Influence of stimulation of movement-inhibiting areas of the pons on the activity of neurons of the medial region of the medulla oblongata.

The reactions of 249 neurons located in the zones of gigantocellular reticular nucleus and the nucleus raphé magnus in response to electrical stimulation of areas of the cuneate nucleus of the midbrain, the medial parabrachial nucleus, and the central raphé nucleus, which inhibit movement, were analyzed in anesthetized white rats. Reactions to stimulation of these areas of the pons were lacking in 40 cells; 25 neurons were excited antidromically; 48 responded with solitary orthodromic action potentials; prolonged inhibition was observed in 72 neurons following the phase of activation; and 64 cells were tonically excited. The functional identification of the two last groups of neurons showed that the inhibition reactions are primarily recorded in cells receiving tactile and mechano- and nociceptive information, while the neurons which tonically discharge upon stimulation apparently participate in the inhibition of the motoneurons of the hind limbs.