Séminaire de Marco Beato, UCL
Vendredi 9 Septembre à 14h30
ATTENTION le séminaire aura lieu dans l’amphithéâtre 1 (bâtiment de médecine)
Séminaire de Marco Beato, Neuro, Physiology & Pharmacology, University College London
Recurrent circuits involving motoneurons in the spinal cord
Motoneurons have long been considered as the final common pathway of the nervous system, transmitting the neural impulses that are transduced into action by muscles. While many studies have focussed on the inputs that motoneurons receive from local circuits within the spinal cord and from other parts of the CNS, relatively few have investigated the targets of local axonal projections from motoneurons themselves. Anatomical and electrophysiological evidence shows that motoneurons collaterals form synaptic contacts with Renshaw cells, but also with other motoneurons and interneurons in the lumbar spinal cord. These loops are referred to as recurrent inhibition and excitation respectively. Using electrophysiological recordings from connected pairs of cells, I have characterized the unitary synaptic strengths of the components in these circuits and observed some unexpected connectivity patterns between motoneurons and Renshaw cells associated with antagonist muscles. These findings indicate that motoneurons cannot be simply viewed as the last relay station delivering the command drive to muscles, but that they perform an active role in the generation and modulation of motor patterns.