Electrographic manifestation of drowsiness in the isolated cat cortex.

Electrical activity of the neuronally isolated cortex during waking and the onset of sleep was investigated in experiments on freely behaving cats. The transition from wakefulness to sleep is accompanied in the isolated cortex by the appearance of a stage of drowsiness, accompanied by corresponding changes in the electrocorticogram of the isolated hemisphere. The electrographic manifestation of the stage of drowsiness in the isolated cortex depends on the time elapsing after the operation and it is most marked in the late period after isolation of the cortex.