Phasic gating of cutaneous reflexes during locomotion

Abstract

In the course of a movement, mechanical conditions vary, and a reflex response that is effective in one phase of the movement might be ineffective or even disruptive in another phase of the movement. Reflex responses studied in active states, during ongoing movements, have been found to be influenced by the course of the movement. The phasic modulation of skin reflexes during locomotion is perhaps the best studied example. These reflexes have been elicited from the dorsum of the paw and recorded in both the ipsilateral and contralateral hindlimbs (Forssberg et al., 1975, 1977; Prochazka et al, 1978; Forssberg, 1979a,b; Wand et al., 1980; Duysens and Loeb, 1980) or in the forelimbs (Miller et al., 1977). Stimulation of other parts of the limb has also elicited phase-dependent reflexes (Duysens and Pearson, 1976; Duysens and Stein, 1978). The phasic modulation of reflexes has also been found in other motor behaviours such as swimming (Grillner et al., 1977) and respiration (Lipski et al., 1977; Berger and Mitchell, 1976).