Binocularly deprived cats: binocular tests
Izumi Ohzawa, and Ralph D. Freeman (1988b)
Binocularly deprived cats: binocular tests of cortical cells show regular patterns of interaction.
J. Neurosci. 8: 2507-2516.
If an animal is prevented from receiving visual experience during an
early developmental phase, pronounced dysfunctions are observed.
Physiological tests reveal gross abnormalities in the striate cortex. Cells
in visual cortex are either unresponsive of their response characteristics
are erratic. Although fewer than normal numbers of binocular cells are
found in cats reared with binocular lid suture, a population remains that
can be activated by stimulation through either eye. We have studied
cortical cells in binocularly deprived cats in order to specify monocular
and binocular response characteristics. The primary hypothesis we have
examined is that the abnormal response properties of these cells are a
result of an irregular structure or substructure of the receptive fields.
Kittens were binocularly lid-sutured soon after birth, and were studied
physiologically at ages between 7 and 11 months. Standard techniques were
used to record from single cells in striate cortex. Drifting gratings were
presented to either eye or to both eyes together. In the latter case, the
relative interocular phase was varied between the gratings so that the
retinal disparity of the stimuli was changed. We confirmed the expected
finding that most cells were either unresponsive or erratic in their
response. Of the cells that responded, monocular tuning functions for
orientation and spatial frequency of the stimulus were often irregular.
However, even in these cases, binocular interaction patterns of cortical
responses were nearly always highly regular and displayed phase-specific
profiles. A model is presented that explains this finding and suggests how
binocular deprivation may result in disorganized receptive-field structure.