Neuronal plasticity in the nigrostriatal system of the rat after unilateral removal of vibrissae.

The vibrissae of rats were shaved from one side of the face daily for 10 days. To see whether or not this treatment had an effect on crossed and uncrossed striatal afferent connections from the midbrain, the tract tracer horseradish peroxidase was applied to the caudate-putamen on day 11. When the tracer was deposited on the side opposite the vibrissae removal, more labeled cells were found in the contralateral substantia nigra than when it was applied on the same side as the vibrissae removal, or placed in animals with intact vibrissae. Unilateral removal of vibrissae did not affect uptake of the tracer by the cells which give rise to the homolateral nigrostriatal projections. These changes in HRP labeling in the crossed projection from the substantia nigra were seen after 10 days of unilateral removal of the vibrissae; i.e., at a time when the animals have had opportunity to learn to compensate for vibrissotomy-induced behavioral asymmetries.