Studies on the Medial Reticular Formation during Locomotion in Chronic Cats Using Microstimulation and Unit Recording

Abstract

The results from previous studies on the role of the medullary reticular formation (MRF) during locomotion suggest that it is Implicated primarily in the control of ipsilateral flexor muscles (Orlovsky 1970, 1972; Shimamura et al. 1982; Shimamura and Kogure 1983). This emphasis on the flexor musculature, however, is rather paradoxical when seen against the known anatomical connections of the MRF with both flexor and extensor muscles of the hindlimb (Peterson et al 1979). Furthermore, in the spontaneously walking thalamic cat, our recently published results have shown that microstimulation of the MRF may strongly excite both flexor and extensor muscles during the period of their activity (Drew and Rossignol 1984). These stimulation experiments have now been extended to intact cats chronically implanted with EMG electrodes, and have been supplemented by single unit recordings of identified reticulospinal neurons from the same preparation.