ROLE OF SENSORY-EVOKED NMDA PLATEAU POTENTIALS IN THE INITIATION OF LOCOMOTION

Reticulospinal (RS) neurons constitute the main descending motor syste m of lampreys. This study reports an natural conditions whereby N-meth yl-D-aspartate (NMDA)-mediated plateau potentials were elicited and as sociated with the onset of locomotion. Reticulospinal neurons responde d in a linear fashion to mild skin stimulation. With stronger stimuli, large depolarizing plateaus with spiking activity were elicited and w ere accompanied by swimming movements, Calcium imaging revealed sustai ned intracellular calcium rise upon sensory stimulation. Blocking NMDA receptors on RS neurons prevented the plateau potentials as well as t he associated rise in intracellular calcium. Thus, the activation of N MDA receptors mediates a switch from sensory-reception mode to a motor command mode in RS neurons.