Reversal of amphetamine-induced circling preference in trained circling rats.

Others have shown that amphetamine given to normal rats causes turning in a particular, preferred direction in most animals. We have studied the effect of training on amphetamine-induced behavioral and biochemical asymmetries in male Sprague-Dawley rats. Water deprived animals were trained to circle either in the same or opposite direction to their intrinsic bias using a sucrose water reward. Acquisition of the learned circling behavior was independent of turning preference and all animals were able to make the operant association. After training, animals given amphetamine turned in the trained direction regardless of their previous circling preference. Amphetamine-induced circling also led to increased dopamine concentrations in caudate contralateral to the trained circling direction. Therefore, intrinsic striatal lateralization is not resistant to behavioral modification and both the behavioral and biochemical asymmetries can be reversed by circling training.