VISUAL RESPONSE PROPERTIES AND VISUOTOPIC REPRESENTATION IN THE NEWBORN
MONKEY SUPERIOR COLLICULUS.
M. T. Wallace, J.G. McHaffie and B. E. Stein.
Department of Neurobiology and Anatomy, Bowman Gray School of Medicine/Wake
Forest University, Winston-Salem, NC 27157.
APStracts 4:170N, 1997.
ABSTRACT
Visually-responsive neurons were recorded in the superior colliculus (SC) of
the newborn rhesus monkey. The receptive fields of these neurons were larger
than those in the adult, but were already organized into a well-ordered map of
visual space that was very much like that seen in mature animals. This
included a marked expansion of the representation of the central 10o of the
visual field and a systematic foveal to peripheral increase in receptive field
size.
Although newborn SC neurons had longer response latencies than did their adult
counterparts, they responded vigorously to visual stimuli and exhibited many
visual response properties that are characteristic of the adult. These
included surround inhibition, within-field spatial summation, within-field
spatial inhibition, binocularity and an adult-like ocular dominance
distribution. As in the adult, SC neurons in the newborn preferred a moving
visual stimulus, and had adult-like selectivities for stimulus speed.
The developmentally advanced state of the functional circuitry of the newborn
monkey SC contrasts with the comparative immaturity of neurons in its visual
cortex. It also contrasts with observations on the state of maturation of the
newborn SC in other developmental models (e.g., cat). The observation that
extensive visual experience is not necessary for the development of many
adult-like SC response properties in the monkey SC may help explain the
substantial visual capabilities shown by primates soon after birth.
Received 17 April 1997; accepted in final form 24 July 1997.
APS Manuscript Number J311-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997