Investigation of excitatory unit responses arising at different times after application of an electrical stimulus to the cerebral cortex.

Abstract

1. Depending on the distribution of latencies of spike responses to single and repetititve (10 Hz) cortical stimulation at least three groups of excitatory responses can be distinguished from sensomotor neurons: initial (E1), secondary (E2), and postinhibitory (E3). 2. In intercellular recording, depolarization waves, differing in amplitude and duration, and which evidently lie at the basis of the spike responses appearing at different times after application of the stimulus, are detected from the same neuron. 3. Comparison of unit responses to cortical stimuli at different distances from the point of recording, and also of responses recorded in the intact cortex and in an isolated strip of cortex, suggests that type E1 responses are due mainly to the intracortical spread of excitation, whereas responses of types E2 and E3 are due to an excitatory inflow into the cortex from subcortical formations.