scholarly journals The penetration of plasma clouds across magnetic boundaries: The role of high frequency oscillations

2004 ◽  
Vol 11 (7) ◽  
pp. L33-L36 ◽  
Author(s):  
Tomas Hurtig ◽  
Nils Brenning ◽  
Michael A. Raadu
Keyword(s):  
High Frequency ◽  
High Frequency Oscillations

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.

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.

The role of high frequency oscillations in the penetration of plasma clouds across magnetic boundaries

2005 ◽  
Vol 12 (1) ◽  
pp. 012308 ◽  
Author(s):  
Tomas Hurtig ◽  
Nils Brenning ◽  
Michael A. Raadu
Keyword(s):  
High Frequency ◽  
High Frequency Oscillations

scholarly journals Role of High Frequency Oscillations of Somatosensory Evoked Potentials in Deciphering Pathophysiology of Migraine

2020 ◽  
Author(s):  
Abhinandan K. Shankar ◽  
Mahendra Javali ◽  
Anish Mehta ◽  
R. Pradeep ◽  
Rohan Mahale ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
High Frequency ◽  
Peak Amplitude ◽  
High Frequency Oscillations ◽  
Sophisticated Method ◽  
Indian Context ◽  
Band Pass ◽  
Zero Phase ◽  
Excitatory Drive

Abstract Background Habituation deficit is considered as a neurophysiological abnormality among migraineurs in the interictal period. For clear comprehension and clarity about the mechanism underlying habituation in migraine, a sophisticated method, i.e., high frequency oscillations (HFOs) evoked potentials, have been utilized. However, studies pertaining to this in the Indian context are rare. Objective The aim of the study is to determine the utility of HFO of somatosensory evoked potential (SSEP) in deciphering the pathophysiology of migraine. Materials and Methods Sixty subjects including 30 migraineurs in the interictal period and 30 healthy controls were considered for the study. Median nerve SSEP was recorded in patients and controls by standard protocols. HFO was extracted offline using the Digital zero-phase shift band-pass filtering at 450 and 750 Hz. The early and late HFOs were determined with respect to the N20 peak and were compared between the groups. Results Of total 30 migraineurs, 18 had hemicranial headache and 12 had holocranial headache. N20 latency, P25 latency, N20 onset to peak amplitude, and N20 onset to P25 amplitude were comparable in migraineurs and controls. The intraburst frequency of early HFOs in migraineurs was significantly higher (p = 0.04), whereas the peak-to-peak amplitude was significantly lower (p = 0.001). Conclusion Early HFOs on SSEP represent the thalamocortical excitatory drive in migraineurs. Overall, the study reports that reduced amplitude of early HFOs in the interictal period suggest reduced thalamocortical drive in migraineurs.

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