[The effect of the limitation of afferent inflow in early ontogeny on the evoked activity of projective neurons depends on the degree of the maturity of the sensory inputs].

The study is focused on the influence of a partial limitation of the sensory inflow in rat pups on the development of the sensory systems, which mature earlier and later. In accordance with the ontogenetic rule of proximal-distal maturation, the sensory inflow from the forelimbs matures faster than that from the hindlimbs. Fourteen Wistar rat pups (from 28) were deafferented on the 13th day of postnatal ontogeny (a small portion of the median nerve was unilaterally dissected). The background and evoked activity of single neurons was recorded in 26-47-day-old pups in the somatosensory cortex (in the projection areas of the intact n. medianus, which matures earlier, and n. ischiadicus, which matures later). The changes in firing activity produced by deafferentation were observed. In the projection area of the intact forelimb of the denervated rats, the incidence of inhibitory responses significantly increased, whereas the incidence of completes responses significantly decreased. In the hindlimb projection area of the denervated animals the background firing rate was significantly lower and the incidence of activation responses was increased.