Cervical interneurones oligosynaptically excited from primary afferents and rhythmically active during forelimb fictive locomotion in the cat

In C6-C7, activity of neurones oligosynaptically excited from primary afferents was examined during fictive locomotion. Two kinds of neurones were found: neurones with activity modulated and with activity not modulated. The minimum linkage of the pathway to modulated neurones was mono- and disynaptic from muscle and cutaneous afferents, respectively, while non-modulated neurones were monosynaptically excited from both afferents. Modulated neurones were mainly located in the ventral part of the dorsal horn and adjoining intermediate region, non-modulated ones located in the dorsal horn. Modulated neurones were found near motor nuclei as well. Active periods of modulated neurones were widely distributed in the step cycle.