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Song H, Mah B, Sun Y, Aloysius N, Bai Y, Zhang L. Development of spontaneous recurrent seizures accompanied with increased rates of interictal spikes and decreased hippocampal delta and theta activities following extended kindling in mice. Exp Neurol 2024; 379:114860. [PMID: 38876195 DOI: 10.1016/j.expneurol.2024.114860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 05/30/2024] [Accepted: 06/09/2024] [Indexed: 06/16/2024]
Abstract
Interictal epileptiform discharges refer to aberrant brain electrographic signals between seizures and feature intermittent interictal spikes (ISs), sharp waves, and/or abnormal rhythms. Recognition of these epileptiform activities by electroencephalographic (EEG) examinations greatly aids epilepsy diagnosis and localization of the seizure onset zone. ISs are a major form of interictal epileptiform discharges recognized in animal models of epilepsy. Progressive changes in IS waveforms, IS rates, and/or associated fast ripple oscillations have been shown to precede the development of spontaneous recurrent seizures (SRS) in various animal models. IS expressions in the kindling model of epilepsy have been demonstrated but IS changes during the course of SRS development in extended kindled animals remain to be detailed. We hence addressed this issue using a mouse model of kindling-induced SRS. Adult C57 black mice received twice daily hippocampal stimulations until SRS occurrence, with 24-h EEG monitoring performed following 50, 80, and ≥ 100 stimulations and after observation of SRS. In the stimulated hippocampus, increases in spontaneous ISs rates, but not in IS waveforms nor IS-associated fast ripples, along with decreased frequencies of hippocampal delta and theta rhythms, were observed before SRS onset. Comparable increases in IS rates were further observed in the unstimulated hippocampus, piriform cortex, and entorhinal cortex, but not in the unstimulated parietal cortex and dorsomedial thalamus. These data provide original evidence suggesting that increases in hippocampal IS rates, together with reductions in hippocampal delta and theta rhythms are closely associated with development of SRS in a rodent kindling model.
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Affiliation(s)
- Hongmei Song
- Department of Neurosurgery, the First Hospital of Jilin University, China; Krembil Research Institute, University Health Network, Canada.
| | - Bryan Mah
- Krembil Research Institute, University Health Network, Canada
| | - Yuqing Sun
- Krembil Research Institute, University Health Network, Canada
| | - Nancy Aloysius
- Krembil Research Institute, University Health Network, Canada
| | - Yang Bai
- Department of Neuro-Oncology, the First Hospital of Jilin University, China.
| | - Liang Zhang
- Krembil Research Institute, University Health Network, Canada; Division of Neurology, Department of Medicine, University of Toronto, Toronto, Ontario, Canada.
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Wodeyar A, Chinappen D, Mylonas D, Baxter B, Manoach DS, Eden UT, Kramer MA, Chu CJ. Thalamic epileptic spikes disrupt sleep spindles in patients with epileptic encephalopathy. Brain 2024; 147:2803-2816. [PMID: 38650060 DOI: 10.1093/brain/awae119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 03/01/2024] [Accepted: 03/24/2024] [Indexed: 04/25/2024] Open
Abstract
In severe epileptic encephalopathies, epileptic activity contributes to progressive cognitive dysfunction. Epileptic encephalopathies share the trait of spike-wave activation during non-REM sleep (EE-SWAS), a sleep stage dominated by sleep spindles, which are brain oscillations known to coordinate offline memory consolidation. Epileptic activity has been proposed to hijack the circuits driving these thalamocortical oscillations, thereby contributing to cognitive impairment. Using a unique dataset of simultaneous human thalamic and cortical recordings in subjects with and without EE-SWAS, we provide evidence for epileptic spike interference of thalamic sleep spindle production in patients with EE-SWAS. First, we show that epileptic spikes and sleep spindles are both predicted by slow oscillations during stage two sleep (N2), but at different phases of the slow oscillation. Next, we demonstrate that sleep-activated cortical epileptic spikes propagate to the thalamus (thalamic spike rate increases after a cortical spike, P ≈ 0). We then show that epileptic spikes in the thalamus increase the thalamic spindle refractory period (P ≈ 0). Finally, we show that in three patients with EE-SWAS, there is a downregulation of sleep spindles for 30 s after each thalamic spike (P < 0.01). These direct human thalamocortical observations support a proposed mechanism for epileptiform activity to impact cognitive function, wherein epileptic spikes inhibit thalamic sleep spindles in epileptic encephalopathy with spike and wave activation during sleep.
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Affiliation(s)
- Anirudh Wodeyar
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
| | - Dhinakaran Chinappen
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Graduate Program in Neuroscience, Boston University, Boston, MA 02215, USA
| | - Dimitris Mylonas
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA 02215, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Bryan Baxter
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA 02215, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Dara S Manoach
- Department of Psychiatry, Massachusetts General Hospital, Boston, MA 02215, USA
- Division of Sleep Medicine, Harvard Medical School, Boston, MA 02115, USA
| | - Uri T Eden
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
| | - Mark A Kramer
- Department of Mathematics and Statistics, Boston University, Boston, MA 02215, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02215, USA
| | - Catherine J Chu
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA
- Harvard Medical School, Boston, MA 02115, USA
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Murray NWG, Kneebone AC, Graham PL, Wong CH, Savage G, Gillinder L, Fong MWK. The network is more important than the node: stereo-EEG evidence of neurocognitive networks in epilepsy. FRONTIERS IN NETWORK PHYSIOLOGY 2024; 4:1424004. [PMID: 39114571 PMCID: PMC11303167 DOI: 10.3389/fnetp.2024.1424004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Accepted: 07/01/2024] [Indexed: 08/10/2024]
Abstract
Introduction Neuropsychological assessment forms an integral part of the presurgical evaluation for patients with medically refractory focal epilepsy. Our understanding of cognitive impairment in epilepsy is based on seminal lesional studies that have demonstrated important structure-function relationships within the brain. However, a growing body of literature demonstrating heterogeneity in the cognitive profiles of patients with focal epilepsy (e.g., temporal lobe epilepsy; TLE) has led researchers to speculate that cognition may be impacted by regions outside the seizure onset zone, such as those involved in the interictal or "irritative" network. Methods Neuropsychological data from 48 patients who underwent stereoelectroencephalography (SEEG) monitoring between 2012 and 2023 were reviewed. Patients were categorized based on the site of seizure onset, as well as their irritative network, to determine the impact of wider network activity on cognition. Neuropsychological data were compared with normative standards (i.e., z = 0), and between groups. Results There were very few distinguishing cognitive features between patients when categorized based purely on the seizure onset zone (i.e., frontal lobe vs. temporal lobe epilepsy). In contrast, patients with localized irritative networks (i.e., frontal or temporal interictal epileptiform discharges [IEDs]) demonstrated more circumscribed profiles of impairment compared with those demonstrating wider irritative networks (i.e., frontotemporal IEDs). Furthermore, the directionality of propagation within the irritative network was found to influence the manifestations of cognitive impairment. Discussion The findings suggest that neuropsychological assessment is sensitive to network activity beyond the site of seizure onset. As such, an overly focal interpretation may not accurately reflect the distribution of the underlying pathology. This has important implications for presurgical work-up in epilepsy, as well as subsequent surgical outcomes.
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Affiliation(s)
- Nicholas W. G. Murray
- School of Psychological Sciences, Macquarie University, Sydney, Australia
- Westmead Comprehensive Epilepsy Centre, The University of Sydney, Sydney, Australia
| | - Anthony C. Kneebone
- School of Psychology, University of Queensland, Brisbane, Australia
- Department of Neurology and Stroke, Flinders Medical Centre, Adelaide, Australia
| | - Petra L. Graham
- School of Mathematical and Physical Sciences, Macquarie University, Sydney, Australia
| | - Chong H. Wong
- Westmead Comprehensive Epilepsy Centre, The University of Sydney, Sydney, Australia
| | - Greg Savage
- School of Psychological Sciences, Macquarie University, Sydney, Australia
| | - Lisa Gillinder
- Advanced Epilepsy Unit, The Mater Hospital, Brisbane, Australia
| | - Michael W. K. Fong
- Westmead Comprehensive Epilepsy Centre, The University of Sydney, Sydney, Australia
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT, United States
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Melzer N, Weber K, Räuber S, Rosenow F. [(Auto)immunity in focal epilepsy: mechanisms of (auto‑)immune-inflammatory epileptogenic neurodegeneration]. DER NERVENARZT 2024:10.1007/s00115-024-01695-5. [PMID: 38953922 DOI: 10.1007/s00115-024-01695-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 06/07/2024] [Indexed: 07/04/2024]
Abstract
OBJECTIVE While the neuronal mechanisms of epileptic hyperexcitability (HE) have been studied in detail, recent findings suggest that extraneuronal, mainly immune-mediated inflammatory and vascular mechanisms play an important role in the development and progression of HE in epilepsy and the cognitive and behavioral comorbidities. MATERIAL AND METHODS Narrative review. RESULTS As in autoimmune (limbic) encephalitis (ALE/AIE) or Rasmussen's encephalitis (RE), the primary adaptive and innate immune responses and associated changes in the blood-brain barrier (BBB) and neurovascular unit (NVU) can cause acute cortical hyperexcitability (HE) and the development of hippocampal sclerosis (HS) and other structural cortical lesions with chronic HE. Cortical HE, which is associated with malformation of cortical development (MCD) and low-grade epilepsy-associated tumors (LEAT), for example, can be accompanied by secondary adaptive and innate immune responses and alterations in the BBB and NVU, potentially modulating the ictogenicity and epileptogenicity. These associations illustrate the influence of adaptive and innate immune mechanisms and associated changes in the BBB and NVU on cortical excitability and vice versa, suggesting a dynamic and complex interplay of these factors in the development and progression of epilepsy in general. DISCUSSION The described concept of a neuro-immune-vascular interaction in focal epilepsy opens up new possibilities for the pathogenetic understanding and thus also for the selective therapeutic intervention.
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Affiliation(s)
- Nico Melzer
- Klinik für Neurologie, Medizinische Fakultät und Universitätsklinikum, Heinrich-Heine-Universität Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Deutschland.
| | - Katharina Weber
- Neurologisches Institut (Edinger Institut), Universitätsklinikum Frankfurt, Goethe-Universität Frankfurt, Frankfurt am Main, Deutschland
- Frankfurt Cancer Institute (FCI), Goethe-Universität Frankfurt, Frankfurt am Main, Deutschland
- Partnerstätte Frankfurt, Frankfurt am Main und Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Deutsches Konsortium für Translationale Krebsforschung (DKTK), Heidelberg, Deutschland
- Universitäres Centrum für Tumorerkrankungen Frankfurt (UCT), Universitätsklinikum Frankfurt, Goethe-Universität Frankfurt, Frankfurt am Main, Deutschland
| | - Saskia Räuber
- Klinik für Neurologie, Medizinische Fakultät und Universitätsklinikum, Heinrich-Heine-Universität Düsseldorf, Moorenstraße 5, 40225, Düsseldorf, Deutschland
| | - Felix Rosenow
- Epilepsiezentrum Frankfurt Rhein-Main, Klinik für Neurologie, Zentrum für Neurologie und Neurochirurgie, Universitätsklinikum Frankfurt, Goethe-Universität Frankfurt, Frankfurt am Main, Deutschland.
- LOEWE Center for Personalized Translational Epilepsy Research (CePTER), Goethe-Universität Frankfurt, Frankfurt am Main, Deutschland.
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Schreiner T, Griffiths BJ, Kutlu M, Vollmar C, Kaufmann E, Quach S, Remi J, Noachtar S, Staudigl T. Spindle-locked ripples mediate memory reactivation during human NREM sleep. Nat Commun 2024; 15:5249. [PMID: 38898100 PMCID: PMC11187142 DOI: 10.1038/s41467-024-49572-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 06/11/2024] [Indexed: 06/21/2024] Open
Abstract
Memory consolidation relies in part on the reactivation of previous experiences during sleep. The precise interplay of sleep-related oscillations (slow oscillations, spindles and ripples) is thought to coordinate the information flow between relevant brain areas, with ripples mediating memory reactivation. However, in humans empirical evidence for a role of ripples in memory reactivation is lacking. Here, we investigated the relevance of sleep oscillations and specifically ripples for memory reactivation during human sleep using targeted memory reactivation. Intracranial electrophysiology in epilepsy patients and scalp EEG in healthy participants revealed that elevated levels of slow oscillation - spindle activity coincided with the read-out of experimentally induced memory reactivation. Importantly, spindle-locked ripples recorded intracranially from the medial temporal lobe were found to be correlated with the identification of memory reactivation during non-rapid eye movement sleep. Our findings establish ripples as key-oscillation for sleep-related memory reactivation in humans and emphasize the importance of the coordinated interplay of the cardinal sleep oscillations.
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Affiliation(s)
- Thomas Schreiner
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Benjamin J Griffiths
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
- Centre for Human Brain Health, University of Birmingham, Birmingham, UK
| | - Merve Kutlu
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Vollmar
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Elisabeth Kaufmann
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefanie Quach
- Department of Neurosurgery, University Hospital Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jan Remi
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Soheyl Noachtar
- Epilepsy Center, Department of Neurology, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tobias Staudigl
- Department of Psychology, Ludwig-Maximilians-Universität München, Munich, Germany.
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Ye H, Chen C, Weiss SA, Wang S. Pathological and Physiological High-frequency Oscillations on Electroencephalography in Patients with Epilepsy. Neurosci Bull 2024; 40:609-620. [PMID: 37999861 PMCID: PMC11127900 DOI: 10.1007/s12264-023-01150-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2023] [Accepted: 09/28/2023] [Indexed: 11/25/2023] Open
Abstract
High-frequency oscillations (HFOs) encompass ripples (80 Hz-200 Hz) and fast ripples (200 Hz-600 Hz), serving as a promising biomarker for localizing the epileptogenic zone in epilepsy. Spontaneous fast ripples are always pathological, while ripples may be physiological or pathological. Distinguishing physiological from pathological ripples is important not only for designating epileptogenic brain regions, but also for investigations that study ripples in the context of memory encoding, consolidation, and recall in patients with epilepsy. Many studies have sought to identify distinguishing features between pathological and physiological ripples over the past two decades. Physiological and pathological ripples differ with respect to their spatial location, cellular mechanisms, morphology, and coupling with background electroencephalographic activity. Retrospective studies have demonstrated that differentiating between pathological and physiological ripples can improve surgical outcome prediction. In this review, we summarize the characteristics, differences, and applications of pathological and physiological HFOs and discuss strategies for their clinical translation.
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Affiliation(s)
- Hongyi Ye
- Department of Neurology, Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Cong Chen
- Department of Neurology, Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China
| | - Shennan A Weiss
- Department of Neurology, State University of New York Downstate, Brooklyn, NY, 11203, USA
- Department of Physiology and Pharmacology, State University of New York Downstate, Brooklyn, NY, 11203, USA
- Department of Neurology, New York City Health + Hospitals/Kings County, Brooklyn, NY, 11203, USA
| | - Shuang Wang
- Department of Neurology, Epilepsy Center, Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, 310009, China.
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Fu Y, Zhang J, Cao Y, Ye L, Zheng R, Li Q, Shen B, Shi Y, Cao J, Fang J. Recognition memory deficits detected through eye-tracking in well-controlled children with self-limited epilepsy with centrotemporal spikes. Epilepsia 2024; 65:1128-1140. [PMID: 38299621 DOI: 10.1111/epi.17902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 02/02/2024]
Abstract
OBJECTIVE Children with self-limited epilepsy characterized by centrotemporal spikes (SeLECTS) exhibit cognitive deficits in memory during the active phase, but there is currently a lack of studies and techniques to assess their memory development after well-controlled seizures. In this study, we employed eye-tracking techniques to investigate visual memory and its association with clinical factors and global intellectual ability, aiming to identify potential risk factors by examining encoding and recognition processes. METHODS A total of 26 recruited patients diagnosed with SeLECTS who had been seizure-free for at least 2 years, along with 24 control subjects, underwent Wechsler cognitive assessment and an eye-movement-based memory task while video-electroencephalographic (EEG) data were recorded. Fixation and pupil data related to eye movements were utilized to detect distinct memory processes and subsequently to compare the cognitive performance of patients exhibiting different regression patterns on EEG. RESULTS The findings revealed persistent impairments in visual memory among children with SeLECTS after being well controlled, primarily observed in the recognition stage rather than the encoding phase. Furthermore, the age at onset, frequency of seizures, and interictal epileptiform discharges exhibited significant correlations with eye movement data. SIGNIFICANCE Children with SeLECTS exhibit persistent recognition memory impairment after being well controlled for the disease. Controlling the frequency of seizures and reducing prolonged epileptiform activity may improve memory cognitive development. The application of the eye-tracking technique may provide novel insights into exploring memory cognition as well as underlying mechanisms associated with pediatric epilepsy.
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Affiliation(s)
- Yanlu Fu
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Jingxin Zhang
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Yina Cao
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Linmei Ye
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Runze Zheng
- Artificial Intelligence Institute, Hangzhou Dianzi University School of Automation, Hangzhou, Zhejiang, China
| | - Qiwei Li
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Beibei Shen
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Yi Shi
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
| | - Jiuwen Cao
- Artificial Intelligence Institute, Hangzhou Dianzi University School of Automation, Hangzhou, Zhejiang, China
| | - Jiajia Fang
- Department of Neurology, Fourth Affiliated Hospital Zhejiang University School of Medicine, Yiwu, Zhejiang, China
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Liu AA, Barr WB. Overlapping and distinct phenotypic profiles in Alzheimer's disease and late onset epilepsy: a biologically-based approach. Front Neurol 2024; 14:1260523. [PMID: 38545454 PMCID: PMC10965692 DOI: 10.3389/fneur.2023.1260523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/18/2023] [Indexed: 04/05/2024] Open
Abstract
Due to shared hippocampal dysfunction, patients with Alzheimer's dementia and late-onset epilepsy (LOE) report memory decline. Multiple studies have described the epidemiological, pathological, neurophysiological, and behavioral overlap between Alzheimer's Disease and LOE, implying a bi-directional relationship. We describe the neurobiological decline occurring at different spatial in AD and LOE patients, which may explain why their phenotypes overlap and differ. We provide suggestions for clinical recognition of dual presentation and novel approaches for behavioral testing that reflect an "inside-out," or biologically-based approach to testing memory. New memory and language assessments could detect-and treat-memory impairment in AD and LOE at an earlier, actionable stage.
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Affiliation(s)
- Anli A. Liu
- Langone Medical Center, New York University, New York, NY, United States
- Department of Neurology, School of Medicine, New York University, New York, NY, United States
- Neuroscience Institute, Langone Medical Center, New York University, New York, NY, United States
| | - William B. Barr
- Department of Neurology, School of Medicine, New York University, New York, NY, United States
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Kunz L, Staresina BP, Reinacher PC, Brandt A, Guth TA, Schulze-Bonhage A, Jacobs J. Ripple-locked coactivity of stimulus-specific neurons and human associative memory. Nat Neurosci 2024; 27:587-599. [PMID: 38366143 PMCID: PMC10917673 DOI: 10.1038/s41593-023-01550-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 12/11/2023] [Indexed: 02/18/2024]
Abstract
Associative memory enables the encoding and retrieval of relations between different stimuli. To better understand its neural basis, we investigated whether associative memory involves temporally correlated spiking of medial temporal lobe (MTL) neurons that exhibit stimulus-specific tuning. Using single-neuron recordings from patients with epilepsy performing an associative object-location memory task, we identified the object-specific and place-specific neurons that represented the separate elements of each memory. When patients encoded and retrieved particular memories, the relevant object-specific and place-specific neurons activated together during hippocampal ripples. This ripple-locked coactivity of stimulus-specific neurons emerged over time as the patients' associative learning progressed. Between encoding and retrieval, the ripple-locked timing of coactivity shifted, suggesting flexibility in the interaction between MTL neurons and hippocampal ripples according to behavioral demands. Our results are consistent with a cellular account of associative memory, in which hippocampal ripples coordinate the activity of specialized cellular populations to facilitate links between stimuli.
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Affiliation(s)
- Lukas Kunz
- Department of Epileptology, University Hospital Bonn, Bonn, Germany.
- Epilepsy Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany.
| | - Bernhard P Staresina
- Department of Experimental Psychology, University of Oxford, Oxford, UK
- Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK
| | - Peter C Reinacher
- Department of Stereotactic and Functional Neurosurgery, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
- Fraunhofer Institute for Laser Technology, Aachen, Germany
| | - Armin Brandt
- Epilepsy Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Tim A Guth
- Department of Epileptology, University Hospital Bonn, Bonn, Germany
- Epilepsy Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Andreas Schulze-Bonhage
- Epilepsy Center, Medical Center - University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Joshua Jacobs
- Department of Biomedical Engineering, Columbia University, New York, NY, USA
- Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA
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Sakon JJ, Halpern DJ, Schonhaut DR, Kahana MJ. Human Hippocampal Ripples Signal Encoding of Episodic Memories. J Neurosci 2024; 44:e0111232023. [PMID: 38233218 PMCID: PMC10883616 DOI: 10.1523/jneurosci.0111-23.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Revised: 11/28/2023] [Accepted: 12/01/2023] [Indexed: 01/19/2024] Open
Abstract
Direct human brain recordings have confirmed the presence of high-frequency oscillatory events, termed ripples, during awake behavior. While many prior studies have focused on medial temporal lobe (MTL) ripples during memory retrieval, here we investigate ripples during memory encoding. Specifically, we ask whether ripples during encoding predict whether and how memories are subsequently recalled. Detecting ripples from MTL electrodes implanted in 116 neurosurgical participants (n = 61 male) performing a verbal episodic memory task, we find that encoding ripples do not distinguish recalled from not recalled items in any MTL region, even as high-frequency activity during encoding predicts recall in these same regions. Instead, hippocampal ripples increase during encoding of items that subsequently lead to recall of temporally and semantically associated items during retrieval, a phenomenon known as clustering. This subsequent clustering effect arises specifically when hippocampal ripples co-occur during encoding and retrieval, suggesting that ripples mediate both encoding and reinstatement of episodic memories.
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Affiliation(s)
- John J Sakon
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104
| | - David J Halpern
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104
| | - Daniel R Schonhaut
- Department of Neuroscience, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104
| | - Michael J Kahana
- Department of Psychology, University of Pennsylvania, Philadelphia, PA 19104
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11
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McLaren JR, Kahle KT, Richardson RM, Chu CJ. Epilepsy Surgery for Cognitive Improvement in Epileptic Encephalopathy. Neurosurg Clin N Am 2024; 35:49-59. [PMID: 38000841 DOI: 10.1016/j.nec.2023.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2023]
Abstract
Epileptic encephalopathies are defined by the presence of frequent epileptiform activity that causes neurodevelopmental slowing or regression. Here, we review evidence that epilepsy surgery improves neurodevelopment in children with epileptic encephalopathies. We describe an example patient with epileptic encephalopathy without drug refractory seizures, who underwent successful diagnostic and therapeutic surgeries. In patients with epileptic encephalopathy, cognitive improvement alone is a sufficient indication to recommend surgical intervention in experienced centers.
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Affiliation(s)
- John R McLaren
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School
| | - Kristopher T Kahle
- Harvard Medical School; Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit Street, Wang Building Room 333, Boston, MA 02114, USA
| | - R Mark Richardson
- Harvard Medical School; Department of Neurosurgery, Massachusetts General Hospital, 55 Fruit Street, Their Building, 4th Floor, Boston, MA 02114, USA
| | - Catherine J Chu
- Department of Neurology, Massachusetts General Hospital, Boston, MA 02114, USA; Harvard Medical School.
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12
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Silva AB, Leonard MK, Oganian Y, D’Esopo E, Krish D, Kopald B, Tran EB, Chang EF, Kleen JK. Interictal epileptiform discharges contribute to word-finding difficulty in epilepsy through multiple cognitive mechanisms. Epilepsia 2023; 64:3266-3278. [PMID: 37753856 PMCID: PMC10841419 DOI: 10.1111/epi.17781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 09/22/2023] [Accepted: 09/25/2023] [Indexed: 09/28/2023]
Abstract
OBJECTIVE Cognitive impairment often impacts quality of life in epilepsy even if seizures are controlled. Word-finding difficulty is particularly prevalent and often attributed to etiological (static, baseline) circuit alterations. We sought to determine whether interictal discharges convey significant superimposed contributions to word-finding difficulty in patients, and if so, through which cognitive mechanism(s). METHODS Twenty-three patients undergoing intracranial monitoring for drug-resistant epilepsy participated in multiple tasks involving word production (auditory naming, short-term verbal free recall, repetition) to probe word-finding difficulty across different cognitive domains. We compared behavioral performance between trials with versus without interictal discharges across six major brain areas and adjusted for intersubject differences using mixed-effects models. We also evaluated for subjective word-finding difficulties through retrospective chart review. RESULTS Subjective word-finding difficulty was reported by the majority (79%) of studied patients preoperatively. During intracranial recordings, interictal epileptiform discharges (IEDs) in the medial temporal lobe were associated with long-term lexicosemantic memory impairments as indexed by auditory naming (p = .009), in addition to their established impact on short-term verbal memory as indexed by free recall (p = .004). Interictal discharges involving the lateral temporal cortex and lateral frontal cortex were associated with delayed reaction time in the auditory naming task (p = .016 and p = .018), as well as phonological working memory impairments as indexed by repetition reaction time (p = .002). Effects of IEDs across anatomical regions were strongly dependent on their precise timing within the task. SIGNIFICANCE IEDs appear to act through multiple cognitive mechanisms to form a convergent basis for the debilitating clinical word-finding difficulty reported by patients with epilepsy. This was particularly notable for medial temporal spikes, which are quite common in adult focal epilepsy. In parallel with the treatment of seizures, the modulation of interictal discharges through emerging pharmacological means and neurostimulation approaches may be an opportunity to help address devastating memory and language impairments in epilepsy.
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Affiliation(s)
- Alexander B. Silva
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
- Medical Scientist Training Program, University of California, San Francisco, CA, USA
- University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Matthew K. Leonard
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | | | - Emma D’Esopo
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Devon Krish
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Brandon Kopald
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Edwina B. Tran
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
| | - Edward F. Chang
- Department of Neurosurgery, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
- University of California, Berkeley - University of California, San Francisco Graduate Program in Bioengineering, Berkeley, CA, USA
| | - Jonathan K. Kleen
- Department of Neurology, Weill Institute of Neurosciences, University of California San Francisco, San Francisco, CA, USA
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Bernard C, Frauscher B, Gelinas J, Timofeev I. Sleep, oscillations, and epilepsy. Epilepsia 2023; 64 Suppl 3:S3-S12. [PMID: 37226640 PMCID: PMC10674035 DOI: 10.1111/epi.17664] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/27/2023] [Accepted: 05/23/2023] [Indexed: 05/26/2023]
Abstract
Sleep and wake are defined through physiological and behavioral criteria and can be typically separated into non-rapid eye movement (NREM) sleep stages N1, N2, and N3, rapid eye movement (REM) sleep, and wake. Sleep and wake states are not homogenous in time. Their properties vary during the night and day cycle. Given that brain activity changes as a function of NREM, REM, and wake during the night and day cycle, are seizures more likely to occur during NREM, REM, or wake at a specific time? More generally, what is the relationship between sleep-wake cycles and epilepsy? We will review specific examples from clinical data and results from experimental models, focusing on the diversity and heterogeneity of these relationships. We will use a top-down approach, starting with the general architecture of sleep, followed by oscillatory activities, and ending with ionic correlates selected for illustrative purposes, with respect to seizures and interictal spikes. The picture that emerges is that of complexity; sleep disruption and pathological epileptic activities emerge from reorganized circuits. That different circuit alterations can occur across patients and models may explain why sleep alterations and the timing of seizures during the sleep-wake cycle are patient-specific.
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Affiliation(s)
| | - Birgit Frauscher
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jennifer Gelinas
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Igor Timofeev
- Faculté de Médecine, Département de Psychiatrie et de Neurosciences, Centre de Recherche CERVO, Université Laval, Québec, QC G1J2G3, Canada
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14
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Ciliento R, Gjini K, Dabbs K, Hermann B, Riedner B, Jones S, Fatima S, Johnson S, Bendlin B, Lam AD, Boly M, Struck AF. Prevalence and localization of nocturnal epileptiform discharges in mild cognitive impairment. Brain Commun 2023; 5:fcad302. [PMID: 37965047 PMCID: PMC10642616 DOI: 10.1093/braincomms/fcad302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 09/18/2023] [Accepted: 11/06/2023] [Indexed: 11/16/2023] Open
Abstract
Recent evidence shows that identifying and treating epileptiform abnormalities in patients with Alzheimer's disease could represent a potential avenue to improve clinical outcome. Specifically, animal and human studies have revealed that in the early phase of Alzheimer's disease, there is an increased risk of seizures. It has also been demonstrated that the administration of anti-seizure medications can slow the functional progression of the disease only in patients with EEG signs of cortical hyperexcitability. In addition, although it is not known at what disease stage hyperexcitability emerges, there remains no consensus regarding the imaging and diagnostic methods best able to detect interictal events to further distinguish different phenotypes of Alzheimer's disease. In this exploratory work, we studied 13 subjects with amnestic mild cognitive impairment and 20 healthy controls using overnight high-density EEG with 256 channels. All participants also underwent MRI and neuropsychological assessment. Electronic source reconstruction was also used to better select and localize spikes. We found spikes in six of 13 (46%) amnestic mild cognitive impairment compared with two of 20 (10%) healthy control participants (P = 0.035), representing a spike prevalence similar to that detected in previous studies of patients with early-stage Alzheimer's disease. The interictal events were low-amplitude temporal spikes more prevalent during non-rapid eye movement sleep. No statistically significant differences were found in cognitive performance between amnestic mild cognitive impairment patients with and without spikes, but a trend in immediate and delayed memory was observed. Moreover, no imaging findings of cortical and subcortical atrophy were found between amnestic mild cognitive impairment participants with and without epileptiform spikes. In summary, our exploratory study shows that patients with amnestic mild cognitive impairment reveal EEG signs of hyperexcitability early in the disease course, while no other significant differences in neuropsychological or imaging features were observed among the subgroups. If confirmed with longitudinal data, these exploratory findings could represent one of the first signatures of a preclinical epileptiform phenotype of amnestic mild cognitive impairment and its progression.
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Affiliation(s)
- Rosario Ciliento
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Klevest Gjini
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Kevin Dabbs
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Bruce Hermann
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Brady Riedner
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA
| | - Stephanie Jones
- Department of Psychiatry, University of Wisconsin-Madison, Madison, WI 53719, USA
| | - Safoora Fatima
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Sterling Johnson
- Department of Medicine, University of Wisconsin, Madison, WI 53705, USA
| | - Barbara Bendlin
- Department of Medicine, University of Wisconsin, Madison, WI 53705, USA
| | - Alice D Lam
- Department of Neurology, Harvard Medical School, Massachusetts General Hospital, Boston, MA 02115, USA
| | - Melanie Boly
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
| | - Aaron F Struck
- Department of Neurology, University of Wisconsin-Madison, Madison, WI 53726, USA
- Department of Neurology, William S. Middleton Veterans Administration Hospital, Madison, WI 53705, USA
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15
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Kleen JK, Davis KA. Is It Reasonable to Drive When There Is a (Spike) Train? Neurology 2023; 101:377-379. [PMID: 37414566 DOI: 10.1212/wnl.0000000000207651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 05/31/2023] [Indexed: 07/08/2023] Open
Affiliation(s)
- Jonathan K Kleen
- From the Department of Neurology (J.K.K.), and Weill Institute for Neurosciences (J.K.K.), University of California, San Francisco; and Department of Neurology (K.A.D.), Perelman School of Medicine, and Center for Neuroengineering & Therapeutics (K.A.D.), University of Pennsylvania, Philadelphia
| | - Kathryn A Davis
- From the Department of Neurology (J.K.K.), and Weill Institute for Neurosciences (J.K.K.), University of California, San Francisco; and Department of Neurology (K.A.D.), Perelman School of Medicine, and Center for Neuroengineering & Therapeutics (K.A.D.), University of Pennsylvania, Philadelphia.
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16
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Soula M, Maslarova A, Harvey RE, Valero M, Brandner S, Hamer H, Fernández‐Ruiz A, Buzsáki G. Interictal epileptiform discharges affect memory in an Alzheimer's disease mouse model. Proc Natl Acad Sci U S A 2023; 120:e2302676120. [PMID: 37590406 PMCID: PMC10450667 DOI: 10.1073/pnas.2302676120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Accepted: 07/06/2023] [Indexed: 08/19/2023] Open
Abstract
Interictal epileptiform discharges (IEDs) are transient abnormal electrophysiological events commonly observed in epilepsy patients but are also present in other neurological diseases, such as Alzheimer's disease (AD). Understanding the role IEDs have on the hippocampal circuit is important for our understanding of the cognitive deficits seen in epilepsy and AD. We characterize and compare the IEDs of human epilepsy patients from microwire hippocampal recording with those of AD transgenic mice with implanted multilayer hippocampal silicon probes. Both the local field potential features and firing patterns of pyramidal cells and interneurons were similar in the mouse and human. We found that as IEDs emerged from the CA3-1 circuits, they recruited pyramidal cells and silenced interneurons, followed by post-IED suppression. IEDs suppressed the incidence and altered the properties of physiological sharp-wave ripples, altered their physiological properties, and interfered with the replay of place field sequences in a maze. In addition, IEDs in AD mice inversely correlated with daily memory performance. Together, our work implies that IEDs may present a common and epilepsy-independent phenomenon in neurodegenerative diseases that perturbs hippocampal-cortical communication and interferes with memory.
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Affiliation(s)
- Marisol Soula
- Neuroscience Institute, Langone Medical Center, New York University, New York, NY10016
| | - Anna Maslarova
- Neuroscience Institute, Langone Medical Center, New York University, New York, NY10016
- Department of Neurosurgery, Erlangen University Hospital, Friedrich Alexander University Erlangen-Nuremberg, 91054Erlangen, Germany
| | - Ryan E. Harvey
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY14853
| | - Manuel Valero
- Hospital del Mar Medical Research Institute, Barcelona Biomedical Research Park, Barcelona08003, Spain
| | - Sebastian Brandner
- Department of Neurosurgery, Erlangen University Hospital, Friedrich Alexander University Erlangen-Nuremberg, 91054Erlangen, Germany
| | - Hajo Hamer
- Department of Neurology, Epilepsy Center, Erlangen University Hospital, Friedrich Alexander University Erlangen-Nuremberg, 91054Erlangen, Germany
| | | | - György Buzsáki
- Neuroscience Institute, Langone Medical Center, New York University, New York, NY10016
- Department of Physiology and Neuroscience, Langone Medical Center, New York University, New York, NY10016
- Department of Neurology, Langone Medical Center, New York University, New York, NY10016
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17
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Dellavale D, Bonini F, Pizzo F, Makhalova J, Wendling F, Badier JM, Bartolomei F, Bénar CG. Spontaneous fast-ultradian dynamics of polymorphic interictal events in drug-resistant focal epilepsy. Epilepsia 2023; 64:2027-2043. [PMID: 37199673 DOI: 10.1111/epi.17655] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 05/16/2023] [Accepted: 05/16/2023] [Indexed: 05/19/2023]
Abstract
OBJECTIVE We studied the rate dynamics of interictal events occurring over fast-ultradian time scales, as commonly examined in clinics to guide surgical planning in epilepsy. METHODS Stereo-electroencephalography (SEEG) traces of 35 patients with good surgical outcome (Engel I) were analyzed. For this we developed a general data mining method aimed at clustering the plethora of transient waveform shapes including interictal epileptiform discharges (IEDs) and assessed the temporal fluctuations in the capability of mapping the epileptogenic zone (EZ) of each type of event. RESULTS We found that the fast-ultradian dynamics of the IED rate may effectively impair the precision of EZ identification, and appear to occur spontaneously, that is, not triggered by or exclusively associated with a particular cognitive task, wakefulness, sleep, seizure occurrence, post-ictal state, or antiepileptic drug withdrawal. Propagation of IEDs from the EZ to the propagation zone (PZ) could explain the observed fast-ultradian fluctuations in a reduced fraction of the analyzed patients, suggesting that other factors like the excitability of the epileptogenic tissue could play a more relevant role. A novel link was found between the fast-ultradian dynamics of the overall rate of polymorphic events and the rate of specific IEDs subtypes. We exploited this feature to estimate in each patient the 5 min interictal epoch for near-optimal EZ and resected-zone (RZ) localization. This approach produces at the population level a better EZ/RZ classification when compared to both (1) the whole time series available in each patient (p = .084 for EZ, p < .001 for RZ, Wilcoxon signed-rank test) and (2) 5 min epochs sampled randomly from the interictal recordings of each patient (p < .05 for EZ, p < .001 for RZ, 105 random samplings). SIGNIFICANCE Our results highlight the relevance of the fast-ultradian IED dynamics in mapping the EZ, and show how this dynamics can be estimated prospectively to inform surgical planning in epilepsy.
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Affiliation(s)
- Damián Dellavale
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
- Centro Atómico Bariloche and Instituto Balseiro, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad Nacional de Cuyo (UNCUYO), Río Negro, San Carlos de Bariloche, Argentina
| | - Francesca Bonini
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
- Epileptology and Cerebral Rhythmology, APHM, Timone Hospital, Marseille, France
| | - Francesca Pizzo
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
- Epileptology and Cerebral Rhythmology, APHM, Timone Hospital, Marseille, France
| | - Julia Makhalova
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
- Epileptology and Cerebral Rhythmology, APHM, Timone Hospital, Marseille, France
| | | | - Jean-Michel Badier
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
| | - Fabrice Bartolomei
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
- Epileptology and Cerebral Rhythmology, APHM, Timone Hospital, Marseille, France
| | - Christian-George Bénar
- Institut de Neurosciences des Systèmes (INS, UMR1106), Aix Marseille Université, INSERM, Marseille, France
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18
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Duan QT, Dai L, Wang LK, Shi XJ, Chen X, Liao X, Zhang CQ, Yang H. Hippocampal ripples correlate with memory performance in humans. Brain Res 2023; 1810:148370. [PMID: 37080267 DOI: 10.1016/j.brainres.2023.148370] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2023] [Revised: 04/06/2023] [Accepted: 04/13/2023] [Indexed: 04/22/2023]
Abstract
Memory performance evaluation has generally been based on behavioral tests in the past decades. However, its neural correlates remain largely unknown, particularly in humans. Here we addressed this question using intracranial electroencephalography in patients with refractory epilepsy, performing an episodic memory test. We used the presurgical Wechsler Memory Scale (WMS) test to assess the memory performance of each patient. We found that hippocampal ripples significantly exhibited a transient increase during visual stimulation or before verbal recall. This increase in hippocampal ripples positively correlated with memory performance. By contrast, memory performance is negatively correlated with hippocampal interictal epileptic discharges (IEDs) or epileptic ripples in the memory task. However, these correlations were not present during quiet wakefulness. Thus, our findings uncover the neural correlates of memory performance in addition to traditional behavioral tests.
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Affiliation(s)
- Qing-Tian Duan
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Lu Dai
- Center for Neurointelligence, School of Medicine, Chongqing University, Chongqing 400030, China
| | - Lu-Kang Wang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xian-Jun Shi
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xiaowei Chen
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing 400038, China; Chongqing Institute for Brain and Intelligence, Guangyang Bay Laboratory, Chongqing 400064, China
| | - Xiang Liao
- Center for Neurointelligence, School of Medicine, Chongqing University, Chongqing 400030, China.
| | - Chun-Qing Zhang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China; Chongqing Institute for Brain and Intelligence, Guangyang Bay Laboratory, Chongqing 400064, China.
| | - Hui Yang
- Department of Neurosurgery, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China; Chongqing Institute for Brain and Intelligence, Guangyang Bay Laboratory, Chongqing 400064, China.
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19
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Soula M, Maslarova A, Harvey RE, Valero M, Brandner S, Hamer H, Fernández-Ruiz A, Buzsáki G. Interictal epileptiform discharges affect memory in an Alzheimer's Disease mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528683. [PMID: 36824810 PMCID: PMC9949089 DOI: 10.1101/2023.02.15.528683] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Interictal epileptiform discharges (IEDs) are transient abnormal electrophysiological events commonly observed in epilepsy patients but are also present in other neurological disease, such as Alzheimer's Disease (AD). Understanding the role IEDs have on the hippocampal circuit is important for our understanding of the cognitive deficits seen in epilepsy and AD. We characterize and compare the IEDs of human epilepsy patients from microwire hippocampal recording with those of AD transgenic mice with implanted multi-layer hippocampal silicon probes. Both the local field potential features and firing patterns of pyramidal cells and interneurons were similar in mouse and human. We found that as IEDs emerged from the CA3-1 circuits, they recruited pyramidal cells and silenced interneurons, followed by post-IED suppression. IEDs suppressed the incidence and altered the properties of physiological sharp-wave ripples (SPW-Rs), altered their physiological properties, and interfered with the replay of place field sequences in a maze. In addition, IEDs in AD mice inversely correlated with daily memory performance. Together, our work implicates that IEDs may present a common and epilepsy-independent phenomenon in neurodegenerative diseases that perturbs hippocampal-cortical communication and interferes with memory. Significant Statement Prevalence of neurodegenerative diseases and the number of people with dementia is increasing steadily. Therefore, novel treatment strategies for learning and memory disorders are urgently necessary. IEDs, apart from being a surrogate for epileptic brain regions, have also been linked to cognitive decline. Here we report that IEDs in human epilepsy patients and AD mouse models have similar local field potential characteristics and associated firing patterns of pyramidal cells and interneurons. Mice with more IEDs displayed fewer hippocampal SPW-Rs, poorer replay of spatial trajectories, and decreased memory performance. IED suppression is an unexplored target to treat cognitive dysfunction in neurodegenerative diseases.
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20
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Lippmann K, Klaft ZJ, Salar S, Hollnagel JO, Valero M, Maslarova A. Status epilepticus induces chronic silencing of burster and dominance of regular firing neurons during sharp wave-ripples in the mouse subiculum. Neurobiol Dis 2022; 175:105929. [DOI: 10.1016/j.nbd.2022.105929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/08/2022] [Accepted: 11/17/2022] [Indexed: 11/23/2022] Open
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21
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Liu AA, Henin S, Abbaspoor S, Bragin A, Buffalo EA, Farrell JS, Foster DJ, Frank LM, Gedankien T, Gotman J, Guidera JA, Hoffman KL, Jacobs J, Kahana MJ, Li L, Liao Z, Lin JJ, Losonczy A, Malach R, van der Meer MA, McClain K, McNaughton BL, Norman Y, Navas-Olive A, de la Prida LM, Rueckemann JW, Sakon JJ, Skelin I, Soltesz I, Staresina BP, Weiss SA, Wilson MA, Zaghloul KA, Zugaro M, Buzsáki G. A consensus statement on detection of hippocampal sharp wave ripples and differentiation from other fast oscillations. Nat Commun 2022; 13:6000. [PMID: 36224194 PMCID: PMC9556539 DOI: 10.1038/s41467-022-33536-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 09/21/2022] [Indexed: 02/05/2023] Open
Abstract
Decades of rodent research have established the role of hippocampal sharp wave ripples (SPW-Rs) in consolidating and guiding experience. More recently, intracranial recordings in humans have suggested their role in episodic and semantic memory. Yet, common standards for recording, detection, and reporting do not exist. Here, we outline the methodological challenges involved in detecting ripple events and offer practical recommendations to improve separation from other high-frequency oscillations. We argue that shared experimental, detection, and reporting standards will provide a solid foundation for future translational discovery.
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Affiliation(s)
- Anli A Liu
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, USA
- Neuroscience Institute, NYU Langone Medical Center, New York, NY, USA
| | - Simon Henin
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, USA
| | - Saman Abbaspoor
- Department of Psychology, Vanderbilt University, Nashville, TN, USA
| | - Anatol Bragin
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Elizabeth A Buffalo
- Department of Physiology and Biophysics, Washington National Primate Center, University of Washington, Seattle, WA, USA
| | - Jordan S Farrell
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - David J Foster
- Department of Psychology and Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Loren M Frank
- Kavli Institute for Fundamental Neuroscience, Center for Integrative Neuroscience and Department of Physiology, University of California San Francisco, San Francisco, CA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Tamara Gedankien
- Department of Biomedical Engineering, Department of Neurological Surgery, Columbia University, New York, NY, USA
| | - Jean Gotman
- Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Jennifer A Guidera
- Kavli Institute for Fundamental Neuroscience, Center for Integrative Neuroscience and Department of Physiology, University of California San Francisco, San Francisco, CA, USA
- Medical Scientist Training Program, Department of Bioengineering, University of California, San Francisco, San Francisco, CA, USA
| | - Kari L Hoffman
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN, USA
| | - Joshua Jacobs
- Department of Biomedical Engineering, Department of Neurological Surgery, Columbia University, New York, NY, USA
| | - Michael J Kahana
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Lin Li
- Department of Biomedical Engineering, University of North Texas, Denton, TX, USA
| | - Zhenrui Liao
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Jack J Lin
- Department of Neurology, Center for Mind and Brain, University of California Davis, Oakland, CA, USA
| | - Attila Losonczy
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Rafael Malach
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | | | - Kathryn McClain
- Neuroscience Institute, NYU Langone Medical Center, New York, NY, USA
| | - Bruce L McNaughton
- The Canadian Centre for Behavioural Neuroscience, University of Lethbridge, Lethbridge, AB, Canada
| | - Yitzhak Norman
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
- Department of Neurological Surgery, University of California, San Francisco, CA, USA
| | | | | | - Jon W Rueckemann
- Department of Physiology and Biophysics, Washington National Primate Center, University of Washington, Seattle, WA, USA
| | - John J Sakon
- Department of Psychology, University of Pennsylvania, Philadelphia, PA, USA
| | - Ivan Skelin
- Department of Neurology, Center for Mind and Brain, University of California Davis, Oakland, CA, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Stanford, CA, USA
| | - Bernhard P Staresina
- Department of Experimental Psychology, Oxford Centre for Human Brain Activity, Wellcome Centre for Integrative Neuroimaging, Department of Psychiatry, University of Oxford, Oxford, UK
| | - Shennan A Weiss
- Brookdale Hospital Medical Center, SUNY Downstate Medical Center, Brooklyn, NY, USA
| | - Matthew A Wilson
- Department of Brain and Cognitive Sciences and Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kareem A Zaghloul
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health, Bethesda, MD, USA
| | - Michaël Zugaro
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - György Buzsáki
- Department of Neurology, NYU Grossman School of Medicine, New York, NY, USA.
- Neuroscience Institute, NYU Langone Medical Center, New York, NY, USA.
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22
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Abstract
High-frequency oscillatory events, termed ripples, represent synchrony of neural activity in the brain. Recent evidence suggests that medial temporal lobe (MTL) ripples support memory retrieval. However, it is unclear if ripples signal the reinstatement of episodic memories. Analyzing electrophysiological MTL recordings from 245 neurosurgical participants performing episodic recall tasks, we find that the rate of hippocampal ripples rises just prior to the free recall of recently formed memories. This prerecall ripple effect (PRE) is stronger in the CA1 and CA3/dentate gyrus (CA3/DG) subfields of the hippocampus than the neighboring MTL regions entorhinal and parahippocampal cortex. PRE is also stronger prior to the retrieval of temporally and semantically clustered, as compared with unclustered, recalls, indicating the involvement of ripples in contextual reinstatement, which is a hallmark of episodic memory.
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23
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Camarillo-Rodriguez L, Leenen I, Waldman Z, Serruya M, Wanda PA, Herweg NA, Kahana MJ, Rubinstein D, Orosz I, Lega B, Podkorytova I, Gross RE, Worrell G, Davis KA, Jobst BC, Sheth SA, Weiss SA, Sperling MR. Temporal lobe interictal spikes disrupt encoding and retrieval of verbal memory: A subregion analysis. Epilepsia 2022; 63:2325-2337. [PMID: 35708911 DOI: 10.1111/epi.17334] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 11/29/2022]
Abstract
OBJECTIVE The medial temporal lobe (MTL) encodes and recalls memories and can be a predominant site for interictal spikes (IS) in patients with focal epilepsy. It is unclear whether memory deficits are due to IS in the MTL producing a transient decline. Here, we investigated whether IS in the MTL subregions and lateral temporal cortex impact episodic memory encoding and recall. METHODS Seventy-eight participants undergoing presurgical evaluation for medically refractory focal epilepsy with depth electrodes placed in the temporal lobe participated in a verbal free recall task. IS were manually annotated during the pre-encoding, encoding, and recall epochs. We examined the effect of IS on word recall using mixed-effects logistic regression. RESULTS IS in the left hippocampus (odds ratio [OR] = .73, 95% confidence interval [CI] = .63-.84, p < .001) and left middle temporal gyrus (OR = .46, 95% CI = .27-.78, p < .05) during word encoding decreased subsequent recall performance. Within the left hippocampus, this effect was specific for area CA1 (OR = .76, 95% CI = .66-.88, p < .01) and dentate gyrus (OR = .74, 95% CI = .62-.89, p < .05). IS in other MTL subregions or inferior and superior temporal gyrus and IS occurring during the prestimulus window did not affect word encoding (p > .05). IS during retrieval in right hippocampal (OR = .22, 95% CI = .08-.63, p = .01) and parahippocampal regions (OR = .24, 95% CI = .07-.8, p < .05) reduced the probability of recalling a word. SIGNIFICANCE IS in medial and lateral temporal cortex contribute to transient memory decline during verbal episodic memory.
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Affiliation(s)
| | - Iwin Leenen
- Faculty of Psychology, National Autonomous University of Mexico, Mexico City, Mexico
| | - Zachary Waldman
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Mijail Serruya
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Paul A Wanda
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nora A Herweg
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael J Kahana
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Daniel Rubinstein
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
| | - Iren Orosz
- Department of Neurology, University of California, Los Angeles, Los Angeles, California, USA
| | | | | | - Robert E Gross
- Department of Neurosurgery, Emory University, Atlanta, Georgia, USA
| | | | - Kathryn A Davis
- Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Barbara C Jobst
- Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA
| | - Sameer A Sheth
- Department of Neurological Surgery, Baylor College of Medicine, Houston, Texas, USA
| | - Shennan A Weiss
- Department of Neurology, State University of New York Downstate Medical Center, Brooklyn, New York, USA.,Department of Physiology and Pharmacology, State University of New York Downstate Medical Center, Brooklyn, New York, USA.,Departments of Neurology, New York City Health + Hospitals/Kings County, Brooklyn, New York, USA
| | - Michael R Sperling
- Department of Neurology, Thomas Jefferson University, Philadelphia, Pennsylvania, USA
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24
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Dubey M, Pascual-Garcia M, Helmes K, Wever DD, Hamada MS, Kushner SA, Kole MHP. Myelination synchronizes cortical oscillations by consolidating parvalbumin-mediated phasic inhibition. eLife 2022; 11:73827. [PMID: 35001871 PMCID: PMC8887893 DOI: 10.7554/elife.73827] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/28/2021] [Indexed: 12/18/2022] Open
Abstract
Parvalbumin-positive (PV+) γ-aminobutyric acid (GABA) interneurons are critically involved in producing rapid network oscillations and cortical microcircuit computations, but the significance of PV+ axon myelination to the temporal features of inhibition remains elusive. Here, using toxic and genetic mouse models of demyelination and dysmyelination, respectively, we find that loss of compact myelin reduces PV+ interneuron presynaptic terminals and increases failures, and the weak phasic inhibition of pyramidal neurons abolishes optogenetically driven gamma oscillations in vivo. Strikingly, during behaviors of quiet wakefulness selectively theta rhythms are amplified and accompanied by highly synchronized interictal epileptic discharges. In support of a causal role of impaired PV-mediated inhibition, optogenetic activation of myelin-deficient PV+ interneurons attenuated the power of slow theta rhythms and limited interictal spike occurrence. Thus, myelination of PV axons is required to consolidate fast inhibition of pyramidal neurons and enable behavioral state-dependent modulation of local circuit synchronization.
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Affiliation(s)
- Mohit Dubey
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | | | - Koke Helmes
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Dennis D Wever
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands
| | - Mustafa S Hamada
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands.,Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
| | - Steven A Kushner
- Department of Psychiatry, Erasmus Medical Centre, Rotterdam, Netherlands
| | - Maarten H P Kole
- Department of Axonal Signaling, Netherlands Institute for Neuroscience (NIN), Royal Netherlands Academy of Arts and Sciences (KNAW), Amsterdam, Netherlands.,Cell Biology, Neurobiology and Biophysics, Department of Biology, Faculty of Science, Utrecht University, Utrecht, Netherlands
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25
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Gotman J. How Epileptic Spikes Impair Memory. Epilepsy Curr 2021; 22:31-32. [PMID: 35233193 PMCID: PMC8832348 DOI: 10.1177/15357597211051940] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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26
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Norman Y, Raccah O, Liu S, Parvizi J, Malach R. Hippocampal ripples and their coordinated dialogue with the default mode network during recent and remote recollection. Neuron 2021; 109:2767-2780.e5. [PMID: 34297916 DOI: 10.1016/j.neuron.2021.06.020] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 05/13/2021] [Accepted: 06/16/2021] [Indexed: 12/19/2022]
Abstract
Hippocampal ripples are prominent synchronization events generated by hippocampal neuronal assemblies. To date, ripples have been primarily associated with navigational memory in rodents and short-term episodic recollections in humans. Here, we uncover different profiles of ripple activity in the human hippocampus during the retrieval of recent and remote autobiographical events and semantic facts. We found that the ripple rate increased significantly before reported recall compared to control conditions. Patterns of ripple activity across multiple hippocampal sites demonstrated remarkable specificity for memory type. Intriguingly, these ripple patterns revealed a semantization dimension, in which patterns associated with autobiographical contents become similar to those of semantic memory as a function of memory age. Finally, widely distributed sites across the neocortex exhibited ripple-coupled activations during recollection, with the strongest activation found within the default mode network. Our results thus reveal a key role for hippocampal ripples in orchestrating hippocampal-cortical communication across large-scale networks involved in conscious recollection.
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Affiliation(s)
- Yitzhak Norman
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
| | - Omri Raccah
- Laboratory of Behavioral and Cognitive Neuroscience, Stanford Human Intracranial Cognitive Electrophysiology Program, Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Su Liu
- Laboratory of Behavioral and Cognitive Neuroscience, Stanford Human Intracranial Cognitive Electrophysiology Program, Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Josef Parvizi
- Laboratory of Behavioral and Cognitive Neuroscience, Stanford Human Intracranial Cognitive Electrophysiology Program, Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Rafael Malach
- Department of Neurobiology, Weizmann Institute of Science, Rehovot 76100, Israel.
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