Dissecting the specificity of hindbrain premotor circuits

MARIA SOLEDAD ESPOSITO; PAOLO CAPELLI; SILVIA ARBER

Basilea

Congreso; Biozentrum Symposium; 2012

Motor behavior is the ultimate output of all brain processing and results from the complex sequence of muscle contraction and relaxation at a precise time. A crucial step of control for this system is played by neurons monosynaptically connected to motor neurons, the so called premotor neurons. We used monosynaptically restricted trans-synaptic rabies viruses to visualize premotor neurons in the hindbrain, connecting to functionally distinct motor neuron pools (Stepien et al. 2010). Comparative analysis of 3D reconstructions revealed differences in premotor distribution from different motor neuron pools. We further demonstrate that the caudal most part of the reticular formation contains glutamatergic neurons directly connecting to a specific subset of forelimb but not hindlimb motor neurons and receiving cortical input. We postulate that these premotor neurons may be part of a modular system controlling co-activation of motor neurons activated during specific tasks such as reaching movements of the forelimbs.