TY - JOUR
T1 - Postural preparation prior to stepping in patients with Parkinson's disease
AU - Rogers, Mark W.
AU - Kennedy, Robert
AU - Palmer, Sonia
AU - Pawar, Monika
AU - Reising, Maggie
AU - Martinez, Katherine M.
AU - Simuni, Tanya
AU - Zhang, Yunhui
AU - Mackinnon, Colum D.
PY - 2011/8
Y1 - 2011/8
N2 - People with Parkinson's disease (PD) frequently have difficulties with generating anticipatory postural adjustments (APAs) for forward propulsion and lateral weight transfer when initiating gait. This impairment has been attributed to deficits in motor planning and preparation. This study examined the preparation of APAs prior to an imperative cue to initiate forward stepping. A startling acoustic stimulus (SAS) was used to probe the state of preparation of the APA in eight PD (off medication) and seven matched control subjects. Subjects performed visually cued trials involving a pre-cue light instructing them to prepare to step, followed 3.5 s later by a go-cue light to rapidly initiate stepping. In random trials, a SAS (124 dB) was presented at -1,500, -1,000, -500, -250, -100, or 0 ms before the go-cue. Subjects also performed self-initiated steps. Ground reaction forces (GRFs), center of pressure (CoP) changes, and electromyographic (EMG) signals were recorded. The SAS triggered APAs in 94 ± 11% (PD) and 96 ± 8% (control) of trials at latencies 89 ± 4 ms (PD) and 97 ± 3 ms (control) earlier than Control trials. The temporal profile of APA preparation was similar between groups. However, peak EMG, GRF, and mediolateral CoP amplitudes were reduced in PD. SAS-evoked APAs at 0 ms matched Control trial APAs and were enhanced compared with self-initiated stepping. These results demonstrate that people with mild to moderate PD can plan and prepare the appropriate APA sequence prior to the expected cue to initiate gait; however, the prepared APAs are underscaled in magnitude.
AB - People with Parkinson's disease (PD) frequently have difficulties with generating anticipatory postural adjustments (APAs) for forward propulsion and lateral weight transfer when initiating gait. This impairment has been attributed to deficits in motor planning and preparation. This study examined the preparation of APAs prior to an imperative cue to initiate forward stepping. A startling acoustic stimulus (SAS) was used to probe the state of preparation of the APA in eight PD (off medication) and seven matched control subjects. Subjects performed visually cued trials involving a pre-cue light instructing them to prepare to step, followed 3.5 s later by a go-cue light to rapidly initiate stepping. In random trials, a SAS (124 dB) was presented at -1,500, -1,000, -500, -250, -100, or 0 ms before the go-cue. Subjects also performed self-initiated steps. Ground reaction forces (GRFs), center of pressure (CoP) changes, and electromyographic (EMG) signals were recorded. The SAS triggered APAs in 94 ± 11% (PD) and 96 ± 8% (control) of trials at latencies 89 ± 4 ms (PD) and 97 ± 3 ms (control) earlier than Control trials. The temporal profile of APA preparation was similar between groups. However, peak EMG, GRF, and mediolateral CoP amplitudes were reduced in PD. SAS-evoked APAs at 0 ms matched Control trial APAs and were enhanced compared with self-initiated stepping. These results demonstrate that people with mild to moderate PD can plan and prepare the appropriate APA sequence prior to the expected cue to initiate gait; however, the prepared APAs are underscaled in magnitude.
KW - Akinesia
KW - Gait initiation
KW - Motor preparation
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UR - http://www.scopus.com/inward/citedby.url?scp=80051507353&partnerID=8YFLogxK
U2 - 10.1152/jn.00005.2010
DO - 10.1152/jn.00005.2010
M3 - Article
C2 - 21525376
AN - SCOPUS:80051507353
SN - 0022-3077
VL - 106
SP - 915
EP - 924
JO - Journal of neurophysiology
JF - Journal of neurophysiology
IS - 2
ER -