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Nielsen TGNDS, Dancause N, Janjua TAM, Andreis FR, Kjærgaard B, Jensen W. Porcine Model of Cerebral Ischemic Stroke Utilizing Intracortical Recordings for the Continuous Monitoring of the Ischemic Area. SENSORS (BASEL, SWITZERLAND) 2024; 24:2967. [PMID: 38793822 PMCID: PMC11124877 DOI: 10.3390/s24102967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 05/01/2024] [Accepted: 05/03/2024] [Indexed: 05/26/2024]
Abstract
PURPOSE Our aim was to use intracortical recording to enable the tracking of ischemic infarct development over the first few critical hours of ischemia with a high time resolution in pigs. We employed electrophysiological measurements to obtain quick feedback on neural function, which might be useful for screening, e.g., for the optimal dosage and timing of agents prior to further pre-clinical evaluation. METHODS Micro-electrode arrays containing 16 (animal 1) or 32 electrodes (animal 2-7) were implanted in the primary somatosensory cortex of seven female pigs, and continuous electrical stimulation was applied at 0.2 Hz to a cuff electrode implanted on the ulnar nerve. Ischemic stroke was induced after 30 min of baseline recording by injection of endothelin-1 onto the cortex adjacent to the micro-electrode array. Evoked responses were extracted over a moving window of 180 s and averaged across channels as a measure of cortical excitability. RESULTS Across the animals, the cortical excitability was significantly reduced in all seven 30 min segments following endothelin-1 injection, as compared to the 30 min preceding this intervention. This difference was not explained by changes in the anesthesia, ventilation, end-tidal CO2, mean blood pressure, heart rate, blood oxygenation, or core temperature, which all remained stable throughout the experiment. CONCLUSIONS The animal model may assist in maturing neuroprotective approaches by testing them in an accessible model of resemblance to human neural and cardiovascular physiology and body size. This would constitute an intermediate step for translating positive results from rodent studies into human application, by more efficiently enabling effective optimization prior to chronic pre-clinical studies in large animals.
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Affiliation(s)
| | - Numa Dancause
- Département de Neurosciences, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montréal, QC H3C 3J7, Canada
| | - Taha Al Muhammadee Janjua
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Selma Lagerløfs Vej 249, 9260 Gistrup, Denmark
| | - Felipe Rettore Andreis
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Selma Lagerløfs Vej 249, 9260 Gistrup, Denmark
| | - Benedict Kjærgaard
- Department of Cardiothoracic Surgery, Aalborg University Hospital, Hobrovej 18, 9000 Aalborg, Denmark
| | - Winnie Jensen
- Bevica Center, Department of Health Science and Technology, Aalborg University, Selma Lagerløfs Vej 249, 9260 Gistrup, Denmark
- Center for Neuroplasticity and Pain (CNAP), Department of Health Science and Technology, Aalborg University, Selma Lagerløfs Vej 249, 9260 Gistrup, Denmark
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Update to the dataset of cerebral ischemia in juvenile pigs with evoked potentials. Sci Data 2021; 8:248. [PMID: 34556666 PMCID: PMC8460715 DOI: 10.1038/s41597-021-01029-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 08/12/2021] [Indexed: 11/23/2022] Open
Abstract
We expand from a spontaneous to an evoked potentials (EP) data set of brain electrical activities as electrocorticogram (ECoG) and electrothalamogram (EThG) in juvenile pig under various sedation, ischemia and recovery states. This EP data set includes three stimulation paradigms: auditory (AEP, 40 and 2000 Hz), sensory (SEP, left and right maxillary nerve) and high-frequency oscillations (HFO) SEP. This permits derivation of electroencephalogram (EEG) biomarkers of corticothalamic communication under these conditions. The data set is presented in full band sampled at 2000 Hz. We provide technical validation of the evoked responses for the states of sedation, ischemia and recovery. This extended data set now permits mutual inferences between spontaneous and evoked activities across the recorded modalities. Future studies on the dataset may contribute to the development of new brain monitoring technologies, which will facilitate the prevention of neurological injuries. Measurement(s) | Abnormal auditory evoked potentials • Abnormality of somatosensory evoked potentials • high frequency oscillations • brain activity | Technology Type(s) | Electrocorticography • electrothalamography | Factor Type(s) | anesthesia • analgosedation • sedation • cerebral ischemia | Sample Characteristic - Organism | Sus scrofa |
Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.16462875
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Tripathi K, Zhang T, McDannold N, Zhang YZ, Ehnholm G, Okada Y. Direct Activation of Cortical Neurons in the Primary Somatosensory Cortex of the Rat in Vivo Using Focused Ultrasound. ULTRASOUND IN MEDICINE & BIOLOGY 2020; 46:2349-2360. [PMID: 32620386 PMCID: PMC7431189 DOI: 10.1016/j.ultrasmedbio.2020.06.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 05/26/2020] [Accepted: 06/03/2020] [Indexed: 06/11/2023]
Abstract
We address the recent controversy over whether focused ultrasound (FUS) activates cortical neurons directly or indirectly by initially activating auditory pathways. We obtained two types of evidence that FUS can directly activate cortical neurons. The depth profile of the local field potential (LFP) in the barrel cortex of the rat in vivo indicated a generator was located within the cortical gray matter. The onset and peak latencies of the initial component p1 were 3.2 ± 0.25 ms (mean ± standard error of the mean) and 7.6 ± 0.12 ms, respectively, for the direct cortical response (DCR), 6.8 ± 0.40 and 14.3 ± 0.54 ms for the FUS-evoked LFP (4 MHz, 3.2 MPa, 50 or 300 µs/pulse, 1-20 pulses at 1 kHz) and 6.9 ± 0.51 and 15.8 ± 0.94 ms for the LFP evoked by 1-ms deflection of the C2 whisker projecting to the same area. The peak latency of the FUS p1 was statistically (t-test) longer than the DCR, but shorter than the whisker p1 at p < 0.005.
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Affiliation(s)
- Kush Tripathi
- Division of Newborn Medicine, Dept. Pediatrics, Boston Children's Hospital/Harvard Medical School, Boston, Massachusetts, USA; Indian Institute of Technology, Madras, India
| | - Tongsheng Zhang
- Department of Neurosurgery, University of New Mexico School of Medicine, Albuquerque, New Mexico, USA
| | - Nathan McDannold
- Focused Ultrasound Laboratory, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts, USA
| | - Yong-Zhi Zhang
- Focused Ultrasound Laboratory, Brigham and Women's Hospital/Harvard Medical School, Boston, Massachusetts, USA
| | - Gösta Ehnholm
- Department of Neurosciences and Biomedical Engineering, Aalto University, Otaniemi, Finland
| | - Yoshio Okada
- Division of Newborn Medicine, Dept. Pediatrics, Boston Children's Hospital/Harvard Medical School, Boston, Massachusetts, USA.
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Comanducci A, Boly M, Claassen J, De Lucia M, Gibson RM, Juan E, Laureys S, Naccache L, Owen AM, Rosanova M, Rossetti AO, Schnakers C, Sitt JD, Schiff ND, Massimini M. Clinical and advanced neurophysiology in the prognostic and diagnostic evaluation of disorders of consciousness: review of an IFCN-endorsed expert group. Clin Neurophysiol 2020; 131:2736-2765. [PMID: 32917521 DOI: 10.1016/j.clinph.2020.07.015] [Citation(s) in RCA: 91] [Impact Index Per Article: 22.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 07/06/2020] [Accepted: 07/26/2020] [Indexed: 12/13/2022]
Abstract
The analysis of spontaneous EEG activity and evoked potentialsis a cornerstone of the instrumental evaluation of patients with disorders of consciousness (DoC). Thepast few years have witnessed an unprecedented surge in EEG-related research applied to the prediction and detection of recovery of consciousness after severe brain injury,opening up the prospect that new concepts and tools may be available at the bedside. This paper provides a comprehensive, critical overview of bothconsolidated and investigational electrophysiological techniquesfor the prognostic and diagnostic assessment of DoC.We describe conventional clinical EEG approaches, then focus on evoked and event-related potentials, and finally we analyze the potential of novel research findings. In doing so, we (i) draw a distinction between acute, prolonged and chronic phases of DoC, (ii) attempt to relate both clinical and research findings to the underlying neuronal processes and (iii) discuss technical and conceptual caveats.The primary aim of this narrative review is to bridge the gap between standard and emerging electrophysiological measures for the detection and prediction of recovery of consciousness. The ultimate scope is to provide a reference and common ground for academic researchers active in the field of neurophysiology and clinicians engaged in intensive care unit and rehabilitation.
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Affiliation(s)
- A Comanducci
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy
| | - M Boly
- Department of Neurology and Department of Psychiatry, University of Wisconsin, Madison, USA; Wisconsin Institute for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin-Madison, Madison, USA
| | - J Claassen
- Department of Neurology, Columbia University Medical Center, New York Presbyterian Hospital, New York, NY, USA
| | - M De Lucia
- Laboratoire de Recherche en Neuroimagerie, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - R M Gibson
- The Brain and Mind Institute and the Department of Physiology and Pharmacology, Western Interdisciplinary Research Building, N6A 5B7 University of Western Ontario, London, Ontario, Canada
| | - E Juan
- Wisconsin Institute for Sleep and Consciousness, Department of Psychiatry, University of Wisconsin-Madison, Madison, USA; Amsterdam Brain and Cognition, Department of Psychology, University of Amsterdam, Amsterdam, the Netherlands
| | - S Laureys
- Coma Science Group, Centre du Cerveau, GIGA-Consciousness, University and University Hospital of Liège, 4000 Liège, Belgium; Fondazione Europea per la Ricerca Biomedica Onlus, Milan 20063, Italy
| | - L Naccache
- Inserm U 1127, CNRS UMR 7225, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France; Sorbonne Université, UPMC Université Paris 06, Faculté de Médecine Pitié-Salpêtrière, Paris, France
| | - A M Owen
- The Brain and Mind Institute and the Department of Physiology and Pharmacology, Western Interdisciplinary Research Building, N6A 5B7 University of Western Ontario, London, Ontario, Canada
| | - M Rosanova
- Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, Italy; Fondazione Europea per la Ricerca Biomedica Onlus, Milan 20063, Italy
| | - A O Rossetti
- Neurology Service, Department of Clinical Neurosciences, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - C Schnakers
- Research Institute, Casa Colina Hospital and Centers for Healthcare, Pomona, CA, USA
| | - J D Sitt
- Inserm U 1127, CNRS UMR 7225, Institut du Cerveau et de la Moelle épinière, ICM, Paris, France
| | - N D Schiff
- Feil Family Brain and Mind Research Institute, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - M Massimini
- IRCCS Fondazione Don Carlo Gnocchi, Milan, Italy; Department of Biomedical and Clinical Sciences "L. Sacco", University of Milan, Milan, Italy
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Neymotin SA, Daniels DS, Caldwell B, McDougal RA, Carnevale NT, Jas M, Moore CI, Hines ML, Hämäläinen M, Jones SR. Human Neocortical Neurosolver (HNN), a new software tool for interpreting the cellular and network origin of human MEG/EEG data. eLife 2020; 9:e51214. [PMID: 31967544 PMCID: PMC7018509 DOI: 10.7554/elife.51214] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/22/2020] [Indexed: 12/26/2022] Open
Abstract
Magneto- and electro-encephalography (MEG/EEG) non-invasively record human brain activity with millisecond resolution providing reliable markers of healthy and disease states. Relating these macroscopic signals to underlying cellular- and circuit-level generators is a limitation that constrains using MEG/EEG to reveal novel principles of information processing or to translate findings into new therapies for neuropathology. To address this problem, we built Human Neocortical Neurosolver (HNN, https://hnn.brown.edu) software. HNN has a graphical user interface designed to help researchers and clinicians interpret the neural origins of MEG/EEG. HNN's core is a neocortical circuit model that accounts for biophysical origins of electrical currents generating MEG/EEG. Data can be directly compared to simulated signals and parameters easily manipulated to develop/test hypotheses on a signal's origin. Tutorials teach users to simulate commonly measured signals, including event related potentials and brain rhythms. HNN's ability to associate signals across scales makes it a unique tool for translational neuroscience research.
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Affiliation(s)
- Samuel A Neymotin
- Department Neuroscience, Carney Institute for Brain SciencesBrown UniversityProvidenceUnited States
- Center for Biomedical Imaging and NeuromodulationNathan S. Kline Institute for Psychiatric ResearchOrangeburgUnited States
| | - Dylan S Daniels
- Department Neuroscience, Carney Institute for Brain SciencesBrown UniversityProvidenceUnited States
| | - Blake Caldwell
- Department Neuroscience, Carney Institute for Brain SciencesBrown UniversityProvidenceUnited States
| | - Robert A McDougal
- Department NeuroscienceYale UniversityNew HavenUnited States
- Department of BiostatisticsYale UniversityNew HavenUnited States
| | | | - Mainak Jas
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestownUnited States
- Harvard Medical SchoolBostonUnited States
| | - Christopher I Moore
- Department Neuroscience, Carney Institute for Brain SciencesBrown UniversityProvidenceUnited States
| | - Michael L Hines
- Department NeuroscienceYale UniversityNew HavenUnited States
| | - Matti Hämäläinen
- Athinoula A. Martinos Center for Biomedical ImagingMassachusetts General HospitalCharlestownUnited States
- Harvard Medical SchoolBostonUnited States
| | - Stephanie R Jones
- Department Neuroscience, Carney Institute for Brain SciencesBrown UniversityProvidenceUnited States
- Center for Neurorestoration and NeurotechnologyProvidence VAMCProvidenceUnited States
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van Putten MJ, Jansen C, Tjepkema-Cloostermans MC, Beernink TM, Koot R, Bosch F, Beishuizen A, Hofmeijer J. Postmortem histopathology of electroencephalography and evoked potentials in postanoxic coma. Resuscitation 2019; 134:26-32. [DOI: 10.1016/j.resuscitation.2018.12.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/17/2018] [Accepted: 12/10/2018] [Indexed: 02/04/2023]
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Gaetz W, Jurkiewicz MT, Kessler SK, Blaskey L, Schwartz ES, Roberts TP. Neuromagnetic responses to tactile stimulation of the fingers: Evidence for reduced cortical inhibition for children with Autism Spectrum Disorder and children with epilepsy. Neuroimage Clin 2017; 16:624-633. [PMID: 28971012 PMCID: PMC5619996 DOI: 10.1016/j.nicl.2017.06.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 05/30/2017] [Accepted: 06/16/2017] [Indexed: 12/04/2022]
Abstract
The purpose of this study was to compare somatosensory responses from a group of children with epilepsy and a group of children with autism spectrum disorder (ASD), with age matched TD controls. We hypothesized that the magnitude of the tactile "P50m" somatosensory response would be reduced in both patient groups, possibly due to reduced GABAergic signaling as has been implicated in a variety of previous animal models and in vivo human MRS studies. We observed significant (~ 25%) decreases in tactile P50m dipole moment values from the source localized tactile P50m response, both for children with epilepsy and for children with ASD. In addition, the latency of the tactile P50m peak was observed to be equivalent between TD and ASD groups but was significantly delayed in children with epilepsy by ~ 6 ms. Our data support the hypothesis of impaired GABAergic signaling in both children with ASD and children with epilepsy. Further work is needed to replicate these findings and directly relate them to both in vivo measures of GABA via e.g. magnetic resonance spectroscopy and psychophysical assessments of somatosensory function, and behavioral indices.
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Affiliation(s)
- William Gaetz
- Lurie Family Foundations MEG Imaging Center, Department of Radiology, Children's Hospital of Philadelphia, United States
- Department of Radiology, Children’s Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
| | - Michael T. Jurkiewicz
- Department of Radiology, Children’s Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
| | - Sudha Kilaru Kessler
- Department of Neurology, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
- Department of Pediatrics, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
| | - Lisa Blaskey
- Lurie Family Foundations MEG Imaging Center, Department of Radiology, Children's Hospital of Philadelphia, United States
- Children's Hospital of Philadelphia, Department of Radiology and Center for Autism Research, United States
| | - Erin S. Schwartz
- Lurie Family Foundations MEG Imaging Center, Department of Radiology, Children's Hospital of Philadelphia, United States
- Department of Radiology, Children’s Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
| | - Timothy P.L. Roberts
- Lurie Family Foundations MEG Imaging Center, Department of Radiology, Children's Hospital of Philadelphia, United States
- Department of Radiology, Children’s Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, United States
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Sridharan KS, Højlund A, Johnsen EL, Sunde NA, Johansen LG, Beniczky S, Østergaard K. Differentiated effects of deep brain stimulation and medication on somatosensory processing in Parkinson's disease. Clin Neurophysiol 2017; 128:1327-1336. [PMID: 28570866 DOI: 10.1016/j.clinph.2017.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 03/14/2017] [Accepted: 04/19/2017] [Indexed: 12/31/2022]
Abstract
OBJECTIVES Deep brain stimulation (DBS) and dopaminergic medication effectively alleviate the motor symptoms in Parkinson's disease (PD) patients, but their effects on the sensory symptoms of PD are still not well understood. To explore early somatosensory processing in PD, we recorded magnetoencephalography (MEG) from thirteen DBS-treated PD patients and ten healthy controls during median nerve stimulation. METHODS PD patients were measured during DBS-treated, untreated and dopaminergic-medicated states. We focused on early cortical somatosensory processing as indexed by N20m, induced gamma augmentation (31-45Hz and 55-100Hz) and induced beta suppression (13-30Hz). PD patients' motor symptoms were assessed by UPDRS-III. RESULTS Using Bayesian statistics, we found positive evidence for differentiated effects of treatments on the induced gamma augmentation (31-45Hz) with highest gamma in the dopaminergic-medicated state and lowest in the DBS-treated and untreated states. In contrast, UPDRS-III scores showed beneficial effects of both DBS and dopaminergic medication on the patients' motor symptoms. Furthermore, treatments did not affect the amplitude of N20m. CONCLUSIONS Our results suggest differentiated effects of DBS and dopaminergic medication on cortical somatosensory processing in PD patients despite consistent ameliorating effects of both treatments on PD motor symptoms. SIGNIFICANCE The differentiated effect suggests differences in the effect mechanisms of the two treatments.
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Affiliation(s)
- Kousik Sarathy Sridharan
- Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark; Center of Functionally Integrative Neuroscience (CFIN), Aarhus University, Nørrebrogade 44, 8000 Aarhus, Denmark.
| | - Andreas Højlund
- Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark; Center of Functionally Integrative Neuroscience (CFIN), Aarhus University, Nørrebrogade 44, 8000 Aarhus, Denmark
| | - Erik Lisbjerg Johnsen
- Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark
| | - Niels Aagaard Sunde
- Department of Neurosurgery, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark
| | | | - Sándor Beniczky
- Department of Clinical Neurophysiology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark; Department of Clinical Neurophysiology, Danish Epilepsy Center, Kolonivej 1, 4293 Dianalund, Denmark
| | - Karen Østergaard
- Department of Neurology, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark; Center of Functionally Integrative Neuroscience (CFIN), Aarhus University, Nørrebrogade 44, 8000 Aarhus, Denmark
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Neural mechanisms of transient neocortical beta rhythms: Converging evidence from humans, computational modeling, monkeys, and mice. Proc Natl Acad Sci U S A 2016; 113:E4885-94. [PMID: 27469163 DOI: 10.1073/pnas.1604135113] [Citation(s) in RCA: 252] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human neocortical 15-29-Hz beta oscillations are strong predictors of perceptual and motor performance. However, the mechanistic origin of beta in vivo is unknown, hindering understanding of its functional role. Combining human magnetoencephalography (MEG), computational modeling, and laminar recordings in animals, we present a new theory that accounts for the origin of spontaneous neocortical beta. In our MEG data, spontaneous beta activity from somatosensory and frontal cortex emerged as noncontinuous beta events typically lasting <150 ms with a stereotypical waveform. Computational modeling uniquely designed to infer the electrical currents underlying these signals showed that beta events could emerge from the integration of nearly synchronous bursts of excitatory synaptic drive targeting proximal and distal dendrites of pyramidal neurons, where the defining feature of a beta event was a strong distal drive that lasted one beta period (∼50 ms). This beta mechanism rigorously accounted for the beta event profiles; several other mechanisms did not. The spatial location of synaptic drive in the model to supragranular and infragranular layers was critical to the emergence of beta events and led to the prediction that beta events should be associated with a specific laminar current profile. Laminar recordings in somatosensory neocortex from anesthetized mice and awake monkeys supported these predictions, suggesting this beta mechanism is conserved across species and recording modalities. These findings make several predictions about optimal states for perceptual and motor performance and guide causal interventions to modulate beta for optimal function.
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Invariance in current dipole moment density across brain structures and species: physiological constraint for neuroimaging. Neuroimage 2015; 111:49-58. [PMID: 25680520 DOI: 10.1016/j.neuroimage.2015.02.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Revised: 01/25/2015] [Accepted: 02/03/2015] [Indexed: 12/15/2022] Open
Abstract
Although anatomical constraints have been shown to be effective for MEG and EEG inverse solutions, there are still no effective physiological constraints. Strength of the current generator is normally described by the moment of an equivalent current dipole Q. This value is quite variable since it depends on size of active tissue. In contrast, the current dipole moment density q, defined as Q per surface area of active cortex, is independent of size of active tissue. Here we studied whether the value of q has a maximum in physiological conditions across brain structures and species. We determined the value due to the primary neuronal current (q primary) alone, correcting for distortions due to measurement conditions and secondary current sources at boundaries separating regions of differing electrical conductivities. The values were in the same range for turtle cerebellum (0.56-1.48 nAm/mm(2)), guinea pig hippocampus (0.30-1.34 nAm/mm(2)), and swine neocortex (0.18-1.63 nAm/mm(2)), rat neocortex (~2.2 nAm/mm(2)), monkey neocortex (~0.40 nAm/mm(2)) and human neocortex (0.16-0.77 nAm/mm(2)). Thus, there appears to be a maximum value across the brain structures and species (1-2 nAm/mm(2)). The empirical values closely matched the theoretical values obtained with our independently validated neural network model (1.6-2.8 nAm/mm(2) for initial spike and 0.7-3.1 nAm/mm(2) for burst), indicating that the apparent invariance is not coincidental. Our model study shows that a single maximum value may exist across a wide range of brain structures and species, varying in neuron density, due to fundamental electrical properties of neurons. The maximum value of q primary may serve as an effective physiological constraint for MEG/EEG inverse solutions.
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Correlates of a single cortical action potential in the epidural EEG. Neuroimage 2014; 109:357-67. [PMID: 25554430 PMCID: PMC4349634 DOI: 10.1016/j.neuroimage.2014.12.057] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 12/18/2014] [Accepted: 12/19/2014] [Indexed: 12/04/2022] Open
Abstract
To identify the correlates of a single cortical action potential in surface EEG, we recorded simultaneously epidural EEG and single-unit activity in the primary somatosensory cortex of awake macaque monkeys. By averaging over EEG segments coincident with more than hundred thousand single spikes, we found short-lived (≈ 0.5 ms) triphasic EEG deflections dominated by high-frequency components > 800 Hz. The peak-to-peak amplitude of the grand-averaged spike correlate was 80 nV, which matched theoretical predictions, while single-neuron amplitudes ranged from 12 to 966 nV. Combining these estimates with post-stimulus-time histograms of single-unit responses to median-nerve stimulation allowed us to predict the shape of the evoked epidural EEG response and to estimate the number of contributing neurons. These findings establish spiking activity of cortical neurons as a primary building block of high-frequency epidural EEG, which thus can serve as a quantitative macroscopic marker of neuronal spikes. Cortical spikes are coincident with short-lived (~ 0.5 ms) EEG deflections. Cortical spikes produce ~ 80 nV epidural EEG deflections at a distance of ~ 5 mm. EEG potentials due to spikes are dominated by high-frequency (> 800 Hz) components. High-frequency (> 800 Hz) EEG is a genuine macroscopic marker of spiking activity.
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Tanosaki M, Ishibashi H, Zhang T, Okada Y. Effective connectivity maps in the swine somatosensory cortex estimated from electrocorticography and validated with intracortical local field potential measurements. Brain Connect 2014; 4:100-11. [PMID: 24467225 DOI: 10.1089/brain.2013.0177] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Macroscopic techniques are increasingly being used to estimate functional connectivity in the brain, which provides valuable information about brain networks. In any such endeavors it is important to understand capabilities and limitations of each technique through direct validation, which is often lacking. This study evaluated a multiple dipole source analysis technique based on electrocorticography (ECOG) data in estimating effective connectivity maps and validated the technique with intracortical local field potential (LFP) recordings. The study was carried out in an animal model (swine) with a large brain to avoid complications caused by spreading of the volume current. The evaluation was carried out for the cortical projections from the trigeminal nerve and corticocortical connectivity from the first rostrum area (R1) in the primary somatosensory cortex. Stimulation of the snout and layer IV of the R1 did not activate all projection areas in each animal, although whenever an area was activated in a given animal, its location was consistent with the intracortical LFP. The two types of connectivity maps based on ECOG analysis were consistent with each other and also with those estimated from the intracortical LFP, although there were small discrepancies. The discrepancies in mean latency based on ECOG and LFP were all very small and nonsignificant: snout stimulation, -1.1-2.0 msec (contralateral hemisphere) and 3.9-8.5 msec (ipsilateral hemisphere); R1 stimulation, -1.4-2.2 msec for the ipsilateral and 0.6-1.4 msec for the contralateral hemisphere. Dipole source analysis based on ECOG appears to be quite useful for estimating effective connectivity maps in the brain.
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Affiliation(s)
- Masato Tanosaki
- 1 Department of Neurology, Hachinohe City Hospital , Hachinohe, Aomori, Japan
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Schorl M, Valerius-Kukula SJ, Kemmer TP. Median-evoked somatosensory potentials in severe brain injury: Does initial loss of cortical potentials exclude recovery? Clin Neurol Neurosurg 2014; 123:25-33. [DOI: 10.1016/j.clineuro.2014.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2013] [Revised: 04/27/2014] [Accepted: 05/03/2014] [Indexed: 11/28/2022]
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Lee S, Jones SR. Distinguishing mechanisms of gamma frequency oscillations in human current source signals using a computational model of a laminar neocortical network. Front Hum Neurosci 2013; 7:869. [PMID: 24385958 PMCID: PMC3866567 DOI: 10.3389/fnhum.2013.00869] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/28/2013] [Indexed: 01/14/2023] Open
Abstract
Gamma frequency rhythms have been implicated in numerous studies for their role in healthy and abnormal brain function. The frequency band has been described to encompass as broad a range as 30-150 Hz. Crucial to understanding the role of gamma in brain function is an identification of the underlying neural mechanisms, which is particularly difficult in the absence of invasive recordings in macroscopic human signals such as those from magnetoencephalography (MEG) and electroencephalography (EEG). Here, we studied features of current dipole (CD) signals from two distinct mechanisms of gamma generation, using a computational model of a laminar cortical circuit designed specifically to simulate CDs in a biophysically principled manner (Jones et al., 2007, 2009). We simulated spiking pyramidal interneuronal gamma (PING) whose period is regulated by the decay time constant of GABAA-mediated synaptic inhibition and also subthreshold gamma driven by gamma-periodic exogenous excitatory synaptic drive. Our model predicts distinguishable CD features created by spiking PING compared to subthreshold driven gamma that can help to disambiguate mechanisms of gamma oscillations in human signals. We found that gamma rhythms in neocortical layer 5 can obscure a simultaneous, independent gamma in layer 2/3. Further, we arrived at a novel interpretation of the origin of high gamma frequency rhythms (100-150 Hz), showing that they emerged from a specific temporal feature of CDs associated with single cycles of PING activity and did not reflect a separate rhythmic process. Last we show that the emergence of observable subthreshold gamma required highly coherent exogenous drive. Our results are the first to demonstrate features of gamma oscillations in human current source signals that distinguish cellular and circuit level mechanisms of these rhythms and may help to guide understanding of their functional role.
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Affiliation(s)
- Shane Lee
- Department of Neuroscience, Brown University Providence, RI, USA
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Chang WS, Kim BS, Jung HH, Kim K, Kwon HC, Lee YH, Chang JW. Decreased inhibitory neuronal activity in patients with frontal lobe brain tumors with seizure presentation: Preliminary study using magnetoencephalography. Acta Neurochir (Wien) 2013; 155:1449-57. [PMID: 23797730 DOI: 10.1007/s00701-013-1781-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 05/16/2013] [Indexed: 11/27/2022]
Abstract
BACKGROUND Although 30-50 % of patients with brain tumors experience epileptic seizure as the presenting clinical symptom, and another 10-30 % are at risk for developing epilepsy in the later stages of the disease, the mechanisms of tumor-related epileptogenesis are poorly understood. We used magnetoencephalography (MEG) to investigate sensory evoked fields (SEFs) in patients with frontal lobe brain tumors as a means of evaluating the neuronal activity of peri-tumoral cortex. METHODS Twelve patients with frontal lobe brain tumors underwent MEG. We calculated the equivalent current dipole strength of two components of the primary sensory cortical response (N20m and P35m) and compared the P35m/N20m ratio in the tumor hemisphere vs. the normal hemisphere. There were two subsets of patients: group I, in which P35m/N20m was higher in the tumor hemisphere (n= 7), and group II, in which P35m/N20m was higher in the normal hemisphere (n=5). We looked for associations between clinical factors and P35m/N20m within each group. RESULTS All patients with seizure presentation were in group I, whereas only two patients without seizure presentation were in group I (Fisher exact test, p=0.028). No other clinical factors were related to P35m/N20m. The mean ratio of P35m/N20m equivalent current dipole strength in patients with seizure presentation was 4.07 ± 2.38 in the tumor hemisphere and 2.00 ± 0.55 in the normal hemisphere. This difference was statistically significant (Mann-Whitney test, p=0.030). CONCLUSION The paradoxical increase in P35m/N20m in patients with seizure presentation suggests that decreased inhibitory neuronal activity is a potential cause of tumorrelated epilepsy.
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Affiliation(s)
- Won Seok Chang
- Department of Neurosurgery, Brain Research Institute, Yonsei University College of Medicine, 205 Seongsanno Seodaemun-gu, Seoul 120-752, Korea
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Saito T, Uga M, Tsuzuki D, Yokota H, Oguro K, Yamamoto T, Dan I, Watanabe E. Evoked potential mapping of the rostral region by frameless navigation system in Mexican hairless pig. J Neurosci Methods 2013; 212:100-5. [DOI: 10.1016/j.jneumeth.2012.09.027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Revised: 09/21/2012] [Accepted: 09/24/2012] [Indexed: 11/26/2022]
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Lim M, Kim JS, Chung CK. Modulation of somatosensory evoked magnetic fields by intensity of interfering stimuli in human somatosensory cortex: An MEG study. Neuroimage 2012; 61:660-9. [DOI: 10.1016/j.neuroimage.2012.04.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2011] [Revised: 03/12/2012] [Accepted: 04/02/2012] [Indexed: 10/28/2022] Open
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van Putten MJ. The N20 in post-anoxic coma: Are you listening? Clin Neurophysiol 2012; 123:1460-4. [DOI: 10.1016/j.clinph.2011.10.049] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/04/2011] [Accepted: 10/15/2011] [Indexed: 10/14/2022]
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Intracortical modulation of somatosensory evoked fields during movement: evidence for selective suppression of postsynaptic inhibition. Brain Res 2012; 1459:43-51. [PMID: 22564923 DOI: 10.1016/j.brainres.2012.04.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 03/11/2012] [Accepted: 04/11/2012] [Indexed: 11/24/2022]
Abstract
As accurate finger movements depend on guidance by afferent sensory feedback information, it is of interest to examine how the cortical processing of afferent signals is altered during movement states compared with rest. In the present study we evaluated afferent input to the primary somatosensory cortex (SI) in human subjects performing a finger opposition task. We recorded somatosensory evoked magnetic fields (SEFs) in 6 healthy subjects to stimulation of left and right median nerves in a resting condition and during active right-sided finger movements. At the left SI, the SEFs to right (moving hand) median nerve stimulation showed a selective and robust reduction of the P35m deflection during movement compared with rest, while there were only minor non-significant changes in the other SEF deflections, including N20m, which represents the 1st excitatory cortical event after stimulation. In contrast, at the right SI the SEFs to left (non-moving hand) median nerve stimulation were modified in the opposite direction: the P35m deflection was slightly enhanced during right-sided movement, there being no significant changes in the other deflections. The results thus show that the P35m SEF deflection can be selectively reduced during finger movements of the stimulated hand, and selectively enhanced if the movement is being performed with the fingers of the opposite hand. Because N20m was not changed, the modulation took place at the cortical level rather than in the afferent pathways. As the P35m SEF deflection likely represents postsynaptic IPSPs at SI, the results suggest that postsynaptic inhibition to somatosensory impulses from the moving part of the body is suppressed. Comparison of the present results with recent intracellular studies in behaving mice suggests that the P35m reduction specifically corresponds to a reduction in the activity of parvalbumin-containing fast-spiking inhibitory interneurons during movement. The results provide evidence that precision movements can be executed without this type of cortical postsynaptic inhibition.
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Machado C, Estévez M, Rodríguez R, Carrick FR, Melillo R, Leisman G. Bilateral N20 absence in post-anoxic coma: do you pay attention? Clin Neurophysiol 2011; 123:1264-6. [PMID: 22209660 DOI: 10.1016/j.clinph.2011.11.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 11/10/2011] [Accepted: 11/11/2011] [Indexed: 11/28/2022]
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Witzel T, Napadow V, Kettner NW, Vangel MG, Hämäläinen MS, Dhond RP. Differences in cortical response to acupressure and electroacupuncture stimuli. BMC Neurosci 2011; 12:73. [PMID: 21794103 PMCID: PMC3162932 DOI: 10.1186/1471-2202-12-73] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Accepted: 07/27/2011] [Indexed: 11/10/2022] Open
Abstract
Background FMRI studies focus on sub-cortical effects of acupuncture stimuli. The purpose of this study was to assess changes in primary somatosensory (S1) activity over the course of different types of acupuncture stimulation. We used whole head magnetoencephalography (MEG) to map S1 brain response during 15 minutes of electroacupuncture (EA) and acupressure (AP). We further assessed how brain response changed during the course of stimulation. Results Evoked brain response to EA differed from AP in its temporal dynamics by showing clear contralateral M20/M30 peaks while the latter demonstrated temporal dispersion. Both EA and AP demonstrated significantly decreased response amplitudes following five minutes of stimulation. However, the latency of these decreases were earlier in EA (~30 ms post-stimulus) than AP (> 100 ms). Time-frequency responses demonstrated early onset, event related synchronization (ERS), within the gamma band at ~70-130 ms and the theta band at ~50-200 ms post-stimulus. A prolonged event related desynchronization (ERD) of alpha and beta power occurred at ~100-300 ms post-stimulus. There was decreased beta ERD at ~100-300 ms over the course of EA, but not AP. Conclusion Both EA and AP demonstrated conditioning of SI response. In conjunction with their subcortical effects on endogenous pain regulation, these therapies show potential for affecting S1 processing and possibly altering maladaptive neuroplasticity. Thus, further investigation in neuropathic populations is needed.
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Affiliation(s)
- Thomas Witzel
- Harvard Medical School, Martinos Center for Biomedical Imaging, Charlestown, MA 02129, USA
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Telenczuk B, Baker SN, Herz AVM, Curio G. High-frequency EEG covaries with spike burst patterns detected in cortical neurons. J Neurophysiol 2011; 105:2951-9. [PMID: 21490283 DOI: 10.1152/jn.00327.2010] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Invasive microelectrode recordings measure neuronal spikes, which are commonly considered inaccessible through standard surface electroencephalogram (EEG). Yet high-frequency EEG potentials (hf-EEG, f > 400 Hz) found in somatosensory evoked potentials of primates may reflect the mean population spike responses of coactivated cortical neurons. Since cortical responses to electrical nerve stimulation vary strongly from trial to trial, we investigated whether the hf-EEG signal can also echo single-trial variability observed at the single-unit level. We recorded extracellular single-unit activity in the primary somatosensory cortex of behaving macaque monkeys and identified variable spike burst responses following peripheral stimulation. Each of these responses was classified according to the timing of its spike constituents, conforming to one of a discrete set of spike patterns. We here show that these spike patterns are accompanied by variations in the concomitant epidural hf-EEG. These variations cannot be explained by fluctuating stimulus efficacy, suggesting that they were generated within the thalamocortical network. As high-frequency EEG signals can also be reliably recorded from the scalp of human subjects, they may provide a noninvasive window on fluctuating cortical spike activity in humans.
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Affiliation(s)
- Bartosz Telenczuk
- Department of Neurology, Charité-Universitätsmedizin Berlin, Berlin, Germany.
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Huttunen J. In search of augmentation at human SI: Somatosensory cortical responses to stimulus trains and their modulation by motor activity. Brain Res 2010; 1331:74-9. [DOI: 10.1016/j.brainres.2010.03.058] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2009] [Revised: 03/15/2010] [Accepted: 03/15/2010] [Indexed: 11/28/2022]
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Very high-frequency oscillations (over 1000 Hz) of somatosensory-evoked potentials directly recorded from the human brain. J Clin Neurophysiol 2010; 26:414-21. [PMID: 19952566 DOI: 10.1097/wnp.0b013e3181c298c9] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The aims of this study were to record high-frequency oscillations (HFOs) associated with somatosensory-evoked potentials from subdural electrodes and to investigate their generators and clinical significance. Six patients who underwent long-term subdural electrode monitoring were studied. Somatosensory-evoked potentials were recorded directly from the subdural electrode after stimulation of the median nerve. Bandpass filter was 10 to 10,000 Hz for conventional somatosensory-evoked potential and 500 to 10,000 Hz for HFO. Three types of HFO were recorded. The first component was early HFO (407-926 Hz), which occurred before N20 peak. The second component was late HFO (408-909 Hz), which occurred after N20 peak. In addition, a novel component was recorded with a range from 1,235 to 2,632 Hz, and this component was termed very HFO. Early and late HFOs were recorded from relatively wide areas centering around the primary motor and primary sensory areas, whereas very HFO was localized around the primary sensory areas. In this study, at least three components of HFO could be identified. Only very HFO was localized around primary sensory areas, suggesting a possibility that very HFO may provide an effective method of identifying the central sulcus.
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Jones SR, Pritchett DL, Sikora MA, Stufflebeam SM, Hämäläinen M, Moore CI. Quantitative analysis and biophysically realistic neural modeling of the MEG mu rhythm: rhythmogenesis and modulation of sensory-evoked responses. J Neurophysiol 2009; 102:3554-72. [PMID: 19812290 DOI: 10.1152/jn.00535.2009] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Variations in cortical oscillations in the alpha (7-14 Hz) and beta (15-29 Hz) range have been correlated with attention, working memory, and stimulus detection. The mu rhythm recorded with magnetoencephalography (MEG) is a prominent oscillation generated by Rolandic cortex containing alpha and beta bands. Despite its prominence, the neural mechanisms regulating mu are unknown. We characterized the ongoing MEG mu rhythm from a localized source in the finger representation of primary somatosensory (SI) cortex. Subjects showed variation in the relative expression of mu-alpha or mu-beta, which were nonoverlapping for roughly 50% of their respective durations on single trials. To delineate the origins of this rhythm, a biophysically principled computational neural model of SI was developed, with distinct laminae, inhibitory and excitatory neurons, and feedforward (FF, representative of lemniscal thalamic drive) and feedback (FB, representative of higher-order cortical drive or input from nonlemniscal thalamic nuclei) inputs defined by the laminar location of their postsynaptic effects. The mu-alpha component was accurately modeled by rhythmic FF input at approximately 10-Hz. The mu-beta component was accurately modeled by the addition of approximately 10-Hz FB input that was nearly synchronous with the FF input. The relative dominance of these two frequencies depended on the delay between FF and FB drives, their relative input strengths, and stochastic changes in these variables. The model also reproduced key features of the impact of high prestimulus mu power on peaks in SI-evoked activity. For stimuli presented during high mu power, the model predicted enhancement in an initial evoked peak and decreased subsequent deflections. In agreement, the MEG-evoked responses showed an enhanced initial peak and a trend to smaller subsequent peaks. These data provide new information on the dynamics of the mu rhythm in humans and the model provides a novel mechanistic interpretation of this rhythm and its functional significance.
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Affiliation(s)
- Stephanie R Jones
- Massachusetts General Hospital, Athinoula A Martinos Center for Biomedical Imaging, Charlestown, MA 02129, USA.
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26
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Zhu Z, Zumer JM, Lowenthal ME, Padberg J, Recanzone GH, Krubitzer LA, Nagarajan SS, Disbrow EA. The relationship between magnetic and electrophysiological responses to complex tactile stimuli. BMC Neurosci 2009; 10:4. [PMID: 19146670 PMCID: PMC2652466 DOI: 10.1186/1471-2202-10-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Accepted: 01/15/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Magnetoencephalography (MEG) has become an increasingly popular technique for non-invasively characterizing neuromagnetic field changes in the brain at a high temporal resolution. To examine the reliability of the MEG signal, we compared magnetic and electrophysiological responses to complex natural stimuli from the same animals. We examined changes in neuromagnetic fields, local field potentials (LFP) and multi-unit activity (MUA) in macaque monkey primary somatosensory cortex that were induced by varying the rate of mechanical stimulation. Stimuli were applied to the fingertips with three inter-stimulus intervals (ISIs): 0.33s, 1s and 2s. RESULTS Signal intensity was inversely related to the rate of stimulation, but to different degrees for each measurement method. The decrease in response at higher stimulation rates was significantly greater for MUA than LFP and MEG data, while no significant difference was observed between LFP and MEG recordings. Furthermore, response latency was the shortest for MUA and the longest for MEG data. CONCLUSION The MEG signal is an accurate representation of electrophysiological responses to complex natural stimuli. Further, the intensity and latency of the MEG signal were better correlated with the LFP than MUA data suggesting that the MEG signal reflects primarily synaptic currents rather than spiking activity. These differences in latency could be attributed to differences in the extent of spatial summation and/or differential laminar sensitivity.
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Affiliation(s)
- Zhao Zhu
- Biomagnetic Imaging Laboratory, Department of Radiology, University of California San Francisco, San Francisco, CA 94143-0628, USA.
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Jaros U, Hilgenfeld B, Lau S, Curio G, Haueisen J. Nonlinear interactions of high-frequency oscillations in the human somatosensory system. Clin Neurophysiol 2008; 119:2647-57. [PMID: 18829382 DOI: 10.1016/j.clinph.2008.08.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2008] [Revised: 07/28/2008] [Accepted: 08/20/2008] [Indexed: 11/19/2022]
Abstract
OBJECTIVE The source of somatosensory evoked high-frequency activity at about 600 Hz is still not completely clear. Hence, we aimed to study the influence of double stimulation on the human somatosensory system by analyzing both the low-frequency activity and the high-frequency oscillations (HFOs) at about 600 Hz. METHODS We used median nerve stimulation at seven interstimuli intervals (ISIs) with a high time resolution between 2.4 and 4.8 ms to investigate the N15, N20 and superimposed HFOs. Simultaneously, the electroencephalogram and the magnetoencephalogram of 12 healthy participants were recorded. Subsequently, the source analysis of precortical and cortical dipoles was performed. RESULTS The difference computations of precortical dipole activation curves showed in both the low- and high-frequency range a correlation between the ISI and the latency of the second stimulus response. The cortical low-frequency response showed a similar behavior. Contrarily, in the second response of cortical HFOs this latency shift could not be confirmed. We found amplitude fluctuations that were dependent on the ISI in the low-frequency activity and the HFOs. These nonlinear interactions occurred at ISIs, which differ by one full HFO period (1.6 ms). CONCLUSIONS Low-frequency activity and HFOs originate from different generators. Precortical and cortical HFOs are independently generated. The amplitude fluctuations dependent on ISI indicate nonlinear interference between successive stimuli. SIGNIFICANCE Information processing in human somatosensory system includes nonlinearity.
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Affiliation(s)
- U Jaros
- Biomagnetic Center, Department of Neurology, University Hospital Jena, Erlanger Allee 101, 07747 Jena, Germany
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Witzel T, Lin FH, Rosen BR, Wald LL. Stimulus-induced Rotary Saturation (SIRS): a potential method for the detection of neuronal currents with MRI. Neuroimage 2008; 42:1357-65. [PMID: 18684643 DOI: 10.1016/j.neuroimage.2008.05.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2007] [Revised: 04/15/2008] [Accepted: 05/01/2008] [Indexed: 10/22/2022] Open
Abstract
Neuronal currents produce local transient and oscillatory magnetic fields that can be readily detected by MEG. Previous work attempting to detect these magnetic fields with MR focused on detecting local phase shifts and dephasing in T(2) or T(2)-weighted images. For temporally biphasic and multi-phasic local currents the sensitivity of these methods can be reduced through the cancellation of the accrued phase induced by positive and negative episodes of the neuronal current. The magnitude of the phase shift is also dependent on the distribution of the current within the voxel. Since spins on one side of a current source develop an opposite phase shift relative to those on the other side, there is likely to be significant cancellation within the voxel. We introduce a potential method for detecting neuronal currents though their resonant T(1rho) saturation during a spin-lock preparation period. The method is insensitive to the temporal and spatial cancellation effects since it utilizes the multi-phasic nature of the neuronal currents and thus is not sensitive to the sign of the local field. To produce a T(1)(rho) reduction, the Larmor frequency in the rotating frame, which is set by gammaB(1lock) (typically 20 Hz-5 kHz), must match the major frequency components of the stimulus-induced neuronal currents. We validate the method in MRI phantom studies. The rotary saturation spectra showed a sharp resonance when a current dipole within the phantom was driven at the Larmor frequency in the rotating frame. A 7 min block-design experiment was found to be sensitive to a current dipole strength of 56 nAm, an approximate magnetic field of 1 nT at 1.5 mm from the dipole. This dipole moment is similar to that seen using the phase shift method in a similar experimental setup by Konn et al. [Konn, D., Gowland, P., Bowtell, R., 2003. MRI detection of weak magnetic fields due to an extended current dipole in a conducting sphere: a model for direct detection of neuronal currents in the brain. Magn. Reson. Med. 50, 40-49], but is potentially less encumbered by temporal and spatial cancellation effects.
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Affiliation(s)
- Thomas Witzel
- Speech and Hearing Bioscience and Technology Program, Harvard-MIT Division of Health Sciences and Technology, USA.
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29
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Jacobs J, LeVan P, Chander R, Hall J, Dubeau F, Gotman J. Interictal high-frequency oscillations (80-500 Hz) are an indicator of seizure onset areas independent of spikes in the human epileptic brain. Epilepsia 2008; 49:1893-907. [PMID: 18479382 DOI: 10.1111/j.1528-1167.2008.01656.x] [Citation(s) in RCA: 413] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE High-frequency oscillations (HFOs) known as ripples (80-250 Hz) and fast ripples (250-500 Hz) can be recorded from macroelectrodes inserted in patients with intractable focal epilepsy. They are most likely linked to epileptogenesis and have been found in the seizure onset zone (SOZ) of human ictal and interictal recordings. HFOs occur frequently at the time of interictal spikes, but were also found independently. This study analyses the relationship between spikes and HFOs and the occurrence of HFOs in nonspiking channels. METHODS Intracerebral EEGs of 10 patients with intractable focal epilepsy were studied using macroelectrodes. Rates of HFOs within and outside spikes, the overlap between events, event durations, and the percentage of spikes carrying HFOs were calculated and compared according to anatomical localization, spiking activity, and relationship to the SOZ. RESULTS HFOs were found in all patients, significantly more within mesial temporal lobe structures than in neocortex. HFOs could be seen in spiking as well as nonspiking channels in all structures. Rates and durations of HFOs were significantly higher in the SOZ than outside. It was possible to establish a rate of HFOs to identify the SOZ with better sensitivity and specificity than with the rate of spikes. DISCUSSION HFOs occurred to a large extent independently of spikes. They are most frequent in mesial temporal structures. They are prominent in the SOZ and provide additional information on epileptogenicity independently of spikes. It was possible to identify the SOZ with a high specificity by looking at only 10 min of HFO activity.
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Affiliation(s)
- Julia Jacobs
- Montreal Neurological Institute and Hospital, Montreal, Canada.
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Huttunen J, Pekkonen E, Kivisaari R, Autti T, Kähkönen S. Modulation of somatosensory evoked fields from SI and SII by acute GABA A -agonism and paired-pulse stimulation. Neuroimage 2008; 40:427-434. [DOI: 10.1016/j.neuroimage.2007.12.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 09/24/2007] [Accepted: 12/17/2007] [Indexed: 11/15/2022] Open
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Jones SR, Pritchett DL, Stufflebeam SM, Hämäläinen M, Moore CI. Neural correlates of tactile detection: a combined magnetoencephalography and biophysically based computational modeling study. J Neurosci 2007; 27:10751-64. [PMID: 17913909 PMCID: PMC2867095 DOI: 10.1523/jneurosci.0482-07.2007] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Revised: 08/16/2007] [Accepted: 08/19/2007] [Indexed: 11/21/2022] Open
Abstract
Previous reports conflict as to the role of primary somatosensory neocortex (SI) in tactile detection. We addressed this question in normal human subjects using whole-head magnetoencephalography (MEG) recording. We found that the evoked signal (0-175 ms) showed a prominent equivalent current dipole that localized to the anterior bank of the postcentral gyrus, area 3b of SI. The magnitude and timing of peaks in the SI waveform were stimulus amplitude dependent and predicted perception beginning at approximately 70 ms after stimulus. To make a direct and principled connection between the SI waveform and underlying neural dynamics, we developed a biophysically realistic computational SI model that contained excitatory and inhibitory neurons in supragranular and infragranular layers. The SI evoked response was successfully reproduced from the intracellular currents in pyramidal neurons driven by a sequence of lamina-specific excitatory input, consisting of output from the granular layer (approximately 25 ms), exogenous input to the supragranular layers (approximately 70 ms), and a second wave of granular output (approximately 135 ms). The model also predicted that SI correlates of perception reflect stronger and shorter-latency supragranular and late granular drive during perceived trials. These findings strongly support the view that signatures of tactile detection are present in human SI and are mediated by local neural dynamics induced by lamina-specific synaptic drive. Furthermore, our model provides a biophysically realistic solution to the MEG signal and can predict the electrophysiological correlates of human perception.
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Affiliation(s)
- Stephanie R Jones
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
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Urrestarazu E, Jirsch JD, LeVan P, Hall J, Avoli M, Dubeau F, Gotman J. High-frequency intracerebral EEG activity (100-500 Hz) following interictal spikes. Epilepsia 2006; 47:1465-76. [PMID: 16981862 DOI: 10.1111/j.1528-1167.2006.00618.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
PURPOSE High-frequency activity has been recorded with intracerebral microelectrodes in epileptic patients and related to seizure genesis. Our goal was to analyze high-frequency activity recorded with electroencephalograph (EEG) macroelectrodes during the slow wave immediately following interictal spikes, given the potential importance of this presumed hyperpolarization in transforming spikes into seizures. METHODS Depth electrode EEG recordings from 10 patients with intractable focal epilepsy were low-pass filtered at 500 Hz and sampled at 2,000 Hz. Spikes were categorized according to localization and morphology. Segments of 256 ms were selected immediately following (postspike), and 2 s before each spike (baseline). Power was estimated in subgamma (0-40 Hz), gamma (40-100 Hz), high frequency (100-200 Hz), and very high frequency (250-500 Hz) bands. RESULTS Changes in power above 100 Hz were seen in 22 of 29 spike categories, consisting primarily of a widespread decrease in frequencies above 100 Hz. This decrease became spatially more restricted as frequencies increased, and coincided with the localization of largest spikes for the highest frequencies. High-frequency power decreases were prominent in the hippocampus but less common in amygdala and neocortex. High-frequency power increases were observed in the amygdala. CONCLUSIONS Thus high-frequency EEG activity can be recorded with macroelectrodes in humans and may provide insights on neuronal mechanisms related to human epilepsy. This activity undergoes consistent modifications after EEG spikes. We propose that the reduction in high frequencies reflects a postspike depression in neuronal activity that is more pronounced in the region of spike generation. This depression is almost always seen in hippocampus but less in amygdala.
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Affiliation(s)
- Elena Urrestarazu
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
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Huttunen J, Komssi S, Lauronen L. Spatial dynamics of population activities at S1 after median and ulnar nerve stimulation revisited: An MEG study. Neuroimage 2006; 32:1024-31. [PMID: 16777434 DOI: 10.1016/j.neuroimage.2006.04.196] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2005] [Revised: 02/28/2006] [Accepted: 04/18/2006] [Indexed: 11/29/2022] Open
Abstract
In a number of studies, magnetoencephalography (MEG) has been successfully employed in localizing cortical neural population activities after stimulation of peripheral nerves. Little attention has been paid, however, to the spatiotemporal dynamics of these activations within the primary somatosensory cortex (SI). Here we report on the activation sequence at the right SI after left median and ulnar nerve stimulation. The results show that at least three macroscopically separable sources within or near SI are activated within 100 ms after the stimulus, corresponding to the somatosensory evoked field (SEF) deflections N20m, P35m and P60m. As P60m was localized significantly more posteriorly and also tended to be deeper than the two earlier deflections, its underlying source may be more extensive than during N20m and P35m, and it may get contribution from the postcentral gyrus and sulcus, possibly Brodmann areas 1 and 2. The source separation between the neural populations activated by the 2 nerves was 12 mm during N20m, 6 mm during P35m and 4 mm during P60m. Thus, at longer latencies, the centers of gravity of the activations were closer to each other for the 2 nerves. We argue that this reflects spreading of the activation with time from the site of initial excitation to encompass larger and more overlapping neural populations at longer latencies.
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Affiliation(s)
- Juha Huttunen
- BioMag Laboratory, Engineering Centre, Helsinki University Central Hospital, FIN-00029 Helsinki, Finland.
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Murakami S, Okada Y. Contributions of principal neocortical neurons to magnetoencephalography and electroencephalography signals. J Physiol 2006; 575:925-36. [PMID: 16613883 PMCID: PMC1995687 DOI: 10.1113/jphysiol.2006.105379] [Citation(s) in RCA: 209] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
A realistically shaped three-dimensional single-neuron model was constructed for each of four principal cell types in the neocortex in order to infer their contributions to magnetoencephalography (MEG) and electroencephalography (EEG) signals. For each cell, the soma was stimulated and the resulting intracellular current was used to compute the current dipole Q for the whole cell or separately for the apical and basal dendrites. The magnitude of Q is proportional to the magnetic field and electrical potential far from the neuron. A train of spikes and depolarization shift in an intracellular burst discharge were seen as spikes and an envelope in Q for the layer V and layer II/III pyramidal cells. The stellate cells lacked the envelope. As expected, the pyramidal cells produced a stronger Q than the stellate cells. The spikes produced by the layer V pyramidal cells (n = 4) varied between -0.78 and 2.97 pA m with the majority of the cells showing a current toward the pia (defined as positive). The basal dendrites, however, produced considerable spike currents. The magnitude and direction of dipole moment are in agreement with the distribution of the dendrites. The spikes in Q for the layer V pyramidal cells were produced by the transient sodium conductance and potassium conductance of delayed rectifier type; the conductances distributed along the dendrites were capable of generating spike propagation, which was seen in Q as the tail of a triphasic wave lasting several milliseconds. The envelope was similar in magnitude (-0.41 to -0.90 pA m) across the four layer V pyramidal cells. The spike and envelope for the layer II/III pyramidal cell were 0.47 and -0.29 pA m, respectively; these values agreed well with empirical and theoretical estimates for guinea pig CA3 pyramidal cells. Spikes were stronger for the layer IV spiny stellate (0.27 pA m) than the layer III aspiny stellate cell (0.06 pA m) along their best orientations. The spikes may thus be stronger than has been previously thought. The Q for a population of stellate cells may be weaker than a linear sum of their individual Q values due to their variable dendritic geometry. The burst discharge by pyramidal cells may be detectable with MEG and EEG when 10 000-50 000 cells are synchronously active.
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Affiliation(s)
- Shingo Murakami
- Division of Molecular and Cellular Pharmacology, Department of Pharmacology, Graduate School of Medicine, Osaka University, 2-2 Yamada-oka, Suita, Osaka 565-0871 Japan.
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Wang Y, Hosler G, Zhang T, Okada Y. Effects of temporary bilateral ligation of the internal carotid arteries on the low- and high-frequency somatic evoked potentials in the swine. Clin Neurophysiol 2005; 116:2420-8. [PMID: 16125462 DOI: 10.1016/j.clinph.2005.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Revised: 06/16/2005] [Accepted: 07/03/2005] [Indexed: 11/19/2022]
Abstract
OBJECTIVE We studied effects of a temporary bilateral ligation of the internal carotid arteries on the subcortical and cortical structures of the somatosensory system by examining the thalamic input and postsynaptic cortical responses contained in the somatic evoked potentials (SEPs) recorded from the primary somatosensory cortex (SI) of the juvenile piglets in vivo. We predicted that the ligation should differentially affect these structures due to differences in blood supply. METHODS The SEPs between 1 and 3000 Hz were measured in the SI cortex with a multichannel electrode array before, during and after a 20 min bilateral ligation of the internal carotid arteries in the swine under a barbiturate anesthesia. RESULTS The ligation differentially affected the thalamic input and the cortical responses contained in the high-frequency signals (HFSs) between 400 and 2000 Hz. The amplitude of the thalamic input did not change, but the amplitudes of the cortical HFS postsynaptic to the thalamic inputs decreased immediately after start of ligation, recovering over the next 30-90 min. The latency showed a small, but significant increase for several minutes after the start of ligation for both the thalamic input and cortical responses. The ligation increased the latency and reduced the amplitude of the peak of the first cortical response in the wideband SEP corresponding to human N20. CONCLUSIONS The HFS is useful for distinguishing selective effects of the temporary ligation on the subcortical and cortical structures of the somatosensory system. Since the porcine N20 starts after the presynaptic HFS, it was not useful in differentiating thalamic and cortical effects. SIGNIFICANCE The HFS may open a new window in studying the cortical physiology in humans.
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Affiliation(s)
- Yaozhi Wang
- Department of Neurology and Biomedical Research and Integrative NeuroImaging (BRaIN Imaging) Center, University of New Mexico School of Medicine, Albuquerque, NM 87131, USA
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Okada Y, Ikeda I, Zhang T, Wang Y. High-frequency signals (> 400 hz): a new window in electrophysiological analysis of the somatosensory system. Clin EEG Neurosci 2005; 36:285-92. [PMID: 16296446 DOI: 10.1177/155005940503600408] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
High-frequency signals (HFSs) between 400-1500 Hz in Magnetoencephalography (MEG) and Electroencephalography (EEG) provide a new window in electrophysiological analysis of the somatosensory system in humans and in other animals. The HFS in the primary somatosensory (SI) cortex precedes the conventional N20. In the swine model, they appear to be due to spiking in thalamocortical axonal terminals and in the soma and dendrites of cortical neurons. These spiking activities seem to activate slower conductances in the pyramidal cells in layers II-III and V, which give rise to N20. The HFS monitoring may be useful for separately evaluating the electrophysiology of the subcortical and cortical components of the somatosensory pathway.
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Affiliation(s)
- Y Okada
- Department of Neurology, University of New Mexico School of Medicine, Albuquerque, New Mexico, 87131-0001, USA.
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Abstract
Spontaneous and stimulus-induced oscillatory EEG activities range over a wide scope of frequencies from 1 Hz to 1 kHz. In the ultrafast domain, trains of 5-10 micropotentials are superimposed to primary thalamic and cortical components in somtosensory evoked potentials (SEP) as brief bursts of 1000 Hz and 600 Hz, respectively. Over the last years, hypotheses on generators and functions of this frequency-edge of population activity have been elaborated in numerous studies. Here, the relevant findings and ideas were surveyed from the body of literature. Special emphasis was paid to the anatomical and cellular origin of burst SEP, their assumed impact on somatosensory coding and perspectives for scientific as well as clinical applications.
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Affiliation(s)
- Fabian Klostermann
- Charité-Universitätsmedizin Berlin, CBF, Dept. ol Neurology, Hindenburgdamm 30, 12200 Berlin, Germany.
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