Differential effects on locomotor activity of injections of procaine into mediodorsal thalamus and pedunculopontine nucleus.

A comparison was made of the contributions to locomotor activity of output projections of the subpallidal region to the mediodorsal thalamus (MD) and to the pedunculopontine nucleus (PPN). Locomotor activity elicited by injections of picrotoxin into the subpallidal region was reduced by the administration of procaine to the pedunculopontine nucleus but not by the administration of procaine to mediodorsal thalamus. Since the pedunculopontine nucleus is part of the mesencephalic locomotor region (MLR) it appears that subpallido-pedunculopontine projections contribute to the locomotor component of adaptive behaviors associated with limbic integrative activities.