Brainstem nucleus MdV orchestrates skilled limb motor tasks

MARIA SOLEDAD ESPOSITO; PAOLO CAPELLI; SILVIA ARBER

San Diego

Congreso; Society for Neuroscience; 2013

Society for Neuroscience

Movement is the behavioral output of the nervous system and the result of circuit level interactions between brain and spinal cord. Organization and function of descending neuronal circuits bridging these two key structures remain poorly understood. Here we reveal a highly selective synaptic connectivity matrix between brainstem and spinal motor neurons regulating forelimb and hindlimb movement in mice. The caudal brainstem nucleus MdV stood out as strikingly specific in targeting forelimb innervating motor neurons. We find that premotor MdV neurons are glutamatergic, receive synaptic input from several key upper motor centers and are active during motor tasks. Selective neuronal perturbation experiments demonstrate the importance of MdV in the performance of skilled motor tasks. Our findings on the organization of descending pathways to spinal motor neurons suggest that differential use of brainstem nuclei may be at the core of driving programs for motor action diversification.