Binocular cross-orientation suppression in the primary visual cortex (V1) of infant rhesus monkeys.
OBJECTIVE
To better understand the course of cortical maturation during early development, the phenomenon of binocular cross-orientation suppression in neurons of the primary visual cortex (V1) in young infant monkeys was investigated.


METHODS
Extracellular single-unit recordings were made in anesthetized and paralyzed monkeys ranging in age between 6 days and 8 weeks. Orthogonally oriented, dichoptic sine-wave gratings were used as visual stimuli.


RESULTS
V1 neurons in young infant monkeys showed a higher prevalence and greater magnitude of binocular cross-orientation suppression than in adult monkeys. Binocular suppression decreased and reached an adult level between 4 and 8 weeks of age, the presumed onset-age for stereopsis in monkeys.


CONCLUSIONS
During the first 4 weeks of life, the functional connections that are necessary for initiating binocular cross-orientation suppression exist in the monkey primary visual cortex. This finding is consistent with the view that before the abrupt onset of stereopsis, human infants may detect the differences between interocularly iso-oriented gratings and orthogonal gratings.
Endo
M
M
College of Optometry, University of Houston, Houston, Texas, USA.
Kaas
J H
JH
Jain
N
N
Smith
E L
EL
Chino
Y
Y
D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D003867:Depth Perception / Q000502:physiology; D008253:Macaca mulatta / Q000502:physiology*; D009474:Neurons / Q000502:physiology; D009949:Orientation / Q000502:physiology*; D015348:Vision, Binocular / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*