DEVELOPMENT OF EVOKED RESPONSES IN VISUAL AND AUDITORY CORTICES OF KITTENS

Abstract

Responses have been evoked in the auditory and visual cortices of kittens from 1 to 6 weeks of age and in adolescent and adult cats by natural stimuli. At first appearance visual evoked responses tend to be monophasic negative or double negative in wave-form, auditory responses biphasic positive-negative. Amplitude of responses is lower, and latencies are 8-10 times longer than in adults. Responsiveness to repetitive stimulation is poor. Individual differences are great in the very young cat and diminish with age. Auditory responses attain adult form and latency by 4-5 weeks of age; visual responses have still not done so at 6 weeks of age. The visual system appears to develop later than the auditory by several criteria. A maturational correlation between the visual and auditory systems could not be demonstrated by a comparison of response latency measurements.