minimized invasiveness. Here, we explore the interplay between these two goals by comparing our ability to decode hand movements with subdural and epidural field potentials (EFPs)...
November 30, 2016: Journal of Neural Engineering
https://www.readbyqxmd.com/read/27875590/spatio-temporal-progression-of-cortical-activity-related-to-continuous-overt-and-covert-speech-production-in-a-reading-task
#5
Jonathan S Brumberg, Dean J Krusienski, Shreya Chakrabarti, Aysegul Gunduz, Peter Brunner, Anthony L Ritaccio, Gerwin Schalk
How the human brain plans, executes, and monitors continuous and fluent speech has remained largely elusive. For example, previous research has defined the cortical locations most important for different aspects of speech function, but has not yet yielded a definition of the temporal progression of involvement of those locations as speech progresses either overtly or covertly. In this paper, we uncovered the spatio-temporal evolution of neuronal population-level activity related to continuous overt speech, and identified those locations that shared activity characteristics across overt and covert speech...
2016: PloS One
https://www.readbyqxmd.com/read/27862478/reductions-in-cortical-alpha-activity-enhancements-in-neural-responses-and-impaired-gap-detection-caused-by-sodium-salicylate-in-awake-guinea-pigs
#6
Joel I Berger, Ben Coomber, Mark N Wallace, Alan R Palmer
Tinnitus chronically affects between 10-15% of the population but despite its prevalence, the underlying mechanisms are still not properly understood. One experimental model involves administration of high doses of sodium salicylate, as this is known to reliably induce tinnitus in both humans and animals. Guinea pigs were implanted with chronic electrocorticography (ECoG) electrode arrays, with silver ball electrodes placed on the dura over left and right auditory cortex. Two more electrodes were positioned over the cerebellum to monitor auditory brainstem responses (ABRs)...
November 12, 2016: European Journal of Neuroscience
https://www.readbyqxmd.com/read/27858575/chronic-electrocorticography-for-sensing-movement-intention-and-closed-loop-deep-brain-stimulation-with-wearable-sensors-in-an-essential-tremor-patient
#7
Jeffrey A Herron, Margaret C Thompson, Timothy Brown, Howard J Chizeck, Jeffrey G Ojemann, Andrew L Ko
Deep brain stimulation (DBS) has become a widespread and valuable treatment for patients with movement disorders such as essential tremor (ET). However, current DBS treatment constantly delivers stimulation in an open loop, which can be inefficient. Closing the loop with sensors to provide feedback may increase power efficiency and reduce side effects for patients. New implantable neuromodulation platforms, such as the Medtronic Activa PC+S DBS system, offer important data sources by providing chronic neural sensing capabilities and a means of investigating dynamic stimulation based on symptom measurements...
November 18, 2016: Journal of Neurosurgery
https://www.readbyqxmd.com/read/27834621/repeat-surgery-for-focal-cortical-dysplasias-in-children-indications-and-outcomes
#8
Matthew F Sacino, Cheng-Ying Ho, Matthew T Whitehead, Amy Kao, Dewi Depositario-Cabacar, John S Myseros, Suresh N Magge, Robert F Keating, William D Gaillard, Chima O Oluigbo
OBJECTIVE Focal cortical dysplasia (FCD) is a common cause of medically intractable epilepsy that often may be treated by surgery. Following resection, many patients continue to experience seizures, necessitating a decision for further surgery to achieve the desired seizure outcomes. Few studies exist on the efficacy of reoperation for intractable epilepsy due to FCD in pediatric cohorts, including the definition of prognostic factors correlated with clinical benefit from further resection. METHODS The authors retrospectively analyzed the medical records and MR images of 22 consecutive pediatric patients who underwent repeat FCD resection after unsuccessful first surgery at the Children's National Health System between March 2005 and April 2015...
November 11, 2016: Journal of Neurosurgery. Pediatrics
https://www.readbyqxmd.com/read/27821758/mapping-human-temporal-and-parietal-neuronal-population-activity-and-functional-coupling-during-mathematical-cognition
#9
Amy L Daitch, Brett L Foster, Jessica Schrouff, Vinitha Rangarajan, Itır Kaşikçi, Sandra Gattas, Josef Parvizi
Brain areas within the lateral parietal cortex (LPC) and ventral temporal cortex (VTC) have been shown to code for abstract quantity representations and for symbolic numerical representations, respectively. To explore the fast dynamics of activity within each region and the interaction between them, we used electrocorticography recordings from 16 neurosurgical subjects implanted with grids of electrodes over these two regions and tracked the activity within and between the regions as subjects performed three different numerical tasks...
November 15, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27812318/neural-correlates-of-auditory-perceptual-awareness-and-release-from-informational-masking-recorded-directly-from-human-cortex-a-case-study
#10
Andrew R Dykstra, Eric Halgren, Alexander Gutschalk, Emad N Eskandar, Sydney S Cash
In complex acoustic environments, even salient supra-threshold sounds sometimes go unperceived, a phenomenon known as informational masking. The neural basis of informational masking (and its release) has not been well-characterized, particularly outside auditory cortex. We combined electrocorticography in a neurosurgical patient undergoing invasive epilepsy monitoring with trial-by-trial perceptual reports of isochronous target-tone streams embedded in random multi-tone maskers. Awareness of such masker-embedded target streams was associated with a focal negativity between 100 and 200 ms and high-gamma activity (HGA) between 50 and 250 ms (both in auditory cortex on the posterolateral superior temporal gyrus) as well as a broad P3b-like potential (between ~300 and 600 ms) with generators in ventrolateral frontal and lateral temporal cortex...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27791089/human-cortical-hippocampal-dialogue-in-wake-and-slow-wave-sleep
#11
Anish Mitra, Abraham Z Snyder, Carl D Hacker, Mrinal Pahwa, Enzo Tagliazucchi, Helmut Laufs, Eric C Leuthardt, Marcus E Raichle
Declarative memory consolidation is hypothesized to require a two-stage, reciprocal cortical-hippocampal dialogue. According to this model, higher frequency signals convey information from the cortex to hippocampus during wakefulness, but in the reverse direction during slow-wave sleep (SWS). Conversely, lower-frequency activity propagates from the information "receiver" to the "sender" to coordinate the timing of information transfer. Reversal of sender/receiver roles across wake and SWS implies that higher- and lower-frequency signaling should reverse direction between the cortex and hippocampus...
November 1, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27780085/proceedings-of-the-eighth-international-workshop-on-advances-in-electrocorticography
#12
Anthony L Ritaccio, Justin Williams, Tim Denison, Brett L Foster, Philip A Starr, Aysegul Gunduz, Maeike Zijlmans, Gerwin Schalk
Excerpted proceedings of the Eighth International Workshop on Advances in Electrocorticography (ECoG), which convened October 15-16, 2015 in Chicago, IL, are presented. The workshop series has become the foremost gathering to present current basic and clinical research in subdural brain signal recording and analysis.
October 22, 2016: Epilepsy & Behavior: E&B
https://www.readbyqxmd.com/read/27729844/automatic-speech-recognition-from-neural-signals-a-focused-review
#13
Christian Herff, Tanja Schultz
Speech interfaces have become widely accepted and are nowadays integrated in various real-life applications and devices. They have become a part of our daily life. However, speech interfaces presume the ability to produce intelligible speech, which might be impossible due to either loud environments, bothering bystanders or incapabilities to produce speech (i.e., patients suffering from locked-in syndrome). For these reasons it would be highly desirable to not speak but to simply envision oneself to say words or sentences...
2016: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/27721161/prospective-and-live-fast-ripple-detection-and-localization-in-the-operating-room-impact-on-epilepsy-surgery-outcomes-in-children
#14
Shaun A Hussain, Gary W Mathern, Raman Sankar, Joyce Y Wu
OBJECTIVE: Fast ripples (FR, 250-500Hz) are proposed biomarkers of the epileptogenic zone on the basis of several retrospective reports linking postoperative seizure freedom to their complete resection. There are no clinical trials or prospective reports validating the use of FR as characterized by electrocorticography (ECoG), to guide the scope of epilepsy surgery, and to inform prognosis thereafter. We set out to prospectively evaluate the utility of FR resection to predict postoperative epilepsy outcomes, and examine the feasibility of "live" intraoperative FR ascertainment...
September 23, 2016: Epilepsy Research
https://www.readbyqxmd.com/read/27712455/independent-component-decomposition-of-human-somatosensory-evoked-potentials-recorded-by-micro-electrocorticography
#15
Irene Rembado, Elisa Castagnola, Luca Turella, Tamara Ius, Riccardo Budai, Alberto Ansaldo, Gian Nicola Angotzi, Francesco Debertoldi, Davide Ricci, Miran Skrap, Luciano Fadiga
High-density surface microelectrodes for electrocorticography (ECoG) have become more common in recent years for recording electrical signals from the cortex. With an acceptable invasiveness/signal fidelity trade-off and high spatial resolution, micro-ECoG is a promising tool to resolve fine task-related spatial-temporal dynamics. However, volume conduction - not a negligible phenomenon - is likely to frustrate efforts to obtain reliable and resolved signals from a sub-millimeter electrode array. To address this issue, we performed an independent component analysis (ICA) on micro-ECoG recordings of somatosensory-evoked potentials (SEPs) elicited by median nerve stimulation in three human patients undergoing brain surgery for tumor resection...
August 18, 2016: International Journal of Neural Systems
https://www.readbyqxmd.com/read/27703809/hippocampography-guides-consistent-mesial-resections-in-neocortical-temporal-lobe-epilepsy
#16
Marcus C Ng, Ronan Kilbride, Mirela Simon, Emad Eskandar, Andrew J Cole
Background. The optimal surgery in lesional neocortical temporal lobe epilepsy is unknown. Hippocampal electrocorticography maximizes seizure freedom by identifying normal-appearing epileptogenic tissue for resection and minimizes neuropsychological deficit by limiting resection to demonstrably epileptogenic tissue. We examined whether standardized hippocampal electrocorticography (hippocampography) guides resection for more consistent hippocampectomy than unguided resection in conventional electrocorticography focused on the lesion...
2016: Epilepsy Research and Treatment
https://www.readbyqxmd.com/read/27695546/ganglioglioma-single-institutional-experience-of-24-cases-with-review-of-literature
#17
Vivek Tandon, Sumit Bansal, P Sarat Chandra, Ashish Suri, Manjari Tripathi, Mehar C Sharma, Avijit Sarkari, Ashok K Mahapatra
BACKGROUND: Ganglioglioma is a common seizure associated tumor. The goal of this study was to observe the postoperative outcome in patients with gangliogliomas. MATERIAL AND METHODS: A total 24 patients with gangliogliomas who underwent surgery at our institute from 2008 to 2011 were included. There were 13 males (54%) in our study. A retrospective analysis for the demographic profile, surgery and outcome was performed using STATA software. Literature on this subject was also reviewed, MEDLINE and PUBMED databases were searched...
October 2016: Asian Journal of Neurosurgery
https://www.readbyqxmd.com/read/27686506/clinical-impact-and-implication-of-real-time-oscillation-analysis-for-language-mapping
#18
Ogawa H, Kamada K, Kapeller C, Pruckle R, Takeuchi F, Hiroshima S, Anei R, Guger G
BACKGROUND: We developed a functional brain analysis system that enabled us to perform real-time task-related electrocorticography (ECoG) and evaluated its potential in clinical practice. We hypothesized that high gamma activity (HGA) mapping would provide better spatial and temporal resolution with high signal-to-noise ratios. METHODS: Seven awake craniotomy patients were evaluated. ECoG was recorded during language tasks using subdural grids, and HGA (60-170 Hz) maps were obtained in real time...
September 26, 2016: World Neurosurgery
https://www.readbyqxmd.com/read/27677673/large-field-of-view-movement-compensated-intrinsic-optical-signal-imaging-for-the-characterization-of-the-haemodynamic-response-to-spreading-depolarizations-in-large-gyrencephalic-brains
#19
Michael Johannes Schöll, Edgar Santos, Renan Sanchez-Porras, Modar Kentar, Markus Gramer, Humberto Silos, Zelong Zheng, Yuan Gang, Anthony John Strong, Rudolf Graf, Andreas Unterberg, Oliver W Sakowitz, Hartmut Dickhaus
Haemodynamic responses to spreading depolarizations (SDs) have an important role during the development of secondary brain damage. Characterization of the haemodynamic responses in larger brains, however, is difficult due to movement artefacts. Intrinsic optical signal (IOS) imaging, laser speckle flowmetry (LSF) and electrocorticography were performed in different configurations in three groups of in total 18 swine. SDs were elicited by topical application of KCl or occurred spontaneously after middle cerebral artery occlusion...
September 27, 2016: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/27677490/diagnostic-utility-of-invasive-eeg-for-epilepsy-surgery-indications-modalities-and-techniques
#20
Prasanna Jayakar, Jean Gotman, A Simon Harvey, André Palmini, Laura Tassi, Donald Schomer, Francois Dubeau, Fabrice Bartolomei, Alice Yu, Pavel Kršek, Demetrios Velis, Philippe Kahane
Many patients with medically refractory epilepsy now undergo successful surgery based on noninvasive diagnostic information, but intracranial electroencephalography (IEEG) continues to be used as increasingly complex cases are considered surgical candidates. The indications for IEEG and the modalities employed vary across epilepsy surgical centers; each modality has its advantages and limitations. IEEG can be performed in the same intraoperative setting, that is, intraoperative electrocorticography, or through an independent implantation procedure with chronic extraoperative recordings; the latter are not only resource intensive but also carry risk...
November 2016: Epilepsia
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