Intracranial Electrophysiology Research Articles

Action control related local field potentials in the human pedunculopontine nuclei: a single case report

Event Abstract Back to Event Action control related local field potentials in the human pedunculopontine nuclei: a single case report Marcus Heldmann1*, Tino Zaehle2, Imke Galazky3, Thomas Münte1, Jürgen Voges4, Hans-Jochen Heinze3 and Hermann Hinrichs3 1 Dep. Neurology, University Medical Center SH, Germany 2 German Centre for Neurodegenerative Diseases (DZNE) Magdeburg, Germany 3 University Department of Neurology, Magdeburg, Germany 4 Department of Stereotactic Neurosurgery, Germany The pedunculopontine nucleus (PPN) is a rostral midbrain structure and an essential part of the reticular activation system and the mesencephalic locomotor region. Anatomically, the PPN is characterized by its reciprocal cholinergic and non-cholinergic connections to the basal ganglia, the thalamus and the spinal cord. It is known from the animal literature that the PPN is not only involved in sleep behavior and the control of movement, but also supports cognitive functions like attention, reward processing and learning. The PPN has recently been identified as a target for deep brain stimulation (DBS) to treat Parkinson Disease and related movement disorders such as progressive supranuclear palsy (PSP) in particular for freezing of gait and postural instability. Thus, the impact of DBS in the PPN on executive functions and the control of motor behavior in humans can be investigated. First behavioral studies reported faster reaction times and improved executive functions under active DBS, indicating an involvement of the PPN in these functions in humans. In the present single case report we recorded local field potentials from the PPN in a 71 years old PSP patient, while he performed two simple motor (tapping/task-switching) paradigms. Results clearly demonstrate an association of intracranially recoded local field potentials in the (left) PPN and the given feedback information that indicated to switch or not to switch the task set. We will discuss this finding as first direct evidence for an involvement of the human PPN in action monitoring mechanisms. Keywords: Intra-cranial Electrophysiology, PPN Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Heldmann M, Zaehle T, Galazky I, Münte T, Voges J, Heinze H and Hinrichs H (2011). Action control related local field potentials in the human pedunculopontine nuclei: a single case report. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00072 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 16 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Marcus Heldmann, Dep. Neurology, University Medical Center SH, Lübeck, Germany, marcus.heldmann@neuro.uni-luebeck.de Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Marcus Heldmann Tino Zaehle Imke Galazky Thomas Münte Jürgen Voges Hans-Jochen Heinze Hermann Hinrichs Google Marcus Heldmann Tino Zaehle Imke Galazky Thomas Münte Jürgen Voges Hans-Jochen Heinze Hermann Hinrichs Google Scholar Marcus Heldmann Tino Zaehle Imke Galazky Thomas Münte Jürgen Voges Hans-Jochen Heinze Hermann Hinrichs PubMed Marcus Heldmann Tino Zaehle Imke Galazky Thomas Münte Jürgen Voges Hans-Jochen Heinze Hermann Hinrichs Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Timing and amplitude of gamma-band deactivation in default-mode network is correlated with behavior

Event Abstract Back to Event Timing and amplitude of gamma-band deactivation in default-mode network is correlated with behavior Tomas Ossandon1*, Karim Jerbi1, Juan R. Vidal1, Dimitri Bayle1, Olivier Bertrand11, Philippe Kahane2 and Jean-Philippe Lachaux1 1 Lyon Neuroscience Research Center, France 2 Neurology Department, Grenoble University Hospital, France Task-related deactivations, described in the default mode network (DMN) literature, have been predominantly reported with functional imaging studies (Raichle et al., 2001). Therefore, the electrophysiological correlates and the fine-scale temporal dynamics of this phenomenon are still poorly understood. Given that recent animal studies as well as recent findings in humans (Niessing et al., 2005) suggest correlations between the BOLD signal and gamma-band activity, we posit that gamma deactivation may provide an electrophysiological correlate of the DMN. To test this hypothesis we examine the spatial and temporal pattern of high gamma (60-140 Hz) power suppression using intracranial EEG recordings simultaneously from widespread cortical structures in subjects performing a visual search task. We used direct recordings of neural activity in 15 epileptic patients implanted with depth electrodes for therapeutic purposes. The subjects performed a visual search paradigm with variable levels of task difficulty. We use time-frequency analysis to assess the presence, duration and intensity of gamma band power induced by the display of the search array. We found that all DMN areas displayed transient suppressions of gamma (60-140 Hz) power during task performance and, critically, the duration and extent of this broadband suppression were correlated with task complexity and subject performance. Furthermore, trial-by-trial correlations revealed that spatially distributed gamma activations and deactivations formed distinct anticorrelated networks. These findings facilitate our understanding of the relationship between electrophysiology and neuroimaging studies in humans and indicate that neural deactivations encode the duration and efficiency of our engagement with the external world. Funding: Fondation pour la Recherche Medicale (FRM) and BrainSync FP7 European Project (Grant HEALTH-F2-2008-200728). Keywords: gamma band, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Ossandon T, Jerbi K, Vidal JR, Bayle D, Bertrand1 O, Kahane P and Lachaux J (2011). Timing and amplitude of gamma-band deactivation in default-mode network is correlated with behavior. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00065 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Tomas Ossandon, Lyon Neuroscience Research Center, Lyon, France, tossandon@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Tomas Ossandon Karim Jerbi Juan R Vidal Dimitri Bayle Olivier Bertrand1 Philippe Kahane Jean-Philippe Lachaux Google Tomas Ossandon Karim Jerbi Juan R Vidal Dimitri Bayle Olivier Bertrand1 Philippe Kahane Jean-Philippe Lachaux Google Scholar Tomas Ossandon Karim Jerbi Juan R Vidal Dimitri Bayle Olivier Bertrand1 Philippe Kahane Jean-Philippe Lachaux PubMed Tomas Ossandon Karim Jerbi Juan R Vidal Dimitri Bayle Olivier Bertrand1 Philippe Kahane Jean-Philippe Lachaux Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

The neural facebook": exemplar selectivity in human face-selective areas revealed through intracranial EEG recordings

Event Abstract Back to Event The neural facebook": exemplar selectivity in human face-selective areas revealed through intracranial EEG recordings Ido Davidesco1*, Stephan Bickel2, Elana Zion-Golumbic3, Michal Harel4, Charles E. Schroeder3, Ashesh D. Mehta2 and Rafael Malach4 1 Hebrew University of Jerusalem, Israel 2 Long Island Jewish Medical Center, New Hyde Park, United States 3 Columbia University College of Physicians and Surgeons & Nathan Kline Institute, United States 4 Weizmann Institute of Science, Israel Humans have a remarkable ability to distinguish between different faces, familiar and unfamiliar alike. However, fMRI studies of high-order visual cortex generally show only category selectivity (e.g. preference for faces), not selectivity for individual exemplars from the same category. Exemplar selectivity has been inferred so far only indirectly from adaptation effects. Here, we examined this issue directly, using intracranial EEG recordings (iEEG) in epilepsy patients monitored for presurgical evaluation. The patients were presented with images of faces, houses, objects and patterns. Each individual image was repeated 6 times throughout the experiment. Our results show that in addition to category selectivity, high-order visual regions, especially face-related areas (e.g. Fusiform face area, FFA), exhibit exemplar selectivity. Comparing the Gamma band responses to optimal and non-optimal stimuli from the same category showed a highly significant decline to about 30%. This effect was highly reproducible within each patient and across patients. Interestingly, the optimal face exemplars, which yielded the strongest response, were different in each electrode, even when the electrodes were adjacent. Control experiments were performed in order to verify that this effect can not be explained by low level differences between the exemplars. These results demonstrate clear exemplar selectivity in human high-order visual areas. Furthermore, the high selectivity evident in the mass local field potentials - likely reflecting activity in thousands of neurons - points to the clustering of these neurons in exemplar-selective cortical patches or columns. Such exemplar selectivity provides the neuronal substrate for individual identification in human observers. Funding: Supported by ISF, Bikura, and Mark Scher’s estate grants to RM. Keywords: EEG, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Davidesco I, Bickel S, Zion-Golumbic E, Harel M, Schroeder CE, Mehta AD and Malach R (2011). The neural facebook": exemplar selectivity in human face-selective areas revealed through intracranial EEG recordings. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00071 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 16 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Ido Davidesco, Hebrew University of Jerusalem, Jerusalem, Israel, idd@netvision.net.il Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ido Davidesco Stephan Bickel Elana Zion-Golumbic Michal Harel Charles E Schroeder Ashesh D Mehta Rafael Malach Google Ido Davidesco Stephan Bickel Elana Zion-Golumbic Michal Harel Charles E Schroeder Ashesh D Mehta Rafael Malach Google Scholar Ido Davidesco Stephan Bickel Elana Zion-Golumbic Michal Harel Charles E Schroeder Ashesh D Mehta Rafael Malach PubMed Ido Davidesco Stephan Bickel Elana Zion-Golumbic Michal Harel Charles E Schroeder Ashesh D Mehta Rafael Malach Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Two distinct theta rhythms could underlie functional asymmetry of auditory cortices

Event Abstract Back to Event Two distinct theta rhythms could underlie functional asymmetry of auditory cortices Benjamin Morillon1*, Catherine Liegeois-Chauvel2, Luc Arnal3 and Anne-Lise Giraud1 1 Ecole Normale Supérieure, France 2 Université de la Méditerranée, France 3 New York University, United States Poeppel (2003) proposed that left hemispheric dominance in speech processing relies on asymmetric sampling of auditory information. Cortical oscillations in the gamma (~40Hz) and low-theta (~5 Hz) range could be instrumental to this purpose, underpinning phonemic and supra-segmental parsing in left and right auditory cortices, respectively. Yet, whether and how left-hemispheric information sampled at phonemic timescale is re-concatenated into syllabic frames is unaddressed by the theory. Here we present evidence from local field potentials data from an epileptic patient implanted bilaterally in primary (PAC) and secondary (SAC) auditory cortices that two distinct theta ranges operate in right and left auditory cortices. During periods of silence, we observed a peak of energy at 5 Hz in the right auditory cortex and at 8 Hz in the left one. These effects were maximal in SAC. This asymmetric background low and high theta activity was boosted by the presentation of transient tones and syllables. The 8 Hz response in left auditory cortex was accompanied with a low-gamma transient response. Finally, sentences elicited sustained responses in the theta range, with the same 5/8 Hz asymmetrical pattern. We thus confirm that low-theta rhythm (5 Hz) is right-dominant both at rest (Giraud et al., 2007) and during speech processing (Abrams et al., 2008), but additionally show the presence of a parallel high-theta rhythm (8 Hz) in left auditory cortex. Its predominance in left SAC relative to PAC, where gamma rhythm is more strongly expressed (Morillon et al., 2010; Giraud et al., 2007) could reflect that it integrates information from the latter into syllabic frames to guide further processing stages. The role of this specific rhythm (Mo et al., 2011) needs to be further explored. Keywords: cortical oscillations, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Morillon B, Liegeois-Chauvel C, Arnal L and Giraud A (2011). Two distinct theta rhythms could underlie functional asymmetry of auditory cortices. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00063 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Benjamin Morillon, Ecole Normale Supérieure, Paris, France, bnmorillon@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud Google Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud Google Scholar Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud PubMed Benjamin Morillon Catherine Liegeois-Chauvel Luc Arnal Anne-Lise Giraud Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Reading the mind's eye: online detection of visual imagery in the inferior temporal lobe, physiology and BCI applications

Event Abstract Back to Event Reading the mind's eye: online detection of visual imagery in the inferior temporal lobe, physiology and BCI applications Carlos M. Hamame1*, Juan R. Vidal1, Tomas Ossandon1, Karim Jerbi1, Sarang S. Dalal1, Lorella Minnotti2, Olivier Bertrand1, Philippe Kahane2 and Jean-Philippe Lachaux1 1 Brain Dynamics and Cognition, Lyon Neuroscience Research Center, INSERM U1028, France 2 Neurology Department, Grenoble University Hospital, INSERM U836, Grenoble Neuroscience Institute, University Joseph Fourier, Spain Brain-computer interface (BCI) technology can offer patients with severe motor impairments an opportunity to improve the communication and interaction with their environment. The voluntary control of attention to stabilize a given mental process is the most effective cognitive strategy for operating BCIs. Here we tested the potential of visual imagery as a way to move forward novel BCI systems that could convert 'visual thoughts into actions'. We analyzed intracerebral EEG recordings from the left inferior temporal lobe of an epileptic patient during working memory tasks and mental imagery. We found that high frequency gamma-band activity [50 Hz-150 Hz] in the inferior temporal gyrus increased with memory load only during visuo-spatial, but not verbal, working memory. Using a real-time set-up to measure and visualize gamma-band activity online- BrainTV- we found a systematic activity increase in that site when the patient was thinking about a letter (visual imagery), but no when she was perceiving letters (visual stimulation). In contrast, only 7 mm more medially, neurons located in the fusiform gyrus exhibited a complete opposite pattern, responding to visually presented letters, but no during imagery or visuo-spatial working memory maintenance. We conclude that neural networks supporting imagination of a visual element are not necessarily the same underlying perception of that element. Additionally, we present evidences that gamma-band activity in the inferior temporal lobe can be used for novel BCIs controlled by visual thoughts and also as a direct measure of the efficiency of top-down attention control over visual areas. Keywords: EEG, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Hamame CM, Vidal JR, Ossandon T, Jerbi K, Dalal SS, Minnotti L, Bertrand O, Kahane P and Lachaux J (2011). Reading the mind's eye: online detection of visual imagery in the inferior temporal lobe, physiology and BCI applications. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00057 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Carlos M Hamame, Brain Dynamics and Cognition, Lyon Neuroscience Research Center, INSERM U1028, Lyon, France, carlos.hamame@inserm.fr Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Carlos M Hamame Juan R Vidal Tomas Ossandon Karim Jerbi Sarang S Dalal Lorella Minnotti Olivier Bertrand Philippe Kahane Jean-Philippe Lachaux Google Carlos M Hamame Juan R Vidal Tomas Ossandon Karim Jerbi Sarang S Dalal Lorella Minnotti Olivier Bertrand Philippe Kahane Jean-Philippe Lachaux Google Scholar Carlos M Hamame Juan R Vidal Tomas Ossandon Karim Jerbi Sarang S Dalal Lorella Minnotti Olivier Bertrand Philippe Kahane Jean-Philippe Lachaux PubMed Carlos M Hamame Juan R Vidal Tomas Ossandon Karim Jerbi Sarang S Dalal Lorella Minnotti Olivier Bertrand Philippe Kahane Jean-Philippe Lachaux Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Face value: emotion categorization augments gamma oscillations in the prefrontal and inferior parietal cortex

Event Abstract Back to Event Face value: emotion categorization augments gamma oscillations in the prefrontal and inferior parietal cortex Avgusta Shestyuk1*, Heidi Kirsch2, Edward Chang2, Nicholas M. Barbaro2, Nathan E. Crone3 and Robert T. Knight1 1 Helen Wills Neuroscience Institute, University of California Berkeley, United States 2 University of California, San Francisco, United States 3 Johns Hopkins University, United States Activity in the fronto-pariatal cortical regions in response to facial stimuli has been observed in several studies. However, it remains unclear whether this activation is automatic or can be modulated by depth of processing and emotional properties of facial expressions. To examine this question, intracranial electrocorticogram (ECoG) signals were recorded in 4 subjects with intractable epilepsy. Participants completed two tasks with the same stimulus set: an explicit emotional categorization (i.e, discriminating between angry and neutral facial expressions), and a perceptual gender categorization task (i.e., discriminating between male and female faces). The task order was counterbalanced, and each stimulus was presented for 300 ms. Increases in spectral power in the gamma range (70-150 Hz) were used to index functional activation of the underlying cortex. Subjects found the perceptual task easier and more automatic than the emotional categorization task, as evidenced by shorter reaction times and fewer errors. There were no differences in reaction times between angry and neutral faces. Electrodes positioned over the left inferior-middle frontal and inferior parietal cortices recorded an increase in gamma power during the explicit emotional categorization relative to perceptual categorization (p < .01). Angry faces categorized based on emotion elicited greater gamma responses than neutral faces (p < .01). When present, increased gamma oscillations in the prefrontal cortex were time-locked (~250 ms) to stimulus presentation and lasted until subjects made the response. These results highlight the role of the fronto-temporal brain areas (also implicated in attention, working memory, and mimicking) in processing of emotional facial information and response selection. Funding: Supported by NIH Grants: MH075317, NS21135, NS065120. Keywords: gamma band, Intra-cranial Electrophysiology Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Abstracts Citation: Shestyuk A, Kirsch H, Chang E, Barbaro NM, Crone NE and Knight RT (2011). Face value: emotion categorization augments gamma oscillations in the prefrontal and inferior parietal cortex. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00066 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 15 Nov 2011; Published Online: 25 Nov 2011. * Correspondence: Dr. Avgusta Shestyuk, Helen Wills Neuroscience Institute, University of California Berkeley, Berkeley, United States, ashestyuk@berkeley.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Avgusta Shestyuk Heidi Kirsch Edward Chang Nicholas M Barbaro Nathan E Crone Robert T Knight Google Avgusta Shestyuk Heidi Kirsch Edward Chang Nicholas M Barbaro Nathan E Crone Robert T Knight Google Scholar Avgusta Shestyuk Heidi Kirsch Edward Chang Nicholas M Barbaro Nathan E Crone Robert T Knight PubMed Avgusta Shestyuk Heidi Kirsch Edward Chang Nicholas M Barbaro Nathan E Crone Robert T Knight Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Hemicraniectomy: A New Model for Human Electrophysiology with High Spatio-temporal Resolution

Human electrophysiological research is generally restricted to scalp EEG, magneto-encephalography, and intracranial electrophysiology. Here we examine a unique patient cohort that has undergone decompressive hemicraniectomy, a surgical procedure wherein a portion of the calvaria is removed for several months during which time the scalp overlies the brain without intervening bone. We quantify the differences in signals between electrodes over areas with no underlying skull and scalp EEG electrodes over the intact skull in the same subjects. Signals over the hemicraniectomy have enhanced amplitude and greater task-related power at higher frequencies (60-115 Hz) compared with signals over skull. We also provide evidence of a metric for trial-by-trial EMG/EEG coupling that is effective over the hemicraniectomy but not intact skull at frequencies >60 Hz. Taken together, these results provide evidence that the hemicraniectomy model provides a means for studying neural dynamics in humans with enhanced spatial and temporal resolution.

Relationship between neural and hemodynamic signals during spontaneous activity studied with temporal kernel CCA

Functional magnetic resonance imaging (fMRI) based on the so-called blood oxygen level-dependent (BOLD) contrast is a powerful tool for studying brain function not only locally but also on the large scale. Most studies assume a simple relationship between neural and BOLD activity, in spite of the fact that it is important to elucidate how the “when” and “what” components of neural activity are correlated to the “where” of fMRI data. Here we conducted simultaneous recordings of neural and BOLD signal fluctuations in primary visual (V1) cortex of anesthetized monkeys. We explored the neurovascular relationship during periods of spontaneous activity by using temporal kernel canonical correlation analysis (tkCCA). tkCCA is a multivariate method that can take into account any features in the signals that univariate analysis cannot. The method detects filters in voxel space (for fMRI data) and in frequency–time space (for neural data) that maximize the neurovascular correlation without any assumption of a hemodynamic response function (HRF). Our results showed a positive neurovascular coupling with a lag of 4–5 s and a larger contribution from local field potentials (LFPs) in the γ range than from low-frequency LFPs or spiking activity. The method also detected a higher correlation around the recording site in the concurrent spatial map, even though the pattern covered most of the occipital part of V1. These results are consistent with those of previous studies and represent the first multivariate analysis of intracranial electrophysiology and high-resolution fMRI.

“All that Spikes is Not Fits,” Mistaking the Woods for the Trees: The Interictal Spikes—An “EEG Chameleon” in the Interface Disorders of Brain and Mind: A Critical Review

Recent research into mammalian cortical neurophysiology, after 6 decades of Berger's seminal work on electroencephalography, has shifted the older concept of interictal epileptiform activity (IEA) away from that of a mere electrographic graphoelement of relevance to diagnostic implications in epilepsy. Instead, accumulating information has stressed the neuropsychological implications, cognitive and/or behavioral consequence of these electrophysiological events, which are the phenotypic expression of aberrations of actual biophysical cellular function. We feel that this review is germane to neuropsychiatry, however, a rather neglected area of research. There is a great scope for brain-behavior-EEG research in the future that can be complimented by other techniques of "neurobehavioral electrophysiology". This review does not address the "pearls, perils and pitfalls" in the use of EEG in epilepsy, but critically and systematically reappraises the published electroencephalographic correlates of human behavior. We reiterate that epileptiform and other paroxysmal EEG dysrhythmias unrelated to clinical seizures do have neuropsychological, cognitive and/or behavioral implications as seen in the various neuropsychiatric and neurobehavioral disorders discussed in this article. IEA and EEG dysrhythmias should neither be ignored as irrelevant nor automatically attributed to epilepsy. The relevance of these EEG aberrations in the disorders of the brain-mind interface extend beyond epilepsy, and may be an electrophysiological endophenotype of aberrant neuronal behavior indicative of underlying morpho-functional brain abnormalities. Magnetoencephalography (MEG), data fusion models (EEG-fMRI-BOLD), transcranial magnetic stimulation (TMS), evoked potentials (EP); intracranial electrophysiology, and EEG neurofeedback complemented by current functional neuroimaging techniques (fMRI and PET) would certainly help in further understanding the broader relationship between brain and behavior.

Functional Reactivity of Cerebral Capillaries

The spatiotemporal evolution of cerebral microcirculatory adjustments to functional brain stimulation is the fundamental determinant of the functional specificity of hemodynamically weighted neuroimaging signals. Very little data, however, exist on the functional reactivity of capillaries, the vessels most proximal to the activated neuronal population. Here, we used two-photon laser scanning microscopy, in combination with intracranial electrophysiology and intravital video microscopy, to explore the changes in cortical hemodynamics, at the level of individual capillaries, in response to steady-state forepaw stimulation in an anesthetized rodent model. Overall, the microcirculatory response to functional stimulation was characterized by a pronounced decrease in vascular transit times (20%+/-8%), a dilatation of the capillary bed (10.9%+/-1.2%), and significant increases in red blood cell speed (33.0%+/-7.7%) and flux (19.5%+/-6.2%). Capillaries dilated more than the medium-caliber vessels, indicating a decreased heterogeneity in vessel volumes and increased blood flow-carrying capacity during neuronal activation relative to baseline. Capillary dilatation accounted for an estimated approximately 18% of the total change in the focal cerebral blood volume. In support of a capacity for focal redistribution of microvascular flow and volume, significant, though less frequent, local stimulation-induced decreases in capillary volume and erythrocyte speed and flux also occurred. The present findings provide further evidence of a strong functional reactivity of cerebral capillaries and underscore the importance of changes in the capillary geometry in the hemodynamic response to neuronal activation.

Complexity of treatment decisions with older patients: who, when and what to treat?

<h3>ABSTRACT</h3> <h3>Background</h3> Dystonia is an under-studied motor feature of Parkinson disease (PD). Although considerable efforts have focused on brain oscillations related to the cardinal symptoms of PD, whether dystonia is associated with specific electrophysiological features is unclear. <h3>Objectives</h3> To investigate subcortical and cortical field potentials at rest and during contralateral hand and foot movements in PD patients with and without dystonia. <h3>Methods</h3> We examined the prevalence and distribution of dystonia in PD patients undergoing deep brain stimulation surgery and recorded intracranial electrophysiology from motor cortex and directional electrodes in subthalamic nucleus (STN) both at rest and during self-paced repetitive contralateral hand and foot movements. Wavelet transforms and mixed models characterized changes in spectral content in patients with and without dystonia. <h3>Results</h3> Dystonia was highly prevalent at enrollment (61%) and occurred most commonly in the foot. Regardless of dystonia status, cortical recordings display beta (13-30 Hz) desynchronization during movements versus rest, while STN signals show increased power in low frequencies (6.0±3.3 and 4.2±2.9 Hz peak frequencies for hand and foot movements respectively). PD patients with dystonia during DBS surgery displayed greater M1 beta power at rest and STN low frequency power during movements versus those without dystonia. <h3>Conclusions</h3> Spectral power in motor cortex and STN field potentials differs markedly during repetitive limb movements, with cortical beta desynchronization and subcortical low frequency synchronization, especially in PD patients with dystonia. Greater knowledge on field potential dynamics in human motor circuits can inform dystonia pathophysiology in PD and guide novel approaches to therapy.