Brainstem nucleus MdV mediates skilled forelimb motor tasks.

MARIA SOLEDAD ESPOSITO; PAOLO CAPELLI; SILVIA ARBER

Spitsbergen

Conferencia; Neuronal Networks in the Arctic; 2014

Translating the behavioural output of the nervous systeminto movement involves interaction between brain and spinal cord. The brainstemprovides an essential bridge between the two structures, but circuit-level organizationand function of this intermediary system remain poorly understood. Here we useintersectional virus tracing and genetic strategies in mice to reveal aselective synaptic connectivity matrix between brainstem substructures andfunctionally distinct spinal motor neurons that regulate limb movement. Thebrainstem nucleus medullary reticular formation ventral part (MdV) stands outas specifically targeting subpopulations of forelimb-innervating motor neurons.Its glutamatergic premotor neurons receive synaptic input from key upper motorcentres and are recruited during motor tasks. Selective neuronal ablation orsilencing experiments reveal that MdV is critically important specifically forskilled motor behaviour, including accelerating rotarod and single-food-pelletreaching tasks. Our results indicate that distinct premotor brainstem nucleiaccess spinal subcircuits to mediate task-specific aspects of motor programs.