Postnatal ontogenesis of potentials elicited in the cerebral cortex by afferent stimulation.

The activation of immature rat S1 neocortex by electrical stimulation of peripheral nerves and of the thalamus is described. The existence of a surface-positive potential of intracortical origin at an early stage of development is confirmed. It is also shown that both the augmenting and the recruiting phenomena can be obtained by thalamic stimulation at postnatal days 3-4.