[Maturation of thalamic inputs into the association area of the neocortex during postnatal ontogeny in the cat]

Thalamic afferents into the sensorimotor and parietal cortex (area 7) were studied using the method of retrograde axonal transport of horseradish peroxidase (HRP) in kittens of three age groups. Following HRP injection into the sensorimotor cortex of 2 and 3-day kittens labeled cells were found in the VPL, VPM, MD, CM and CL nuclei. In 21-30-day kittens labeled cells were also revealed in VL. Following HRP injection into area 7 of 1-, 2- and 3-day kittens labeled cells were found in LP, VA and Pulv. Both in 9-, 10-day and 21-30-day kittens, labeled cells were also found in LD and CL. The results suggest that differences in the thalamic connections of single cortical areas can be distinguished during the postnatal ontogenesis of the brain.