Convulsive potentials have been elicited from the cortex of cats by employing strychnine and d-tubocurarine and also by employing one of these drugs together with eserinized acetylcholine solution. A study has been made of the neuronal substrates of these seizure potentials with surface and deep recordings and with micro-electrodes. Strychnine and d-tubocurarine potentials may arise in a narcotized cortex and in this case they are not accompanied by unit activity. The latter occurs only in waking animals and mostly during the first positive phase of these potentials. Under the influence of eserinized acetylcholine the elicitability of these potentials is greatly enhanced, and their refractory period is shortened remarkably. In the later phase of this combined action rhythmic after-discharges appear in the cortex. These are not confined to the upper 500-600 μ of the cortex like the strychnine and d-tubocurarine spikes, but are detected in its entire depth. Unit discharges can be observed on such ocassions in exact correlation with each surface wave. Rhythmic after-discharges do not occur without unit activity. The authors conclude that the neuronal substrate of the rhythmic after-discharge, which remarkably resembles the epileptic electrogram, is an intracortical reverberating circuit in which the excitation proceeds from the surface towards the depth, where it is transmitted and led back to the surface. This reverberating circuit, which sends impulses towards other cerebral regions and also towards the periphery, can be interrupted by applying atropine. The above type of discharge is considered by the authors to be the model of the epileptic seizure discharge.
|Number of pages||8|
|Journal||Electroencephalography and Clinical Neurophysiology|
|Publication status||Published - Dec 1965|
ASJC Scopus subject areas
- Clinical Neurology