Article

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.
CI - Copyright (c) 2010 Elsevier B.V. All rights reserved.

Langue : ANGLAIS