NEONATAL MONOCULAR ENUCLEATION-INDUCED CROSS-MODAL EFFECTS OBSERVED IN THE CORTEX OF ADULT-RAT

The cortices of neonatally enucleated rats were explored for somatosen sory responses with special reference to an extension into the occipit al cortex. Monocular enucleation was performed on rats at birth. The a nimals were raised and from the age of three months the activity evoke d by either electric stimulation of the vibrissa pad or bending of the vibrissae was tested in the contralateral cortex by electric recordin g and autoradiography. It was found that early enucleation caused an e xpansion of the somatosensory responses, among others into the visual area. Neurons responsive to visual and somatosensory stimuli were demo nstrated in the anterior part of the primary and secondary visual area s, contralateral to the enucleation. Electrophysiological and autoradi ographic studies unambiguously proved that early enucleation exerted a significant cross-modal effect on the somatosensory responsive area.