Effect of Removing the Neocortex on the Response to Repeated Sensory Stimulation of Neurones in the Mid-brain

Abstract

THE response of a high proportion of cells in the superior colliculus and subjacent structures (tecto-tegmental region) of the rabbit mid-brain gradually wanes when a sensory stimulus is repeatedly presented at rates between 1 per sec and 1/4 per sec^1,2. The number of stimuli required to bring about attenuation of response (habituation) varies from cell to cell and, for a given cell, from stimulus to stimulus, but lies between two and fifty presentations. The response may be restored by withholding the stimulus for some 20 sec or more and presenting it again (recovery by time lapse). In the experiments on which these observations are based, the animals were anaesthetized with urethane-pentobarbitone and the recording micro-electrodes directed to the mid-brain by a hole drilled in the skull. Thus apart from the tracks made by the electrodes the cerebral cortex was intact.