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H Petsche

Publications and source records attributed to H Petsche.

At least 37 records · Page 2Linked to original sources
PubMed1985

On-going EEG in depression: a topographic spectral analytical pilot study.

Spontaneous EEG activities recorded with 19 electrodes (10-20 system) on the scalp were quantified by spectral analytical methods (power and coherence spectra) to reveal changes of power and coherence during different conditions (eyes closed/relaxed, eyes opened/relaxed, flicker stimulation, reading, listening to a story). Control subjects and depressive patients were compared. Power as well as coherence changes were found in all frequency bands. Changes in the organization of the EEG were found in different areas of both hemispheres. The EEG organization was different in control subjects and depressive patients, indicating different levels of vigilance and/or different cognitive strategies in verbal tasks in the two groups.

Adult↗
PubMed1985

[Music perception, EEG and musical training].

Changes of EEG during listening to music were studied in two groups of probands, one of them with several years of training on a musical instrument. The EEG was recorded simultaneously from 19 electrodes (10:20 system) against connected ear lobe electrodes. One minute recording periods at rest before and after music were compared with a period of one minute recording during listening to music. 30 seconds of each of these recordings were studied by Fourier analysis. Averaged power and coherence spectra (between transversally adjacent electrodes and between electrodes on homologous regions of both hemispheres) were computed. Broad band parameters were chosen for 5 frequency bands between 4 and 32 Hz. Significant changes of the parameters were represented topographically. During listening to music, a significant reversible decrease of the parameters studied was found: in the musically trained group on both sides, but preponderantly on the right hemisphere, in the non-trained group almost exclusively on the left hemisphere. Moreover, in the trained group, the changes occurred more frequently and involved larger regions of the skull than in the untrained group. In addition, the first group had most changes in the frequency range between 18 and 24 Hz, the second group between 13 and 18 Hz. Finally, comparisons of the changes between the control period before music and music and those between the control period after music and listening to music led to additional conclusions on different strategies of the processing of musical information in musically trained and untrained persons.

Adult↗
PubMed1984

Penicillin-induced epileptic phenomena in the rabbit's neocortex I. The development of interictal spikes after epicortical application of penicillin.

In an attempt to elucidate the generation mechanisms underlying interictal spikes in the neocortex, the temporal development of spikes after the epicortical penicillin (PNC) application was studied. Field potentials (FP) were recorded simultaneously within the 6 neocortical layers with a multielectrode consisting of 16 contacts (10 X 10 micron 2) in a row at spacings of 150 micron. A one-dimensional current-source-density (CSD) analysis yielded the positions of current, sink and source densities, so that the different electrical events during a spike could be more accurately located within the different neocortical layers. After the epicortical application of PNC a typical succession of events, which underly the development of spikes, was observed. These events are similar in the visual and the motor cortex: immediately after the epicortical PNC application negative transients occur in the two uppermost cortical layers as well as within layers V to III. Due to the diffusion of the drug a characteristic succession of different processes takes place. Fully developed spikes show a typical configuration of sources and sinks, a moderate sink in layer V initiates a massive, double-peaked sink within layers II, III. This configuration of sinks suggests that some sort of triggering mechanism takes place. Since similar events are observed during interictal spikes in the visual and the motor cortex, neuronal structures common to both cortical areas are supposed to be responsible for the generation of PNC spikes.

Animals↗
PubMed1984

Penicillin-induced epileptic phenomena in the rabbit's neocortex II. Laminar specific generation of interictal spikes after the application of penicillin to different cortical depths.

To elucidate the generation mechanisms of interictal spikes we analyzed the electrical events in the different layers of the rabbit's neocortex after application of penicillin to distinct cortical layers. Field potentials (FP) recorded simultaneously from all layers with a 16-fold micro-electrode-assembly were subjected to current-source-density analysis (CSD), which allows a more accurate description of local electrical events. To demonstrate the influence of neocortical architectonics on the generation of interictal spikes, 3 different areas-area occipitalis 1, precentralis 1 and 2, according to Fleischhauer et al., were studied. Interictal spikes develop regardless of the depth of PNC application. Moreover the appearance of spikes does not seem to depend exclusively on the diffusion of PNC into a distinct cortical layer (i.e. layers IV and V). The CSD analysis indicated that different generation mechanisms within the different cortical layers underly the spikes. According to CSD configurations maximum sinks occur at depths where the dendrites join closely to form bundles. This finding supports the importance of dendrites for the generation of interictal spikes. Finally, the distribution of CSD patterns is similar in all 3 neocortical areas studied, if PNC is applied to the same cortical depth.

Animals↗
PubMed1984

Computer-assisted EEG topography as a tool in the evaluation of actions of psychoactive drugs in patients.

This paper summarizes a tentative application of EEG topography to the evaluation of the efficiency of psychoactive drugs. It shows that the spectral content of the EEG, recorded simultaneously at different locations according to the international 10-20 system, is a sensitive measure for the quantification of drug activity. Furthermore, coherence analysis reveals differences in the functional organization of the neocortex under neuroleptic drug therapy.

Antipsychotic Agents↗
PubMed1983

Chandelier neurons within the rabbits' cerebral cortex. A Golgi study.

This study has been carried out by light microscopy on 3 Golgi-Kopsch impregnated brains of young adult rabbits. It is shown that chandelier cells exist within the rabbits' cerebral cortex. In the rabbit, the chandelier cell is a medium ranged bipolar interneuron in layer II/III with a characteristic axon which forms a plexus with a diameter of about 350-500 micrometers in the horizontal and 200-350 micrometers in the vertical direction; the end of each ramulus forms the typical "candlestick", a little vertical string of 1-6 boutons on an axon fibre. These boutons form contacts with all parts of pyramidal cells in layer II and the upper part of layer III. Similarities and differences with respect to previous descriptions of these cells in other species are discussed.

Animals↗
PubMed1982

The contribution of the cortical layers to the generation of the EEG: field potential and current source density analyses in the rabbit's visual cortex.

Intracortical spontaneous field potentials (EEG) were simultaneously recorded from the different layers of the rabbit's visual cortex using multielectrodes produced by thin-film technology. The signals were subjected to spectral analyses. Additionally, current source density analysis was applied to spontaneous delta waves. The results are based on 10 experiments. The spontaneous EEG of the rabbit's visual cortex consists mainly of slow delta waves. The spectral analytical studies of the delta band showed maximum power in layers I and II and in layers V and VI. Significant power minima were found in the middle layers IV and/or III. Essentially, the zones of power minima agree with the zones of minimum coherence and those zones where a phase reversal is observed. These properties of the intracortical spontaneous delta activity are best described as dipole-like. The spontaneous delta waves can be surface negative or surface positive; accordingly they show different source-sink distributions from which different generation mechanisms can be inferred. The possible mechanisms for the generation of these current source-sink distributions (dipoles) are discussed, taking into consideration the cortical anatomy. In many cases these discussions must be speculative because, for an unambiguous explanation of the observed phenomena, a much better knowledge of the cortical anatomy, the fibre connections with other cortical anatomy, the fibre connections with other cortical areas and with the deep cerebral structures is necessary.

Alpha Rhythm↗
PubMed1981

Current source density analysis: methods and application to simultaneously recorded field potentials of the rabbit's visual cortex.

This paper deals with the application of current source density (CSD) analysis to simultaneously recorded intracortical field potentials of the rabbit's visual cortex. Recordings were made with multielectrodes with either 8 contacts at distances of 300 microns, or 16 contacts at distances of 150 microns on one carrier needle. For synchronized activities, a spatial resolution of 150 microns turned out to be sufficient to record all depth-varying details of the field potentials; for seizure potentials even a spacing of 300 microns was adequate in most cases. For practical application, an appropriate spacing of the measuring points has to be chosen for a satisfactory estimation of the first and second derivatives of the field potentials. For this reason an interpolation procedure is applied to reduce the spacing from 300 microns or 150 microns electrode contact distances, respectively, and to obtain intermediate values at 75 microns distances. With this spacing satisfactory estimations of the second derivative are obtained. Theoretically, CSD analysis has to be made three-dimensionally, but under certain conditions which are discussed, a one-dimensional analysis can be applied. An unknown quantity is sigma z, the vertical conductivity. It turned out that average values obtained from different experiments are not representative and that the vertical conductivity has to be measured in every experiment. This is caused by the great individual differences of the cortices even if the same stereotactic coordinates are chosen. Therefore, in every experiment relative conductivity measurements are performed. The influence of different conductivity values within the various layers and the influence of a conductivity gradient is discussed and demonstrated by examples.

Animals↗
PubMed1981

[The effect of clonazepam on visual evoked potentials of the rabbit (author's transl)].

This paper deals with the action of Clonazepam on the cortical responses to visual stimuli in the rabbit. Epicortical as well as intracortical recordings from the different laminae were made by means of a multi-electrode made by thin film technology (13). Clonazepam was given intravenously in a dosis of 0.5 or 1.0 mg/kg body weight. The surface recordings showed that the visual evoked potentials (VEP) was, under the influence of the drug, altered only with respect to its secondary components. Those components which seem to originate within the zone of bilateral projection from both eyes are mostly influenced. The long lasting surface negative late component of the VEP was abolished by the action of the drug, and low-amplitude oscillations were seen instead. Within the different laminae of the visual cortex all components were altered in amplitude and latency. This phenomenon was most prominent within the zone of bilateral projection. Instead of two major negative components in the deep cortical layers, many positive and negative peaks were observed after the application of Clonazepam. This corresponds partly with the findings on the surface of the cortex. These results are discussed with respect to the manyfold mechanisms of action of Clonazepam.

Animals↗
PubMed1981

[Influence of clonazepam on interictal penicillin-spikes (author's transl)].

This paper deals with the action of Clonazepam on Penicillin induced interictal discharges. In 7 rabbits Penicillin was applied epicortically in a concentration of 25,000 or 50,000 I.U. The intracortical recordings were made with an 8 fold electrode, made by thin-film technology. Clonazepam (0.5 or 1.0 mg/kg) was given intravenously 30 to 45 min after the Penicillin application. Under Clonazepam the occurrence of double-und multiple interictal discharge is abolished. Single spikes become shorter and are significantly reduced in amplitude. Current Source-Density analysis showed that the configuration of sources and sinks is not altered under the action of this drug. However the spatio-temporal distribution is reduced drastically. If the shape of interictal spikes is compared by means of averaging technique before and after the application of Clonazepam, one observes a significant decrease in the standard deviation. These results indicate that excitatory processes are reduced by an enhancement of inhibitory phenomena within the cerebral cortex.

Animals↗
PubMed1978

[Neurophysiology of epileptic seizures (author's transl)].

The paper is a review of the progress made over the past years in the understanding of electrical processes occurring during epileptic seizures as elicited by the local application of penicillin. The events at the cellular level of the neocortex are discussed, as well as cortico-subcortical relationships and microtopography of the seizure patterns. The increased excitability under penicillin induces a great number of feedback processes, the electrical effects of which become visible in the seizure EEG with its high degree of organization. Neocortical architectonics is of great importance for the shape of the potentials and their distribution. Seizure patterns of different shape are found in the different layers of the cortex.

Animals↗
PubMed1978

EEG synchronization in seizures: facts and models.

In topographic studies of seizure patterns in the rabbit, the phenomenon of synchronization has turned out to be characterized by regular propagation of the potential fields underlying the raphoelements observed in the EEG: in most cases these potential fields describe circular paths within the cortex. Moreover, a multielectrode was developed to explore the different layers of the cortex simultaneously. Both approaches brought enough material to put forward a hypothesis on the origin and the maintenance of so-called synchronized activities.

Animals↗