[Mechanism of the generation of evoked potentials in the rabbit neocortex]

This paper describes the analyses of evoked potentials recorded in different neocortical areas (Area precentralis 1 and 2, occipitalis 1 and 2) and elicited by different stimulation techniques (antidromic stimulation of the pyramidal tract, electrical stimulation of thalamic nuclei, the optic nerve and finally random dot stimulation of the retina). Field potentials were recorded intracortically with a 16-fold electrode. The analyses of field potentials with the current-source-density method yielded an estimation of the current source and sink density distributions within the six neocortical layers. Hence spatio-temporal patterns of layer specific activation processes (sinks and sources) can be described for the various evoked potentials. The results can be summarized as follows: every evoked potential shows a spatio-temporal pattern of sources and sinks which is independent of the neocortical area and the mode of stimulation. However, the late components of the evoked potentials show great variations in their generation mechanisms, thus indicating regional differences in neocortical architectonics. These observations are discussed with regard to morphology, electrical activity and functional properties of the studied neocortical areas.