Journal of Neurophysiology, Vol 41, Issue 4 1007-1013, Copyright © 1978 by APS
Postnatal development of visually evoked activity within motor cortex of cat
J. D. Glass, G. H. Fromm, A. S. Chattha and R. D. Bloom
1. The development of visually evoked activity within motor cortex was
studied in chloralose-anesthetized kittens of 3, 4, and 5 mo of age and
adult cats. 2. The slow-wave response from motor cortex of the adult cat is
a triphasic negative-positive-negative wave. In 3-mo-old kittens the
response is only a long-duration negative wave, while at 4 mo the positive
and late negative waves emerge, and at 5 mo of age the adult form of the
response is present. 3. Single neurons in the adult respond to the light
during the positive component of the slow-wave response. When only the
negative wave is present in kittens of 3 and 4 mo of age, neurons do not
respond to the photic stimulus. At 5 mo of age the correlation between unit
activity and the positive component of the response is identical to the
adult. 4. The laminar analysis of the positive component of the response
suggests that it originates relatively superficially in cortex and migrates
down toward the deeper layers. Its correlation with unit activity indicates
that the positive component represents excitatory postsynaptic potentials.
5. These results are consistent with an excitatory drive on neurons within
motor cortex undergoing development change until the 5th mo of life.
