Observations on strychninised isolated cortex

Abstract

1. 1. Electrical stimulation of isolated and strychninised cortex was carried out in cats. 2. 2. No spontaneous activity or strychnine spikes occur in isolated cortex. 3. 3. Electrical stimulation of isolated and strychninised cortex elicits typical strychnine spikes. The threshold at which spikes are elicited increases with the distance between the strychninised zone and the point of stimulation. 4. 4. The maximum frequency at which strychnine spikes occur is 3.5/sec. irrespective of the frequency of repetitive stimulation. A series of spikes at 2 or 3.5/sec. can only be maintained for approximately 30 sec. 5. 5. Electrical stimulation of intact, spontaneously active cortex elicits spikes in an inconstant manner and a series of spikes cannot be maintained with repetitive stimulation. 6. 6. The mechanism determining the length of a train of evoked spikes is discussed on the basis of interference between the activity produced by the stimulation and that produced by the strychnine spike itself. 7. 7. The manner in which the mechanisms underlying these observations might elucidate some of the features of petit mal discharges are discussed.