[Electrophysiological indices of the degree of functional integration of a cortical transplant with the brain of the recipient].

Pieces of the embryonal rat neocortex were grafted into the cavity at the place of the barrel-field of adult rats. Neuronal discharges and slow activity were recorded in 11 grafts 3-8 months after the grafting. Neurons of nine grafts responded to vibrissae deflection, their background activity consisted of randomly distributed discharges as in the normal cortex. The similar slow activity was observed in the responding grafts and in the host's intact contralateral barrel-field. Neurons of two grafts did not respond to vibrissae deflection. Hypersynchronous discharges prevailed in their background activity as well as slow delta-waves and epileptiform sharp spikes and waves. Complexes predominated in slow activity of these grafts. Histology revealed a close contact between responding grafts and host brain tissue. Nonresponding grafts were separated from the host brain by a thick glial scar which apparently prevented the axonal exchange between them.