Effect of Time and Direction Preparation on Ankle Muscle Response During Backward Translation of a Support Surface in Stance

Abstract

This study investigated the effect of the time and direction preparation on the electromyographic (EMG) response of the ankle extensor to the backward translation of the support surface in stance. Fifteen healthy adult males aged 35.9 ± 6.2 years participated in this study. In the constant session, the interval between the warning cue and the onset of the backward support surface translation was constant. In the random time session, the interval was randomly assigned in each trial, but the direction was backward across the trials. In the random direction session, the direction was randomly assigned in each trial, but the interval was constant. The EMG amplitude in the time epochs 100–175 ms after translation onset in the random time session was significantly greater than that in the constant session in the soleus, gastrocnemius, and tibialis anterior muscles. The EMG amplitude in the time epochs 120–185 ms after translation onset in the random direction session was significantly greater than that in the constant session in the gastrocnemius and tibialis anterior muscles. This finding indicates that time and direction preparation reduces the late component of the ankle EMG response to backward translation of the support surface. This finding is explained by the supposed process through which uncertainty of the upcoming event causes disinhibition of response or by how time and direction preparation optimizes the magnitude of the long-latency response mediated by the transcortical pathway.

Sympathetic Response to Postural Perturbation in Stance

“…The corticospinal excitability in the tibialis anterior muscle before the perturbation in stance is greater when the onset of the perturbation is predictable (Fujio et al, 2018). Direction prediction reduces the long-latency muscle response to perturbation (Matsuoka et al, 2020). Those findings indicate that time or direction preparation changes the motor response to the perturbation in stance.…”

“…The displacement of the center of pressure induced by the perturbation in stance is smaller when the onset of the perturbation is predictable (Jacobs and Horak, 2007;Jacobs et al, 2008). Time prediction reduces the late response of the ankle muscles to the perturbation in stance (Fujio et al, 2016;Matsuoka et al, 2020). The corticospinal excitability in the tibialis anterior muscle before the perturbation in stance is greater when the onset of the perturbation is predictable (Fujio et al, 2018).…”

Responses of stance leg muscles induced by support surface translation during gait

“…The response of the leg muscles to the support surface translation is prepared by central set ( Horak and Nashner, 1986 ; Horak et al., 1989 ). The prediction of time point and direction of the support surface translation reduced the late component of the ankle EMG response to the backward translation of the support surface ( Matsuoka et al., 2020 ). Cognitive load (silent backward counting in steps of seven) reduced the body sway induced by the vibration over the gastrocnemius muscles causing twitch of those muscles ( Andersson et al., 2002 ), and reduced the late components of the ankle muscle responses to the perturbation in stance ( Rankin et al., 2000 ).…”

Advanced cueing of auditory stimulus to the head induces body sway in the direction opposite to the stimulus site during quiet stance in male participants

“…The participants could have predicted the forthcoming TMS when the coil was placed over the back of the head. Predicting the perturbation changed the motor response to the perturbation (Caudron et al, 2008 ; Jacobs et al, 2008 ; Matsuoka et al, 2020 ) and influenced the vestibular function when the participants were in the stance (Guerraz and Day, 2005 ). Previous findings are consistent with the hypothesis that postural control in a quiet stance is influenced by predicting the forthcoming stimulus.…”