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Biomedical subjects

H Petsche

Publications and source records attributed to H Petsche.

At least 55 records · Page 3Linked to original sources
PubMed1977

[The phenomenon of synchronization in the status epilepticus produced by penicillin and its changes after Clonazepam (author's transl)].

The purpose of this series of experiments was to understand how Clonazepam changes the mechanisms of synchronization in seizures. Penicillin was applied to the rabbits cortex. Interictal spikes and seizures were recorded with multiple electrodes from both the cortical surface and intracortically. The spatio-temporal relationships during these electrical events were studied by topographical methods. Moreover, power spectrum and coherence estimates were performed. A most characteristic feature seen with low doses of Clonazepam is a regularization of the spatio-temporal behaviour of both spikes and seizures. The number of tonic phases considerably increases at the cost of clonic phases. The seizures take more time to become generalized. The generator-zones become larger. This is explained by a decrease of the number of neurones--by Clonazepam--which are still left to produce "paroxysmal depolarization shifts". The findings confirm the increase of postsynaptic cortical inhibition under Clonazepam, as demonstrated by various authors.

Animals↗
PubMed1976

Topography of the EEG: survey and prospects.

In the first part of the paper the purpose and aims of topographical approach to the understanding of the EEG are set out. Since the EEG is not identical with the electrical activity recorded directly from its generator layer, the neocortex, topographic methods applied to the human EEG recorded from the scalp are somewhat less informative than in experimental work on the exposed brain. The paper gives a brief historical survey of the most essential attempts in this field throughout the history of electroencephalography. After this, a few promising methods now in use, and their possible fields of application, are demonstrated. The paper ends with a view of the future.

Alpha Rhythm↗
PubMed1976

[Intracortical electrogenesis: spontaneous activity, sleep and epileptic seizure (author's transl)].

Various electrical activities were recorded in rabbits from within the cortex by means of a multielectrode carrying, on a glass needle, 8 Ag-AgCl contacts (50X50 micronm) at 300 micronm distances. The records were stored on tape and analyzed (power spectrum, coherence and phase). Generally, the relatively uniform pattern of the cortical surface is paralleled by a spatio-temporally very complex intracortical activity. In all activities a zone of minimum activity ("zero zone") was found between roughly 500 and 800 micronm below surface. Beyond this zone, activities often appear like a mirrorimage of the surface activities although true phase-reversals never occur. In spontaneous activities this zone remains constant, during seizures it may shift and broaden. The maximum power is usually found below this zone. The transcortical power profile often changes during seizures. Tonic patterns, although fairly uniform in the ECoG from the surface of the cortex, turn out to be composed of several components when studied intracortically. The "generator zones" of the various intracortically identifiable graphoelements have various vertical position and extension. These findings demonstrate that a certain neuronal circuitry may be responsible for the shape of the potential recorded. This circuitry is far from rigid but may change in different stages of synchronization. For a better spatio-temporal resolution of intracortical activities, the interelectrode distance has still to be reduced.

Animals↗