Subcortical regulation of cortical development: some effects of early, selective deprivations.

Selective deprivations, such as the lack of sensory input, of social contacts and of language during the critical (sensitive) period of brain development have profound consequences for the structure and function of the adult brain. The field is largely uncharted since only the consequences of the most severe forms of deprivation are known, and that too only in a few systems. It is similarly unknown if the opposite of deprivation, selective over-stimulation in development, which appears to enhance the acquisition of certain skills, for example musical skills, has collateral deprivation-like effects in other domains. In spite of these uncertainties, I propose that the common mechanism underlying the effects of deprivation may be the altered stabilization of neuronal morphologies, particularly connectivity, in the period when their exuberant development is down regulated.