Role of the premotor cortex in leg selection and anticipatory postural adjustments associated with a rapid stepping task in patients with stroke

Chang, Wen-Hsing; Tang, Pei-Fang; Wang, Yao-Hung; Lin, Kwan-Hwa; Chiu, Ming-Jang; Chen, Shen-Hsing Annabel

doi:10.1016/j.gaitpost.2010.07.007

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Volume 32, Issue 4 , Pages 487-493, October 2010

Role of the premotor cortex in leg selection and anticipatory postural adjustments associated with a rapid stepping task in patients with stroke

Wen-Hsing Chang
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC
- Department of Physical Therapy, Taipei Medical University-Shuan Ho Hospital, Taipei, Taiwan, ROC
Pei-Fang Tang
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC
- Physical Therapy Center, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, ROC
- Corresponding author at: School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Floor 3, No. 17, Xuzhou Rd., Zhongzheng District, Taipei City 100, Taiwan, ROC. Tel.: +886 2 3366 8128; fax: +886 2 3366 8161.
Yao-Hung Wang
- Department of Medical Imaging, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, ROC
Kwan-Hwa Lin
- School and Graduate Institute of Physical Therapy, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC
- Physical Therapy Center, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, ROC
Ming-Jang Chiu
- Department of Neurology, National Taiwan University Hospital and National Taiwan University College of Medicine, Taipei, Taiwan, ROC
Shen-Hsing Annabel Chen
- Department of Psychology, College of Science, National Taiwan University, Taipei, Taiwan, ROC
- Division of Psychology, Nanyang Technological University, Singapore

Received 13 January 2009; received in revised form 23 June 2010; accepted 12 July 2010. published online 11 August 2010.

Abstract

The premotor cortex (PMC) plays an important role in selecting and preparing for movement. This study investigates how stroke-induced PMC lesions affect stepping leg selection and anticipatory postural adjustments (APAs) preparation. Fifteen hemi-paretic patients (eight with PMC lesions (PMC_Lesion) and seven PMC spared (PMC_Spared)) and eight age- and sex-matched healthy adults participated in the study. The subjects performed rapid forward stepping with the right or left leg under simple and choice reaction time conditions. The percentage of trials in which the subject showed the correct initial vertical ground reaction force pattern before lift-off of the stepping leg indicated the accuracy in selecting the designated stepping leg. The latency of bilateral contractions in the tibialis anterior (TA) and the reaction time (RT) of the stepping leg represented the time needed to prepare for stepping-related APAs and stepping movement, respectively. All three groups demonstrated a similar rate of accuracy of the stepping leg selection under both conditions. However, in both conditions, the PMC_Lesion group exhibited a longer RT and TA contraction latency of the affected leg than the healthy and PMC_Spared groups. The PMC_Lesion group also presented a longer TA contraction latency of the unaffected leg than the healthy group in both conditions. These results suggest that the PMC is involved in APAs associated with leg stepping movement and that a PMC lesion in one hemisphere impairs APAs of both the contralateral and ipsilateral legs during stepping.

Keywords: Stroke, Premotor cortex, Anticipatory postural adjustments, Preparation, Selection