Raphé-produced excitation of spinal cord motoneurons in the cat.

In all motoneurons examined, both flexor and extensor, raphé (pallidus) stimulation consistently produced an excitatory postsynaptic potential (EPSP). Upon interaction with a group Ia EPSP there was summation resulting in neuronal discharge. The raphé-induced EPSP also facilitated the initial segment-somadendritic coupling and hence the motoneuron excitability. These data support an excitatory role for raphé-spinal fibers on cat hindlimb motoneurons.