Extracellular recordings were made from the dorsal lateral geniculate nucleus of monocularly deprived, dark-reared and normal cats. The spatial and temporal properties of the neurones were studied. 2. The mean acuity of X-cells with receptive fields 3 degrees of the area centralis was 3.9 c/degree for deprived eye cells from monocularly deprived cats, compared was 3.8 c/degree for normal cells. 3. The mean activity of X-cells with receptive fields within 4 degrees of the area centralis was 4.3 c/degree for a dark-reared cat compared with 4.0 c/degree for a normal cat. 4. The peak response rates of X-cells to their best spatial frequency were determined. The mean values for the normal, monocularly deprived and dark-reared populations were all similar. 5 Measurement of the temporal frequency tuning of a number of cells was made. The mean peak temporal frequency for the dark-reared X-cells was lower than for monocularly deprived or normal X-cells. 6. The results are discussed with reference to the location of the primary neural deficit induced by visual deprivation.
