MECHANISMS OF SUPRASPINAL ACTIONS UPON SPINAL CORD ACTIVITIES. RETICULAR INHIBITORY MECHANISMS UPON FLEXOR MOTONEURONS

Abstract

The mechanism by which stimulation of the inhibitory reticular formation prevents the monosynaptic activation of [alpha]-flexor motoneurons was studied by intracellular recording in decerebrate cats following interruption of the spindle loop. It was found that this inhibition is postsynaptic in nature. The hyperpolorization induced by reticular stimulation was only reduced by electrophoretic injection of Cl- capable of reversing a "direct" IPSP [inhibitory post-synaptic potential]. To interpret this finding a model is proposed and discussed, in which the inhibitory synapses involved are said to be located in the dendrites far from the soma.