Early visual deprivation alters modality of neuronal responses in area 19 of monkey cortex.

Monkeys deprived on vision during the first year of life by lid suture appear functionally blind after the opening of the eyes, but move actively in familiar surroundings using somesthetic cues. Microelectrode recordings of multiple unit activity in the associative visual cortical area 19 of deprived monkeys indicated that 20% of the neuron groups studies responded only during active somatic exploration. In normal animals all neuron groups studied responses exclusively to visual stimuli, but in the deprived animals only 40% of them did. Visual deprivation alters the synaptic pathways to visual associative cortex enhancing the efficiency of those inputs that can mediate somatic information to this region.