An inhibitory mechanism in the bulbar reticular formation.

ACCORDING to the doctrine that the nervous system is organized as a series of levels, that portion of the brain stem lying immediately above the spinal cord, and described as bulbar, has traditionally been regarded as a level contributing excitatory influences to motor outflows. The basis for this view is the observation, f&t made by Sherrington (ll), that decerebration leaving only the bulbar part of the brain connected with the cord, is followed by a state of over-activity or rigidity of the anti-gravity muscles. It has not been widely recognized that this bulbar part of the brain stem, in addition, contains a mechanism capable of exerting a general inhibitory influence on motor activity. In the experiments to be reported, this inhibitory influence has been demonstrated by observing the effect of bulbar stimulation upon reflexes, upon decerebrate rigidity and upon responses evoked from the motor cortex.2