Phase-dependent reflex reversal in human leg muscles during walking

Abstract

1. Reflex responses during walking were elicited in humans by stimulation of the tibial nerve at the ankle. The stimulus intensity was controlled by monitoring the M-wave from an intrinsic foot muscle. Responses were observed in the ipsilateral tibialis anterior (TA), soleus (SO), and rectus femoris (RF) muscles. The most reproducible responses were observed at a middle latency between 50 and 90 ms. The responses were most likely of cutaneous origin, because they closely resembled the responses to stimulation of a purely cutaneous nerve, the sural nerve. 2. A reversal in the direction of the middle latency response from excitation to inhibition was observed for the first time within single muscles during walking. Evidence for a reversal was seen in all three muscles examined and in all seven subjects. 3. The reflex reversal could not be elicited in standing. An inhibition whose amplitude varied in a linear fashion with stimulus intensity and background activation level was always observed at middle latency. The responses elicited during standing resembled those during the stance phase of walking. The two tasks shared some common movement goals and appeared to make use of similar reflex pathways.

A novel approach to mechanical foot stimulation during human locomotion under body weight support

“…Nevertheless, the pilot results are not trivial and may be of interest since they shed some light on the effect of foot pressure and central processing. For instance, from various cutaneous reflexes (Aniss et al, 1992;van Wezel et al, 1997;Yang & Stein, 1990;Zehr & Stein, 1999) one might expect to see a direct effect of foot pressure on motor patterns. In addition, it is well known that loss of cutaneous sensation from the foot can compromise stability in locomotion (Courtemanche et al, 1996;Dingwell & Cavanagh, 2001;Perry et al, 2000).…”

“…In addition, the organization of the interneuronal network for locomotion and the use of corrective reactions during walking points toward a rule-based finite control system rather than a simple additive principle of multisensory fusion (Misiaszek, 2006;Prochazka, 1996). A number of cutaneous reflexes may also participate in the fine control of foot positioning in animals (Guertin, Angel, Perreault, & McCrea, 1995;Schouenborg & Weng, 1994) and humans (Abbruzzese, Rubino, & Schieppati, 1996;Aniss, Gandevia, & Burke, 1992;Sayenko et al, 2007;van Wezel, Ottenhoff, & Duysens, 1997;Yang & Stein, 1990;Zehr & Stein, 1999). Nevertheless, the functional role of specific groups of sensory receptors in regulating human locomotion is still uncertain because they cannot be easily separated since they interact with each other and with central rhythm-generating centers in a complex manner.…”

Mechanically induced stumbling during human treadmill walking

“…Studies on reactions to selective electrical nerve stimu lation during human walking have given insight into the way the central nervous system generates reflex responses to either cutaneous (Duysens et al, 1990(Duysens et al, , 1992Yang and Stein, 1990) or proprioceptive stimulation (Capaday and Stein, 1986;Brooke et al, 1991). Little is known about the role of these reflex responses in compensatory reactions to more realistic perturbations (e.g., stumbling over unex pected objects).…”

Parallel facilitatory reflex pathways from the foot and hip to flexors and extensors in the injured human spinal cord

“…The facilitatory effects of the plantar cutaneous afferents on the TA flexion reflex during hip extension is inconsistent with the general increase in the response during swing and suppression during the transition phase from swing to stance observed in spinal-intact subjects (Yang and Stein, 1990). Similarly, a phase-dependent modulation and reversal of cutaneous reflexes is observed in spinal cats during fictive locomotion (Duysens et al, 1990;Schmidt et al, 1989;Moschovakis et al, 1991;Degtyarenko et al, 1996).…”