Initial abnormalities of neuronal responses during epileptogenesis in visual cortex

Publisher Website
Google Scholar
Abstract
Recurrent on-off stimulation with projected images of optimal and suboptimal configuration was presented during the iontophoresis of penicillin from 1 barrel of twin micropipettes around a feline, cortical area 17 neuron whose visual receptive field was previously defined. A progressive enhancement of a neuron''s control or physiologic response (EPR) followed step-wise advances in iontophoresis at low rates (0-60nA). This response alteration was obtained only with stimuli specific for the cell''s receptive field and occurred without evidence of interictal activity. Additional unit spikes with latencies longer than the ERP were elicited at higher rates of iontophoresis (60-200nA) by a variety of non-specific and specific stimuli. These late responses (LR), unlike EPR, were associated with large evoked potentials and were followed by periods of response suppression. The EPR seems to be an alteration in the response properties of individual neurons due to a direct effect of penicillin and as such is an initial and prerequisite abnormality of penicillin epileptogenesis. LR, like the classic paroxysmal depolarization shifts (PDS), appear dependent upon abnormal interactions within a cell population. They may be a secondary elaboration of the EPR of many individual neurons through the aberrant utilization of intra-cortical collateral and recurrent pathways.

This publication has 3 references indexed in Scilit: