Thalamic projections to the subthalamic nucleus contribute to movement initiation and rescue of parkinsonian symptoms.

The parafascicular nucleus (Pf) of the thalamus provides major projections to the basal ganglia, a set of subcortical nuclei involved in action initiation. Here, we show that Pf projections to the subthalamic nucleus (STN), but not to the striatum, are responsible for movement initiation. Because the STN is a major target of deep brain stimulation treatments for Parkinson's disease, we tested the effect of selective stimulation of Pf-STN projections in a mouse model of PD. Bilateral dopamine depletion with 6-OHDA created complete akinesia in mice, but Pf-STN stimulation immediately and markedly restored a variety of natural behaviors. Our results therefore revealed a functionally novel neural pathway for the initiation of movements that can be recruited to rescue movement deficits after dopamine depletion. They not only shed light on the clinical efficacy of conventional STN DBS but also suggest more selective and improved stimulation strategies for the treatment of parkinsonian symptoms.