Unraveling the projection-stratified anatomical and molecular organization of the Deep Cerebellar Nuclei

Movement is the main output of the central and peripheral nervous systems. Our daily lives depend on the precise coordination and execution of movements involving multiple limbs. The neuronal circuits which mediate and coordinate movement span throughout the brain and involve the integration of information across the brain’s motor centers to modulate execution, learning, and action planning. Recently, groundbreaking work in the brainstem, cerebellum, and motor cortex have provided a framework for developing methods, designing experiments, and conjuring hypotheses to understand how movement is controlled. Research dedicated to delineating spatially intermingled neuronal populations in the mouse brainstem, gave rise to the work that will be described in this thesis. Specifically, we describe how neurons in the deep cerebellar nuclei (DCN), the sole output of the cerebellum and a structure canonically known as devoted to online motor control, are connected to the brainstem and thalamus. We find a high degree of synaptic specificity with respect to target regions innervated by different subpopulations of DCN neurons. Using a myriad of genetic, viral, and molecular tools, we identify previously uncharacterized anatomical and molecular cell types in the deep cerebellar nuclei and brainstem.