Parallel dopaminergic pathways controlling locomotion in the mouse

Over the last decade substantial progress has been made in understanding the role of descending projections that evoke and control ongoing locomotion. Building on this work, we are exploring A11 in the posterior hypothalamus and A13 neurons in the zona incerta that contain dopaminergic neurons that project to the spinal cord and brainstem. Here we show that photostimulation of the A11 and A13 nuclei can evoke locomotor activity in mice. We present evidence that the A11 projects to the Medullary Reticular Formation (MRF), while the A13 projects to both the Mesencephalic Locomotor Region (MLR) and the MRF. In addition, the A11 projects fibers to the thoracolumbar spinal cord but non-dopaminergic neurons project from the A13 region to the spinal cord. These data suggest an expanded view of dopamine’s role in locomotion beyond the well-known nigrostriatal pathway.