scholarly journals The Oscillatory Basis of Working Memory Function and Dysfunction in Epilepsy

2021 ◽  
Vol 14 ◽  
Author(s):  
Olivia N. Arski ◽  
Julia M. Young ◽  
Mary-Lou Smith ◽  
George M. Ibrahim
Keyword(s):  
Working Memory ◽  
High Frequency ◽  
Large Scale ◽  
Memory Function ◽  
Epileptic Activity ◽  
Functional Roles ◽  
High Frequency Oscillations ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges

Working memory (WM) deficits are pervasive co-morbidities of epilepsy. Although the pathophysiological mechanisms underpinning these impairments remain elusive, it is thought that WM depends on oscillatory interactions within and between nodes of large-scale functional networks. These include the hippocampus and default mode network as well as the prefrontal cortex and frontoparietal central executive network. Here, we review the functional roles of neural oscillations in subserving WM and the putative mechanisms by which epilepsy disrupts normative activity, leading to aberrant oscillatory signatures. We highlight the particular role of interictal epileptic activity, including interictal epileptiform discharges and high frequency oscillations (HFOs) in WM deficits. We also discuss the translational opportunities presented by greater understanding of the oscillatory basis of WM function and dysfunction in epilepsy, including potential targets for neuromodulation.

scholarly journals High-frequency oscillations detected by electroencephalography as biomarkers to evaluate treatment outcome, mirror pathological severity and predict susceptibility to epilepsy

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Yueqian Sun ◽  
Guoping Ren ◽  
Jiechuan Ren ◽  
Qun Wang
Keyword(s):  
Treatment Outcome ◽  
High Frequency ◽  
Large Scale ◽  
Clinical Applications ◽  
The Past ◽  
Scalp Eeg ◽  
High Frequency Oscillations ◽  
Potential Biomarker ◽  
Epileptic Patients

AbstractHigh-frequency oscillations (HFOs) in the electroencephalography (EEG) have been extensively investigated as a potential biomarker of epileptogenic zones. The understanding of the role of HFOs in epilepsy has been advanced considerably over the past decade, and the use of scalp EEG facilitates recordings of HFOs. HFOs were initially applied in large scale in epilepsy surgery and are now being utilized in other applications. In this review, we summarize applications of HFOs in 3 subtopics: (1) HFOs as biomarkers to evaluate epilepsy treatment outcome; (2) HFOs as biomarkers to measure seizure propensity; (3) HFOs as biomarkers to reflect the pathological severity of epilepsy. Nevertheless, knowledge regarding the above clinical applications of HFOs remains limited at present. Further validation through prospective studies is required for its reliable application in the clinical management of individual epileptic patients.

scholarly journals ANALYSIS OF THE FUCTIONAL ROLE OF RICE MILLING COMPANY ON THE WELFARE OF RICE FARMERS IN THE SUB-DISTRICT BUAY MADANG TIMUR DISTRICT OKU TIMUR

Jurnal AKTUAL ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 47
Author(s):  
Aisah Aisah
Keyword(s):  
Large Scale ◽  
Raw Materials ◽  
Small Scale ◽  
Functional Roles ◽  
Medium Scale ◽  
Rice Farmers ◽  
Result Show ◽  
Rice Milling ◽  
Processing And Storage

Rice Milling Company is rice industry’s oldest and largest classified in Indonesia, which is able to absorb more than 10 million workers, handles more than 40 million tons of grain.  Rice Milling Company agro-industy is the central point, because this is where the main product is obtained in the form of rice and raw materials for advanced processing of food and industrial products.  Rice Miling Unit in the district of OKU Timur there is some skala, ranging form small-scale, medium-scale to large-scale.  Fuctional benefits of each different scale milling is also different.  The average rice farmers often sell gabahnya to the rice milling unit closest to the place residence, whether it is large-scale, medium and small.  Rice produced by the milling-grinding different quality.  Usually when a large-scale millimg yield of rice is cleaner than the other scale.  But it does not become a reference for milling grain milling usually depends on consumer demand.  The purpose of the study are : 1.  To determine levels of volume (tonnage) and the retention time of each service fuctional rice storage (barns) wich carried a different scale rice milling unit.  2.  To determine differences in the bebefits of economic transactions received by farmers and rice millers of different scale of business, especially when seen from the level of the milling costs, the purchase price of rice by rice milling unit, and the quality of milling services and service scale.  The result show that : the fuctional role of each is different milling.  Large-scale milling has three fuctional roles are : Processing, storage and distribution.  Medium-scale miling functional has two roles, namely : processing and distribution.  While small-scale rice milling unit has only two functional roles are : processing and storage.

Cognitive refractory state caused by spontaneous epileptic high-frequency oscillations in the human brain

2019 ◽  
Vol 11 (514) ◽  
pp. eaax7830 ◽  
Author(s):  
Su Liu ◽  
Josef Parvizi
Keyword(s):  
Cognitive Deficits ◽  
High Frequency ◽  
Medial Temporal Lobe ◽  
Memory Performance ◽  
Physiological Responses ◽  
Epileptic Activity ◽  
Epileptic Focus ◽  
Surgical Removal ◽  
High Frequency Oscillations ◽  
Refractory State

Epileptic brain tissue is often considered physiologically dysfunctional, and the optimal treatment of many patients with uncontrollable seizures involves surgical removal of the epileptic tissue. However, it is unclear to what extent the epileptic tissue is capable of generating physiological responses to cognitive stimuli and how cognitive deficits ensuing surgical resections can be determined using state-of-the-art computational methods. To address these unknowns, we recruited six patients with nonlesional epilepsies and identified the epileptic focus in each patient with intracranial electrophysiological monitoring. We measured spontaneous epileptic activity in the form of high-frequency oscillations (HFOs), recorded stimulus-locked physiological responses in the form of physiological high-frequency broadband activity, and explored the interaction of the two as well as their behavioral correlates. Across all patients, we found abundant normal physiological responses to relevant cognitive stimuli in the epileptic sites. However, these physiological responses were more likely to be “seized” (delayed or missed) when spontaneous HFOs occurred about 850 to 1050 ms before, until about 150 to 250 ms after, the onset of relevant cognitive stimuli. Furthermore, spontaneous HFOs in medial temporal lobe affected the subjects’ memory performance. Our findings suggest that nonlesional epileptic sites are capable of generating normal physiological responses and highlight a compelling mechanism for cognitive deficits in these patients. The results also offer clinicians a quantitative tool to differentiate pathological and physiological high-frequency activities in epileptic sites and to indirectly assess their possible cognitive reserve function and approximate the risk of resective surgery.

scholarly journals Interictal epileptiform discharges shape large-scale intercortical communication

Brain ◽  
2019 ◽  
Vol 142 (11) ◽  
pp. 3502-3513 ◽  
Author(s):  
Prawesh Dahal ◽  
Naureen Ghani ◽  
Adeen Flinker ◽  
Patricia Dugan ◽  
Daniel Friedman ◽  
...  
Keyword(s):  
Large Scale ◽  
Focal Epilepsy ◽  
Brain Dysfunction ◽  
Normal Brain ◽  
Brain Rhythms ◽  
Epileptiform Discharges ◽  
Interictal Epileptiform Discharges

Focal epilepsy is associated with large-scale brain dysfunction. Dahal et al. reveal that interictal epileptiform discharges modulate normal brain rhythms in regions beyond the epileptic network, potentially impairing processes that rely heavily upon intercortical communication, such as cognition and memory.

scholarly journals High-frequency oscillations in human and monkey neocortex during the wake–sleep cycle

2016 ◽  
Vol 113 (33) ◽  
pp. 9363-9368 ◽  
Author(s):  
Michel Le Van Quyen ◽  
Lyle E. Muller ◽  
Bartosz Telenczuk ◽  
Eric Halgren ◽  
Sydney Cash ◽  
...  
Keyword(s):  
High Frequency ◽  
Large Scale ◽  
Microelectrode Array ◽  
Slow Wave Sleep ◽  
Inhibitory Neurons ◽  
Sleep Cycle ◽  
High Frequency Oscillations ◽  
Wake Patterns ◽  
Fast Oscillations ◽  
Array Recordings

Beta (β)- and gamma (γ)-oscillations are present in different cortical areas and are thought to be inhibition-driven, but it is not known if these properties also apply to γ-oscillations in humans. Here, we analyze such oscillations in high-density microelectrode array recordings in human and monkey during the wake–sleep cycle. In these recordings, units were classified as excitatory and inhibitory cells. We find that γ-oscillations in human and β-oscillations in monkey are characterized by a strong implication of inhibitory neurons, both in terms of their firing rate and their phasic firing with the oscillation cycle. The β- and γ-waves systematically propagate across the array, with similar velocities, during both wake and sleep. However, only in slow-wave sleep (SWS) β- and γ-oscillations are associated with highly coherent and functional interactions across several millimeters of the neocortex. This interaction is specifically pronounced between inhibitory cells. These results suggest that inhibitory cells are dominantly involved in the genesis of β- and γ-oscillations, as well as in the organization of their large-scale coherence in the awake and sleeping brain. The highest oscillation coherence found during SWS suggests that fast oscillations implement a highly coherent reactivation of wake patterns that may support memory consolidation during SWS.

scholarly journals ANALYSIS OF HIGH-RESOLUTION MICROELECTRODE EEG RECORDINGS IN AN ANIMAL MODEL OF SPONTANEOUS LIMBIC SEIZURES

2009 ◽  
Vol 19 (02) ◽  
pp. 605-617 ◽  
Author(s):  
C. KOMALAPRIYA ◽  
M. C. ROMANO ◽  
M. THIEL ◽  
U. SCHWARZ ◽  
J. KURTHS ◽  
...  
Keyword(s):  
Animal Model ◽  
High Resolution ◽  
High Frequency ◽  
Recurrence Time ◽  
Very High Frequency ◽  
Limbic Seizures ◽  
High Frequency Oscillations ◽  
Quantification Analysis ◽  
Eeg Recordings

We perform a systematic data analysis on high resolution (0.5–12 kHz) multiarray microelectrode recordings from an animal model of spontaneous limbic epilepsy, to investigate the role of high frequency oscillations and the occurrence of early precursors for seizures. Results of spectral analysis confirm the importance of very high frequency oscillations (even greater than 600 Hz) in normal (healthy) and abnormal (epileptic) hippocampus. Furthermore, we show that the measures of Recurrence Quantification Analysis (RQA) and Recurrence Time Statistics (RTS) are successful in indicating, rather uniquely, the onset of ictal state and the occurrence of some warnings/precursors during the pre-ictal state, in contrast to the linear measures investigated.

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