Spectral analysis of seizures in humans

Tharp, Barry R.; Gersch, Will

doi:10.1016/0010-4809(75)90023-3

Cited by 37 publications

(6 citation statements)

References 17 publications

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“…The application of coherence analysis for investigating linear relations among multichannel EEG was first described by Walter and Adey (49). Since then, coherence and phase analysis has been used by various investigators, including Brazier, Tharp, and Gersch (47,50) among others, to trace the spread of seizure activity in human patients. In patients without epilepsy, Tucker et al (35) exploited both partial and partialmultiple coherence techniques in ascertaining the level of within-hemisphere associations during the performance of cognitive tasks.…”

Section: Discussionmentioning

confidence: 99%

Anterior Thalamic Mediation of Experimental Seizures: Selective EEG Spectral Coherence

Mirski

Tsai

Rossell³

et al. 2003

Epilepsia

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Summary:Purpose: Physiological evidence has shown that the anterior thalamus (AN) and its associated efferents/ afferents constitute an important propagation pathway for pentylenetetrazol (PTZ)-mediated generalized seizures in rodents. Previous work demonstrated metabolic, physical, chemical, and electrical stimulation data supporting a role for AN in the expression of PTZ seizures. We now extend these observations through examination of neuroelectric signal indicators during seizure epochs. We show that the EEG recorded from AN is highly coherent with surface cortical (CTX) EEG during the immediate preconvulsant period and during the ictal stateough.Methods: Awake rats were continuously infused with PTZ until clonic seizures were recorded by using both subcortical AN, posterior thalamus (PT), or hippocampal (HPC) bipolar electrodes and cortical EEG. Through the signal-analysis techniques of ordinary and partial coherence, it was possible to focus selectively on signal correlations between AN and CTX (AN/CTX) by removing the effects of unaffiliated regions such as PT and HPC.Results: Coherence of PT/CTX was observed to be modest, and partial coherence of PT/CTX with the effects of AN/CTX removed did not improve the signal coherence of PT/CTX (PT/ CTX-AN). In contrast, AN/CTX coherence was observed to be high, with undiminished correlation when PT/CTX influence was removed (AN/CTX-PT). The most robust band of AN/ CTX coherence was centered around the spike-wave clonic frequency of 1-3 Hz. Partial multiple coherence-analysis techniques were used to remove the possible signal contributions from hippocampus in addition to PT. The AN/CTX coherence remained fully preserved in the low-frequency bands.Conclusions: These data provide electrophysiologic evidence supporting the special role of the anterior thalamus in the propagation of seizure activity between subcortex and cortex. Key Words: Anterior thalamus-EEG-Coherence-Seizure-Pentylenetetrazol.The precise neuronal pathways underlying the propagation and generalization of epileptic seizure activity remain largely unknown (1-6). Numerous studies have been performed to analyze the electrophysiology of focal cortical and hippocampal epileptic foci, and the local spread of these electrical paroxysms (7-10). Identification of specific cortical-subcortical pathways mediating seizure propagation between deep and surface neuronal elements has yet remained elusive, despite studies supporting the contribution of deep brain regions in clinical and EEG seizure expression (1-6). Mapping such connectivity would greatly improve our understanding of seizure mechanisms on a systems level, and offer potential sites for target-specific therapy, such as deep brain stimulation.Previously we established that the thalamic anterior nuclear complex (AN), a thalamic element of the limbic system, is an important gating center for the propagation of pentylenetetrazol (PTZ) seizure activity (11-15). Experiments supporting the hypothesis of AN mediation of convulsive activity include selective up...

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Section: Discussionmentioning

confidence: 99%

Anterior Thalamic Mediation of Experimental Seizures: Selective EEG Spectral Coherence

Mirski

Tsai

Rossell³

et al. 2003

Epilepsia

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“…Previous investigations using power spectral analysis in the evaluation of epileptic EEG activity have been directed generally to localization of pathology and differential diagnosis (Binnie et al, 1978;Macgillivray , 1977) and more specifically to particular EEG components (Taistra et al, 1976) or the spread of ictal discharge (Brazier, 1972; Tharp and Gersch, 1975). The application of power spectral analysis here sought, instead, to compare matched nonepileptic and epileptic subjects in terms of normal sensorimotor EEG frequency components, for which neurophysiological substrates could be implied, in an effort to identify common elements of neuropathology.…”

Section: Discussionmentioning

confidence: 99%

Power Spectral Analysis of EEG Characteristics During Sleep in Epileptics

Sterman¹

1981

Epilepsia

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Power spectral analysis of spontaneous EEG activity recorded during non-rapid eye movement (REM) sleep was employed in an effort to identify characteristic EEG substrate abnormalities in epileptics. All-night polygraphic recordings were obtained from 10 poorly controlled subjects with mixed and generalized seizures. Similar data were obtained from 10 matched nonepileptic subjects. Continuous 10 min samples of non-REM sleep were identified at the beginning and end of these all-night recordings. EEG activity recorded during these periods from left sensorimotor and parieto-occipital bipolar leads was digitized, subjected to the fast Fourier transform, and then sorted into successive 4 Hz frequency bands between 0 and 23 Hz. Mean spectral density was determined for each frequency band from both samples in both groups. Comparison of these values disclosed both similarities and differences between the two groups. All subjects showed a significant "time-of-night effect," with power at 0-3, 4-7, and 8-11 Hz greater at the beginning of the night. This finding was related to a similar observation in developing infants and attributed to a circadian influence on neuronal generators. In group comparisons, epileptics showed selective differences in common when compared with nonepileptics. These differences were reduced when data from a small group of unmedicated epileptic subjects were partialled out. Medicated epileptics showed differences restricted to the early morning non-REM sleep sample, which included significantly greater power at 4-7 Hz and significantly lower power at 12-15 Hz. Unmedicated subjects showed these differences in both samples and also showed significantly greater power in the 0-3 Hz band. It was suggested that anticonvulsant medications may exert a general normalizing influence on EEG characteristics during sleep, particularly at the beginning of the night in proximity to their administration. The documentation of significant EEG deviations restricted to two basic rhythmic patterns during sleep suggests a disturbance of underlying thalamocortical mechanisms.

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“…These values were used in subsequent statistical procedures (Student's t test; P < 0.05 taken to indicate significance) to test whether the coherences were significantly different from zero and whether the partialization had a significant effect and also for comparison of group means (Gersch & Goddard, 1970;Lopes da Silva, Vos, Mooibroek & Van Rotterdam, 1980). For conclusions concerning the relationship between nerve discharge and blood pressure, more robust criteria (Tharp & Gersch, 1975) were used. The level of functionally effective 'significant' baroreceptor influence (0 5) was determined on the basis of the distribution of this variable over the sample of eighty-one nerves (see below).…”

Section: Methodsmentioning

confidence: 99%

Baroreceptor influence on the relationships between discharges of different sympathetic nerves of the cat.

Kocsis¹

1995

The Journal of Physiology

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1. The sympathetic nerve discharge (SND) of three different nerves and the arterial blood pressure (BP) were recorded simultaneously in baroreceptor-intact cats. The linear correlation between different nerve pairs was characterized by the coherence spectrum and its baroreceptor-related component was estimated by partialization of the coherence on the basis of the blood pressure signal. 2. The SND-SND coherence values were higher than those found earlier in baroreceptordenervated cats. As shown by partial coherence analysis, in about 50 % of the experiments with high SND-BP coherence (25 nerve pair recordings), this could be explained by superposition of the effects of common central sources of activity and of the additional common rhythmic input from the baroreceptors. Partialization was ineffective in 50 % of the experiments with high SND-BP coherence (22 nerve pairs) and also when the SND-BP coherence was relatively low (17 nerve pairs). On the group average, after elimination of the components explained by baroreceptor influence, the peak SND-SND coherence no longer correlated with the SND-BP coherence and both the numerical values and the relative pattern of coherences between different nerves became similar to those characteristic for baroreceptor-denervated cats. 3. It is suggested that the method used in this study represents a 'theoretical barodenervation' and may be of great value in experiments, when surgical or chemical denervation of the baroreceptors does not represent a real option, e.g. in human subjects.

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Spectral analysis of seizures in humans

Cited by 37 publications

References 17 publications

Anterior Thalamic Mediation of Experimental Seizures: Selective EEG Spectral Coherence

Anterior Thalamic Mediation of Experimental Seizures: Selective EEG Spectral Coherence

Power Spectral Analysis of EEG Characteristics During Sleep in Epileptics

Baroreceptor influence on the relationships between discharges of different sympathetic nerves of the cat.

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