[Correlates of potentials evoked by motivational processes in aversive conditioning].
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Animals↗
Biomedical subjects
V Csépe
Publications and source records attributed to V Csépe.
A new multielectrode for chronic recording of intracortical field potentials in cats.
The analysis of intracortical field potentials in freely moving animals may help to reveal the origin of evoked potential components displaying characteristic changes in behavioral experiments. The authors describe a chronically implantable multielectrode made of 7 teflon insulated platinum wires of 75 microns diameter. The novelty of this multielectrode is that the wires are not glued together but penetrate into the cortex independently. In the final position the cut ends serving as recording surfaces are situated in the cortical tissue below each other at equal distances of 300-400 microns. This arrangement made possible the artifact free recording of the evoked field potentials from the different depths of the auditory cortex for months. Phase reversal, known from the classical studies, could be observed only in the first surface positive component, while the late waves appeared homogeneously throughout the whole depth of the cortex.
Animals↗
Evoked magnetic responses of the human auditory cortex to minor pitch changes: localization of the mismatch field.
The neuromagnetic source localizations of the auditory M100 and the mismatch field (MMF) were studied using a large-array biomagnetometer. Standard tones of 1000 Hz and deviant tones of 1050 Hz were delivered with 90% and 10% probability, respectively. Wave forms of the derived MMF were computed by examining difference wave forms between the responses to the deviants and the responses to the standards preceding (D-P) and following (D-F) the deviants as well as to all remaining standards (D-A). The subset of standards preceding the deviants was used for a more realistic comparison with the set of deviants (having the same number of epochs and a similar signal-to-noise ratio), while the subset of standards following the deviants served to answer the question whether those standards also elicit an MMF. The MMF deflections were compared with each other, with the "native" MMF occurring in response to the deviants, and with wave M100. (The MMF as it appears in the unprocessed response to the deviants was termed "native" for an easy distinction from the "derived" MMF.) Our results demonstrate a distinct MMF deflection, corresponding in latency to the simultaneously recorded fronto-central electrical MMN. Source analysis, using a single moving dipole model, showed the same spatial localization for the native MMF and for the different derived MMFs. The MMF source location turned out to be significantly anterior, medial and inferior relative to the sources of the M100. The present data also demonstrate that a minor frequency deviation may not activate measurably different M100 generators, yet be sufficient to trigger the nearby but spatially distinct mismatch generator.
Acoustic Stimulation↗
Towards the possible clinical application of the mismatch negativity component of event-related potentials.
The mismatch negativity (MMN) is an event-related potential component that signifies neurophysiological processing of fine acoustic differences. The MMN indicates attention-independent change detection, reflects auditory sensory memory and provides a physiological measure of difference sensitivity. This paper will provide an overview of current research where results gained by MMN testing in different patient groups were central to the interpretation of an assumed abnormality of processing or storing acoustic features.
Adult↗