Further experiments on the influence of afferent stimulation on cortical strychnine discharges

Abstract

Experiments were performed on anesthetized cats provided with cortical convulsive discharges through topical application of 3 per cent strychnine pledgets. Stimulation of the posterior hypothalamus and the ascending reticular formation leads to suppression of strychnine spikes with weak stimuli and to an aggravation of the convulsive discharges with strong stimuli. It is suggested that the suppression is accompanied by asynchrony and the aggravation of the convulsive discharges by asynchrony plus recruitment of previously inactive neurons. The effects are reversible. It was further shown that the effect of hypothalamine or reticular stimulation is determined by the degree of convulsive activity which is present before the stimulation. A cortical site at which the convulsive activity is weak tends to show a suppression in response to a stimulus which intensifies convulsive discharges in an area showing a strong convulsive activity in the control period. Moreover, an area undergoing changes in the degree of convulsive activity with time reacts to a given stimulation in correspondence with this rule. An attempt was made to explain certain deviating findings reported in the literature and to evaluate this work for the clinic of epilepsy.