One Small Randomly Blinking Dot in an Otherwise Dark Environment: Effects on Visual Cortical Neurons of Kittens

摘要

We raised seven kittens in the presence of a small, randomly blinking, dim light, in an otherwise dark room. We recorded receptive field (RF) properties of single neurons in primary visual cortex, comparing responses of the dot-reared kittens to normally- and dark-reared kittens from the same breeding colony. A substantial number of dot-reared kitten neurons preferred very small moving stimuli, though average RF field size was not significantly smaller than normal kittens'. Only rarely in normal or dark reared kittens did we encounter neurons which preferred very small stimuli. Dot-reared neurons did not prefer ON-OFF stimulation to movement, even though their entire visual experience was with blinking (10 msec duration) not moving stimuli. Compared to dark-reared kittens, there were many fewer non-visual units in the dot-reared sample. Like dark-reared neurons, units in the dot-reared kittens were rarely selective for the direction of movement of stimuli, whereas in our normally-reared sample most units were selective. In the first dot-reared kittens we noted significantly more binocular responses than in our control groups. We challenged the binocular system of t wo more dot-reared kittens by monocular deprivation (MD) in one animal and divergent strabismus in the other. Compared to MD and strabismic kittens reared in our normally lit colony, these two kittens had more binocular neurons, though not as many as the other dot-reared kittens. Because the dot-reared kittens also had good eye alignment compared to dark-reared kittens, we conclude that viewing a solitary blinking dot may exercise a kitten's binocular fixation mechanisms in a way that enhances binocular interaction in visual cortex. (Author)