Monopodal fictive locomotion evoked by cervical cord stimulation in decerebrate cats

Rhythmic motor discharges evoked by stimulation of the cervical lateral funiculus (LF) were compared with fictive forelimb locomotion evoked by stimulation of the mesencephalic locomotor region (MLR). In the same animals, extensor and flexor nerve discharges alternated in an essentially similar fashion on the LF-stimulated side, but on the contralateral side, such alternated activities were found only in the MLR-evoked fictive locomotion. Thus, it was concluded that the LF-evoked rhythm is monopodal fictive locomotion. Detailed analysis of temporal patterns of nerve discharges during monopodal fictive locomotion revealed 4 components of centrally programmed locomotor discharges for the elbow extensors; tonic back-ground discharges; gradually increasing excitation prior to flexor bursts; small excitation following flexor bursts; crossed excitation. These functional meanings are discussed.