Roles of Premotor Cortex in Proactive Postural Control Associated with A Rapid Stepping Task in Patients with Stroke
Date Issued
2008
Date
2008
Author(s)
Chang, Wen-Hsing
Abstract
Objective: To investigate the influence of PMC lesion on human proactive postural control as well as the preparation and selection of lower extremity voluntary movement by comparing the performance on proactive postural control and voluntary movement during a rapid stepping task between patients with stroke and healthy adults. Methods: Six stroke patients with the premotor cortex involved (PMC+), seven patients with PMC spared (PMC-), and eight age- and sex-matched healthy adults participated in this study. The subjects were required to respond as quickly as possible with a rapid forward step when the go signal appeared on the screen under two conditions with different predictability level (simple reaction time (SRT) and choice reaction time (CRT)). The accuracy rate of the behavioral responses and reaction time (RT) were assessed to indicate the selection ability. The distribution of combined behavioral-EMG response patterns, the tibialis anterior muscle onset latency (TAOL) and postural-movement latency (TA-Movement latency, TA-Mov) of the stepping leg were analyzed to indicate preparation ability. Results and Discussion: No significant group main effect was found for the accuracy rate of the behavioral responses, but the RT of the PMC+ group was marginally longer than the healthy group (p = .059, effect size = .94). This result may indicate that the PMC+ group required longer time for selecting the appropriate stepping response. For movement-related postural preparation, the PMC+ and PMC- groups displayed significantly more TA delayed trials than the healthy adult group in the CRT condition (p = .007). The TAOL of the stance leg of the PMC+ group was significantly longer than that of the healthy controls while stepping with the unaffected leg (p = .040) and affected leg (p = .024). The TA-Mov showed no significant difference between groups regardless of the stepping legs. These results may suggest that the PMC lesion not only influenced the postural preparation of the affected stepping leg, but also that of the unaffected stance leg through a subcortical pathway. A hypothetical model is proposed to describe the involvement of the PMC in postural preparation and movement selection. Conclusions: This study provided evidence that lesion of the PMC affects the postural preparedness and selection of lower extremity voluntary movement. These findings can be used by clinicians to design effective interventions for improving postural preparedness and selection of voluntary movement for PMC involved patients.
Subjects
Stroke
Premotor cortex
Proactive postural control
Reaction time
Selection
Stepping
SDGs
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