Experience-dependent maturation of the spatial and temporal characteristics of the cell receptive fields in the kitten visual cortex.

The development of contrast sensitivity to spatial and temporal frequencies was studied in the visual cortex of 6-week-old kittens reared from birth in three conditions: normal, dark-reared (DR) and dark-reared after 6 h of visual experience. Receptive fields of cells recorded in area 17 were quantitatively analysed using drifting sine-wave gratings. Compared to the low values obtained in the DR kittens, we observed after 6 h of visual experience: (1) an adult-like detection of higher spatial frequencies, (2) an increase of contrast sensitivity at low temporal frequencies; (3) a shift of the cell optimum towards 3 Hz, all values close to the normal ones.

Long-term effects of dark rearing on a visually guided reaching movement in cats.

The existence of long-term effects of dark-rearing on visuo-motor coordination is still controversial. In this study 2 dark-reared (DR) cats were trained, after 5-6 years of recovery, to perform a reaching movement towards a stationary or a moving target. The accuracy, and the reaction and movement times were evaluated.

Temporal correlations in modulated evoked responses in the visual cortical cells of the cat.

We analysed evoked responses recorded from 97 cells in the visual cortex of 4 adult cats and 8 kittens, stimulated by a drifting sinusoidal grating. A Fourier analysis of the responses allowed us to select 30 cells showing a clear modulating response (relative modulation index greater than 1). The 162 records from these selected cells were scanned to detect precise temporal correlations in the form of replicating triplets and associated "ghost" doublets.