Modification of the kitten's visual cortex by exposure to spatially periodic patterns.

Kittens were dark-reared except for exposure to three types of spatially periodic, vertically striped pattern: 1. single, widely spaced black bars; 2. wide areas of regular vertical grating separated by large blank patches; 3. a uniform, continuous grating with a spatial frequency of 0.5 c/deg. In each case there was a bias towards vertical in the distribution of preferred orientations of cells recorded in the visual cortex. The contrast sensitivity of individual neurones for gratings of different spatial frequencies was analysed quantitatively. In kittens exposed to a uniform grating of 0.5 c/deg, many cells were maximally sensitive close to 0.5 c/deg, as they are in normal cats. The occipital potential evoked by vertical gratings higher in frequency than 0.3 c/deg was consistently greater in amplitude than that for horizontal, and a vertical grating of 0.5 c/deg produced the maximum activity. These results are compared with those of Maffei and Fiorentini (1974); the differences between our results and theirs may be attributable to the degree of variability in spatial frequency and orientation during rearing, and to the duration of exposure.