DOCSLIB.ORG

Regional Abnormality of Functional Connectivity Is Associated with Clinical Manifestations in Individuals with Intractable Focal

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Regional Abnormality of Functional Connectivity Is Associated with Clinical Manifestations in Individuals with Intractable Focal www.nature.com/scientificreports OPEN Regional abnormality of functional connectivity is associated with clinical manifestations in individuals with intractable focal epilepsy Yasuo Nakai1*, Hiroki Nishibayashi1, Tomohiro Donishi2, Masaki Terada3, Naoyuki Nakao1 & Yoshiki Kaneoke2 We explored regional functional connectivity alterations in intractable focal epilepsy brains using resting-state functional MRI. Distributions of the network parameters (corresponding to degree and eigenvector centrality) measured at each brain region for all 25 patients were signifcantly diferent from age- and sex-matched control data that were estimated by a healthy control dataset (n = 582, 18–84 years old). The number of abnormal regions whose parameters exceeded the mean + 2 SD of age- and sex-matched data for each patient were associated with various clinical parameters such as the duration of illness and seizure severity. Furthermore, abnormal regions for each patient tended to have functional connections with each other (mean ± SD = 58.6 ± 20.2%), the magnitude of which was negatively related to the quality of life. The abnormal regions distributed within the default mode network with signifcantly higher probability (p < 0.05) in 7 of 25 patients. We consider that the detection of abnormal regions by functional connectivity analysis using a large number of control datasets is useful for the numerical assessment of each patient’s clinical conditions, although further study is necessary to elucidate etiology-specifc abnormalities. Approximately 25% of epilepsy patients are medically intractable 1. For these patients, various types of brain surgeries have been performed to improve their quality of life (QOL) by reducing seizure frequency2. However, long-term outcomes, such as the seizure freedom rate, have been stagnating, and treatment of intractable focal epilepsy is still challenging 3. Previous studies showed that even for temporal lobe epilepsy (TLE) with mesial tem- poral lobe sclerosis, the seizure freedom rate was 53–84% afer anteromesial temporal lobe resections. Similarly, the seizure freedom rate for patients with localized neocortical epilepsy was 36–76%4. Tese data suggest that the epileptogenic zone extends outsize the local brain lesions for some patients, and these epileptogenic zones could not be detected by conventional methodologies such as scalp or intracranial electroencephalography (EEG), structural magnetic resonance imaging (MRI), magnetoencephalography, and positron emission tomography. It is ofen assumed that the epileptogenic zone extends by way of the brain network; for example, mirror focus arises in the contralateral hemisphere in temporal lobe epilepsy in its clinical course 5. Te epileptogenic zone extends to the whole brain and the efect of brain surgery worsen over time6. Recently, resting-state functional MRI (rs-fMRI) studies have been used to elucidate normal and various abnormal brain functional networks7–9 and many studies have shown that epilepsy patients have abnormal brain networks as measured by rs-fMRI10–13. However, the majority of studies performed group analyses that did not focus on individual epilepsy network alterations. If each individual brain network could be assessed before surgery, a better surgical outcome might be achieved. We consider that focal epilepsy has a common pathophysiological brain functional abnormality even if its epileptic focus is varied. Corresponding to this idea, some anti-epileptic drugs such as carbamazepine are efective for focal epilepsy but not for generalized epilepsy 14. Tus, we investigated whether brain network abnormalities could be assessed in individuals with various types 1Department of Neurological Surgery, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan. 2Department of System Neurophysiology, Wakayama Medical University, 811-1 Kimiidera, Wakayama 641-8509, Japan. 3Wakayama-Minami Radiology Clinic, 870-2 Kimiidera, Wakayama 641-0012, Japan. *email: [email protected] Scientifc Reports | (2021) 11:1545 | https://doi.org/10.1038/s41598-021-81207-6 1 Vol.:(0123456789) www.nature.com/scientificreports/ of intractable focal epilepsies by comparing a large number of brain network data from healthy controls. Brain network structure could vary with various causes such as age15,16, sex17, and intelligence18,19, so a large amount of control data is necessary to determine the normal range and to assess each individual brain network structure. Centrality analysis using rs-fMRI has detected alterations in the network in several epilepsy types 10,20,21, and initial observations suggested a network disruption in epilepsy and disease progression as well as postsurgical seizure outcome, which emphasizes that graph theoretical analysis may lend markers for disease staging and prognostics. In this present study, we employed normalized α-centrality (nAC) on rs-fMRI22,23 to quantify the brain regional network organization to compare diferent centralities. Te nAC measures the strength of a node in a network from the local viewpoint to the global viewpoint by changing the parameter (that is, α) from zero to 1/λ; thereby, λ is the maximum eigenvalue of the adjacency matrix of the network. We calculated nAC val- ues at each brain region with two diferent α values (0 and 1/λ) to determine the regional abnormality. Locally connected nodes were refected by nAC at α = 0 (nAC0), which corresponds to degree centrality. Conversely, globally connected nodes were refected by nAC at α = 1/λ (nAC1), which correspond to eigenvector centrality. nAC0 refects how many regions are connected to a given region, whereas a large nAC1 refects how strongly the connectivity of a given region contributes to the whole network. Te aim of this study was to elucidate abnormal brain regions using network properties that are specifc to each individual with intractable focal epilepsy by comparison with a relatively large number of control data. If it was possible, we assessed the relationship between these regional abnormalities and clinical parameters such as the QOL or seizure severity of patients. Results Patient characteristics. Twenty-fve patients with intractable (or drug-resistant) focal epilepsy (9 females and 16 males, age ranged from 16 to 70 years old, mean ± SD: 39.1 ± 12.3 years) participated in this study. Te duration of illness ranged from 1 to 42 years with a mean of 19.8 years; the number of antiepileptic drugs ranged from 1 to 4 with a mean of 2.8. Tree patients (cases 1, 12, and 13) underwent epilepsy surgery monitoring with electrocorticography (ECoG) afer the MRI study. Twelve patients (cases 1–12) had structural lesions (5 cortical malformations, 3 tumourous lesions, 2 hippocampal atrophy, 1 amygdala lesion, and 1 hippocampal lesion). Te demographic data for the patients including age at rs-fMRI, sex, epilepsy onset, duration of epilepsy, etiology, seizure type, EEG, and MRI fndings are summarized in Supplementary Table S1. We divided the patients into three groups based on the clinical data as follows: lobar type of temporal lobe (TLE type, n = 10), lobar type of extra-temporal lobe (focal type, n = 5), and multilobar type (n = 10)24. Network characteristics. Te number of nodes was 388 because the cerebral gray matters were divided into 368 regions using Atlas of Intrinsic Connectivity of Homotopic Areas (AICHA)25 and the cerebellar gray matters were divided into 20 regions using Automated Anatomical Labeling atlas (AAL)26 for 20 regions in the cerebellum (Supplementary Table S2). However, the number of edges varied with individuals as the func- tional connectivity strength measured by Pearson’s correlation coefcient between two regions was binarized at Z > 1.96 to make an adjacency matrix for each subject (see “Materials and methods”). Te mean number of edges was 6224 ± 1180 for the patients and 6845 ± 1201 for the controls. Te analysis of covariance revealed that the number of edges was signifcantly diferent between the controls and the epilepsy patients with age as a nui- sance covariate (df = 1, F = 7.19, p = 0.0075) and there was a signifcant interaction between group and age (df = 1, F = 6.97, p = 0.0085) (Supplementary Fig. S1). Te number of edges was not related to the clinical parameters of the patients, such as duration of illness (p > 0.05, Spearman’s partial correlation analysis excluding the efect of age), the number of anti-epileptic drugs (AEDs), the Quality of Life in the Epilepsy Inventory (QOLIE-31) and Liverpool Seizure Severity Scale (LSSS) (p > 0.05, Spearman’s correlation analysis). Distributions of nAC0 and nAC1. Te frequency distributions of the nAC values for each subject are cal- culated, and the representative data are shown in Fig. 1 (all the data are shown in Supplementary Figs. S2, S3). We found that the number of regions with lower nAC values (< 0.2) and higher nAC values (> 0.5) were larger than those for the controls for all the patients. Chi-square tests revealed that distributions of nAC0 and nAC1 for each patient were signifcantly diference from those for age- and sex-matched controls (p < 0.005). Spatial distributions of these values for the healthy controls (mean values for the 20, 40, and 60 years old) are shown in Supplementary Fig. S4. Defnition of mathematical measure. We defned abnormal regions (aR0 and aR1) whose nAC0 and nAC1, respectively, were greater than the mean + 2 SD of the age- and sex-matched values. Te relative frequency distribution of the aR0 and aR1 for both healthy controls and patients are shown in Supplementary Figure S5. As shown, the distributions were not normal. Chi-square tests revealed that distributions for the patients were sig- 2 2 nifcantly diferent from control data (χ = 147, p < 0.00001 for aR0; χ = 23.04, p = 0.00078 for aR1). Te median number of aR0 and aR1 for the patients were 19.5 and 18.0, respectively. Te number of aR0 was signifcantly higher than that for the controls (median = 10.5) (z = 3.5901, p = 0.00033, Wilcoxon rank sum test), whereas the number of aR1 was not signifcantly diferent from that for the controls (median = 14) (z = 0.7833, p > 0.05).
Load more

Recommended publications
  • A Study Finalised to the Development of a BCI for Locked-In Subjects Based on Single Trial
    POLITECNICO DI TORINO Corso di Laurea in Ingegneria Biomedica Tesi di Laurea Magistrale Habit and neural fatigue: a study finalised to the development of a BCI for Locked-In subjects based on Single Trial EEG Relatore Prof.ssa Gabriella Olmo Irene Rechichi Correlatore: Ing. Vito De Feo Luglio 2019 A Lorenzo per il rumore e il silenzio Abstract Author: Irene RECHICHI The Locked-In Syndrome is a medical condition regarding awake subjects that are aware and conscious but are not able to communicate verbally and physically; they are subjected to complete paralysis of almost all voluntary skeletal muscles, except for those who regulate vertical eye movements and eye-blinking. This condition is also described as pseudocoma and is mainly due to ventral pontine injuries. The future aim of this research project is to develop a BCI for single trial EEG analysis, that would be able to recognize specific patterns in the electrical activity of the brain, called movement-related cortical potentials. Among these event-related po- tentials, those of great interest for this study are readiness potentials, that generate when volitional movements are performed. The research work was divided into two parts: the experimental data collection and subsequent data analysis; habit and per- ceived tiredness can be listed among the factors that affect the readiness potential. In this preparatory study, the aim was to find evidence of that. Experimental data collection took several months and involved healthy subjects of age 20 to 60 and one injured subject, in minimally conscious state. The subjects underwent completely voluntary and semivoluntary tasks. The event-related potentials were extracted by simple averaging of the trials; the epochs ended with muscular activation.
    [Show full text]
  • Electrocorticography Evidence of Tactile Responses in Visual Cortices
    UvA-DARE (Digital Academic Repository) Electrocorticography Evidence of Tactile Responses in Visual Cortices Gaglianese, A.; Branco, M.P.; Groen, I.I.A.; Benson, N.C.; Vansteensel, M.J.; Murray, M.M.; Petridou, N.; Ramsey, N.F. DOI 10.1007/s10548-020-00783-4 Publication date 2020 Document Version Final published version Published in Brain Topography License CC BY Link to publication Citation for published version (APA): Gaglianese, A., Branco, M. P., Groen, I. I. A., Benson, N. C., Vansteensel, M. J., Murray, M. M., Petridou, N., & Ramsey, N. F. (2020). Electrocorticography Evidence of Tactile Responses in Visual Cortices. Brain Topography, 33(5), 559–570. https://doi.org/10.1007/s10548-020-00783-4 General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam (https://dare.uva.nl) Download date:03 Oct 2021 Brain Topography (2020) 33:559–570 https://doi.org/10.1007/s10548-020-00783-4 ORIGINAL PAPER Electrocorticography Evidence of Tactile Responses in Visual Cortices Anna Gaglianese1,2,3 · Mariana P.
    [Show full text]
  • EEG Glossary
    EEG Glossary The first attempt to systematically propose a syllabus for Activation procedure Any procedure designed to modu- electroencephalographers was made by O’Leary and Knott late EEG activity, for instance to enhance physiologi- who in 1955 published in the EEG Journal “Some Minimal cal waveforms or elicit abnormal paroxysmal activity. Essentials for Clinical Electroencephalographers” [1]. In the Examples include eye closing, hyperventilation, photic following decades, with the EEG being increasingly used in stimulation, natural or drug-induced sleep, sensory stimu- the experimental and clinical field, need to adopt a language lation (acoustic, somatosensory, or pain). as common as possible between various laboratories world- Activity, EEG An EEG wave or sequence of waves of wide became even more pressing. In fact, the multiplicity of cerebral origin. terms generated (and sometimes still generates) confusion Alpha band Frequency band of 8–13 Hz inclusive. Greek and misinterpretations, promoting misdiagnosis and making letter: α. it difficult to compare data between different laboratories. Alpha rhythm Rhythm at 8–13 Hz inclusive occurring To overcome this risk, in 1974 “A Glossary of Terms,” most during wakefulness over the posterior regions of the head, commonly used by “Clinical Electroencephalographers,” was generally with maximum amplitudes over the occipital published in the EEG Journal; this glossary was the result of areas. Amplitude varies but is mostly below 50 μV in the the work of a group of experts from the International Federation adult, but often much higher in children. Best seen with of Clinical Neurophysiology (IFCN) led by Chatrian [2]. the eyes closed, during physical relaxation and relative Thanks to this document, it was for the first time officially mental inactivity.
    [Show full text]
  • Intraoperative Electrocorticography
    Conference Proceeding Intraoperative electrocorticography Gabriela Alcaraz, Pirjo Manninen Abstract Intraoperative electrocorticography (ECoG) is the recording of electrophysiological activity from electrodes placed directly on the exposed surface of brain, during surgery for epilepsy and tumor resection. The ECoG is helpful in defining the seizure onset and spread within the cortical surface and delineation of the interface between epileptogenic zones and functional cortex substance of the brain. Intraoperative ECoG is an invasive procedure, it is performed during surgery mostly commonly during awake craniotomy but at times during general anaesthesia. As most anesthetic agents will affect ECoG, they should be minimized or stopped prior to any recording. Activation of intraoperative epileptiform activity may also be required if there are no spontaneous discharges. The appropriate management of the anesthetic during the time of ECoG is critical for its success. There are limitations and some controversies to all the uses of intraoperative ECoG, thus each center will set their own indications, criteria, and protocols. Key words: Electrocorticography, epilepsy, neuroanaesthesia INTRODUCTION localisation and complete removal of the epileptogenic zone.[3,4] The epileptogenic zone includes all the areas Intraoperative electrocorticography (ECoG) is the of brain that generate spontaneous epileptic seizures. recording of electrophysiological activity from Though there is some controversy, ECoG, an invasive electrodes placed directly on the exposed surface of a technique, still plays an important role in the surgical brain, most commonly during the surgical treatment treatment of patients with epilepsy. The effects of [1-4] of epilepsy. The first use of intraoperative ECoG anaesthetic agents on intraoperative ECoG is an recordings was performed by Foerster and Alternberger important consideration for the anaesthesiologist in in 1935.
    [Show full text]
  • Magnetoencephalography: Clinical and Research Practices
    brain sciences Review Magnetoencephalography: Clinical and Research Practices Jennifer R. Stapleton-Kotloski 1,2,*, Robert J. Kotloski 3,4 ID , Gautam Popli 1 and Dwayne W. Godwin 1,5 1 Department of Neurology, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA; [email protected] (G.P.); [email protected] (D.W.G.) 2 Research and Education, W. G. “Bill” Hefner Salisbury VAMC, Salisbury, NC 28144, USA 3 Department of Neurology, William S Middleton Veterans Memorial Hospital, Madison, WI 53705, USA; [email protected] 4 Department of Neurology, University of Wisconsin School of Medicine and Public Health, Madison, WI 53726, USA 5 Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC 27101, USA * Correspondence: [email protected]; Tel.: +1-336-716-5243 Received: 28 June 2018; Accepted: 11 August 2018; Published: 17 August 2018 Abstract: Magnetoencephalography (MEG) is a neurophysiological technique that detects the magnetic fields associated with brain activity. Synthetic aperture magnetometry (SAM), a MEG magnetic source imaging technique, can be used to construct both detailed maps of global brain activity as well as virtual electrode signals, which provide information that is similar to invasive electrode recordings. This innovative approach has demonstrated utility in both clinical and research settings. For individuals with epilepsy, MEG provides valuable, nonredundant information. MEG accurately localizes the irritative zone associated with interictal spikes, often detecting epileptiform activity other methods cannot, and may give localizing information when other methods fail. These capabilities potentially greatly increase the population eligible for epilepsy surgery and improve planning for those undergoing surgery. MEG methods can be readily adapted to research settings, allowing noninvasive assessment of whole brain neurophysiological activity, with a theoretical spatial range down to submillimeter voxels, and in both humans and nonhuman primates.
    [Show full text]
  • Graphene-Based Carbon-Layered Electrode Array Technology for Neural Imaging and Optogenetic Applications
    ARTICLE Received 30 Apr 2014 | Accepted 12 Sep 2014 | Published 20 Oct 2014 DOI: 10.1038/ncomms6258 OPEN Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications Dong-Wook Park1,*, Amelia A. Schendel2,*, Solomon Mikael1,*, Sarah K. Brodnick3, Thomas J. Richner3, Jared P. Ness3, Mohammed R. Hayat3, Farid Atry4, Seth T. Frye4, Ramin Pashaie4, Sanitta Thongpang5, Zhenqiang Ma1,2 & Justin C. Williams2,3 Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and com- pliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at 490% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications. 1 Department of Electrical and Computer Engineering, University of Wisconsin—Madison, Madison, Wisconsin 53706, USA. 2 Materials Science Program, University of Wisconsin—Madison, Madison, Wisconsin 53706, USA. 3 Department of Biomedical Engineering, University of Wisconsin—Madison, Madison, Wisconsin 53706, USA.
    [Show full text]
  • Interictal High-Frequency Oscillations Generated by Seizure Onset and Eloquent Areas May Be Differentially Coupled with Different Slow Waves
    HHS Public Access Author manuscript Author ManuscriptAuthor Manuscript Author Clin Neurophysiol Manuscript Author . Author Manuscript Author manuscript; available in PMC 2017 June 01. Published in final edited form as: Clin Neurophysiol. 2016 June ; 127(6): 2489–2499. doi:10.1016/j.clinph.2016.03.022. Interictal high-frequency oscillations generated by seizure onset and eloquent areas may be differentially coupled with different slow waves Yutaka Nonoda, MD1, Makoto Miyakoshi, PhD4, Alejandro Ojeda, PhD4, Scott Makeig, PhD4, Csaba Juhász, MD, PhD1,2, Sandeep Sood, MD3, and Eishi Asano, MD, PhD1,2,* 1Pediatrics, Children’s Hospital of Michigan, Wayne State University, Detroit, MI, USA 2Neurology, Children’s Hospital of Michigan, Wayne State University, Detroit, MI, USA 3Neurosurgery, Children’s Hospital of Michigan, Wayne State University, Detroit, MI, USA 4Swartz Center for Computational Neuroscience, Institute for Neural Computation, University of California San Diego, La Jolla, CA, USA Abstract OBJECTIVE—High-frequency oscillations (HFOs) can be spontaneously generated by seizure- onset and functionally-important areas. We determined if consideration of the spectral frequency bands of coupled slow-waves could distinguish between epileptogenic and physiological HFOs. METHODS—We studied a consecutive series of 13 children with focal epilepsy who underwent extraoperative electrocorticography. We measured the occurrence rate of HFOs during slow-wave sleep at each electrode site. We subsequently determined the performance of HFO rate for localization of seizure-onset sites and undesirable detection of nonepileptic sensorimotor-visual sites defined by neurostimulation. We likewise determined the predictive performance of modulation index: MI(XHz)&(YHz), reflecting the strength of coupling between amplitude of HFOsXHz and phase of slow-waveYHz.
    [Show full text]
  • Multiple Mechanisms Link Prestimulus Neural Oscillations to Sensory Responses
    RESEARCH ARTICLE Multiple mechanisms link prestimulus neural oscillations to sensory responses Luca Iemi1,2,3*, Niko A Busch4,5, Annamaria Laudini6, Saskia Haegens1,7, Jason Samaha8, Arno Villringer2,6, Vadim V Nikulin2,3,9,10* 1Department of Neurological Surgery, Columbia University College of Physicians and Surgeons, New York City, United States; 2Department of Neurology, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany; 3Centre for Cognition and Decision Making, Institute for Cognitive Neuroscience, National Research University Higher School of Economics, Moscow, Russian Federation; 4Institute of Psychology, University of Mu¨ nster, Mu¨ nster, Germany; 5Otto Creutzfeldt Center for Cognitive and Behavioral Neuroscience, University of Mu¨ nster, Mu¨ nster, Germany; 6Berlin School of Mind and Brain, Humboldt- Universita¨ t zu Berlin, Berlin, Germany; 7Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, Netherlands; 8Department of Psychology, University of California, Santa Cruz, Santa Cruz, United States; 9Department of Neurology, Charite´-Universita¨ tsmedizin Berlin, Berlin, Germany; 10Bernstein Center for Computational Neuroscience, Berlin, Germany Abstract Spontaneous fluctuations of neural activity may explain why sensory responses vary across repeated presentations of the same physical stimulus. To test this hypothesis, we recorded electroencephalography in humans during stimulation with identical visual stimuli and analyzed how prestimulus neural oscillations modulate different stages of sensory processing reflected by distinct components of the event-related potential (ERP). We found that strong prestimulus alpha- and beta-band power resulted in a suppression of early ERP components (C1 and N150) and in an *For correspondence: amplification of late components (after 0.4 s), even after controlling for fluctuations in 1/f aperiodic [email protected] (LI); signal and sleepiness.
    [Show full text]
  • High-Frequency Oscillations and Their Importance in Epilepsy
    olog eur ica N l D f i o s l o a r n d r e u r s o J Gonen, J Neurol Disord 2014, 2:6 Neurological Disorders DOI: 10.4172/2329-6895.1000183 ISSN: 2329-6895 Review Article Open Access High-Frequency Oscillations and Their Importance in Epilepsy Ofer Michael Gonen Department of Neurology, Assaf Harofeh Medical Center, Israel *Corresponding author: Ofer M. Gonen, The Neurology Department, Assaf Harofeh Medical Center, Zerifin, 70300, Israel, Tel: +972-8-9779181; Fax: +972-8-9779183; E-mail: [email protected] Rec date: Aug 15, 2014, Acc date: Oct 19, 2014, Pub date: Oct 21, 2014 Copyright: © 2014 Gonen OM. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract High-frequency oscillations are changes in electrical potentials in the EEG in frequencies above 80 Hz. In recent years it was discovered that these oscillations have great importance both in physiologic processes and as an expression of epileptogenic areas in the cerebral cortex. The measurement of these oscillations via depth-electrodes during pre-surgical evaluation of epilepsy patients has been proven to be an important tool in improving the ability to delineate exactly the area which should be resected, in case such an operation is feasible. New technical developments enable the acquisition of high-frequency oscillations from scalp electrodes as well, which could have great importance in brain research and care of epilepsy patients in the future.
    [Show full text]
  • Intra-Operative Electrocorticography in Lesional Epilepsy
    Epilepsy Research (2010) 89, 133—141 journal homepage: www.elsevier.com/locate/epilepsyres Intra-operative electrocorticography in lesional epilepsy M. Tripathi, A. Garg, S. Gaikwad, C.S. Bal, Sarkar Chitra, K. Prasad, H.H. Dash, B.S. Sharma, P. Sarat. Chandra ∗ Neurosciences Center, All India Institute of Medical Sciences, New Delhi, India Received 19 June 2009; received in revised form 26 November 2009; accepted 26 December 2009 Available online 15 January 2010 KEYWORDS Summary Intra-operative electrocorticography (ECoG) is useful in epilepsy surgery to delin- Electrocorticography; eate margins of epileptogenic zone, guide resection and evaluate completeness of resection in Intra-operative surgically remediable intractable epilepsies. The study evaluated 157 cases (2000—2008). The electrocorticography; preoperative evaluation also included ictal SPECT (122) and PET in 32 cases. All were lesional Epilepsy; cases, 51% (81) of patients had >1 seizure/day and another 1/3rd (51) had >1/week. Pre and Intractable epilepsy; post resection ECoG was performed in all cases. A total of 372 recordings were performed Epilepsy surgery; in 157 cases. Second post-operative recordings (42) and third post-operative recordings (16) Electrical mapping were also performed. Site of recordings included lateral temporal (61), frontal (39), parietal (37), hippocampal (16) and occipital (4). 129/157 cases (82%) showing improvement on ECoG, 30/42 cases showed improvement in 2nd post resection, 8/16 showed improvement in the 3rd post-operative ECoG. 116/157 (73%) patients had good outcome (Engel I and II) at follow up (12—94 months, mean 18.2 months). Of these, 104 patients (80%) showed improvement on post- operative ECoG.
    [Show full text]
  • A Validation Study of the Use of Near-Infrared Spectroscopy Imaging in Primary and Secondary Motor Areas of the Human Brain
    YEBEH-04302; No of Pages 8 Epilepsy & Behavior xxx (2015) xxx–xxx Contents lists available at ScienceDirect Epilepsy & Behavior journal homepage: www.elsevier.com/locate/yebeh A validation study of the use of near-infrared spectroscopy imaging in primary and secondary motor areas of the human brain Christoph Drenckhahn a,b,d, Stefan P. Koch d,JohannesDümmlere, Matthias Kohl-Bareis f, Jens Steinbrink a,d, Jens P. Dreier a,b,c,d,⁎ a Center for Stroke Research Berlin, Charité University Medicine Berlin, Berlin, Germany b Department of Neurology, Charité University Medicine Berlin, Berlin, Germany c Department of Experimental Neurology, Charité University Medicine Berlin, Berlin, Germany d Berlin Neuroimaging Center, Charité University Medicine Berlin, Berlin, Germany e Department of Anaesthesiology and Intensive Care Medicine, Christian-Albrechts University, Kiel, Germany f RheinAhrCampus, University of Applied Sciences Koblenz, Remagen, Germany article info abstract Article history: The electroencephalographically measured Bereitschafts (readiness)-potential in the supplementary motor area Accepted 3 April 2015 (SMA) serves as a signature of the preparation of motor activity. Using a multichannel, noninvasive near-infrared Available online xxxx spectroscopy (NIRS) imager, we studied the vascular correlate of the readiness potential. Sixteen healthy subjects performed a self-paced or externally triggered motor task in a single or repetitive Keywords: pattern, while NIRS simultaneously recorded the task-related responses of deoxygenated hemoglobin (HbR) in Human motor system Functional activation the primary motor area (M1) and the SMA. fi Primary motor area Right-hand movements in the repetitive sequence trial elicited a signi cantly greater HbR response in both the Supplementary motor area SMA and the left M1 compared to left-hand movements.
    [Show full text]
  • Neurophysiological and Computational Principles of Cortical Rhythms in Cognition
    Physiol Rev 90: 1195–1268, 2010; doi:10.1152/physrev.00035.2008. Neurophysiological and Computational Principles of Cortical Rhythms in Cognition XIAO-JING WANG Department of Neurobiology and Kavli Institute of Neuroscience, Yale University School of Medicine, New Haven, Connecticut I. Introduction 1196 A. Synchronization and stochastic neuronal activity in the cerebral cortex 1196 B. Cortical oscillations associated with cognitive behaviors 1197 C. Interplay between neuronal and synaptic dynamics 1199 D. Organization of this review 1200 II. Single Neurons as Building Blocks of Network Oscillations 1200 A. Phase-response properties of type I and type II neurons 1201 B. Resonance 1203 C. Subthreshold and mixed-mode membrane oscillations 1204 D. Rhythmic bursting 1206 III. Basic Mechanisms for Network Synchronization 1207 A. Mutual excitation between pyramidal neurons 1207 B. Inhibitory interneuronal network 1208 C. Excitatory-inhibitory feedback loop 1209 D. Synaptic filtering 1211 E. Slow negative feedback 1211 F. Electrical coupling 1212 G. Correlation-induced stochastic synchrony 1213 IV. Network Architecture 1213 A. All-to-all networks: synchrony, asynchrony, and clustering 1214 B. Sparse random networks 1214 C. Complex networks 1214 D. Spatially structured networks: propagating waves 1217 E. Interaction between diverse cell types 1219 F. Interaction across multiple network modules 1219 V. Synchronous Rhythms With Irregular Neural Activity 1222 A. Local field oscillations versus stochastic spike discharges of single cells 1222 B. Sparsely synchronized oscillations 1224 C. Specific cases: fast cortical rhythms 1227 VI. Functional Implications: Synchronization and Long-Distance Communication 1229 A. Methodological considerations 1229 B. Phase coding 1232 C. Learning and memory 1235 D. Multisensory integration 1236 E.
    [Show full text]