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Abstract:
GOALS: Although previous studies indicate that Alzheimer's
Disease (AD) patients can acquire new motor skills, it is unclear
what processes are involved. Presumably, normal adults depend on
visual-spatial feedback for accuracy when first learning motor
skills, but gradually rely more on kinesthetic information as
practice continues. This study examined the role of vision and
kinesthetic information in motor learning for AD patients. METHOD:
20 AD and 20 elderly control (NC) subjects performed the rotary
pursuit task, tracking a 2cm. target at the edge of a 25cm.
diameter turntable. After determining individual baseline rpm
speeds, subjects received 80 training trials over two days. On the
third day, subjects received 18 trials at baseline speed with 70%
of the target visible, followed by another 18 trials with
restricted vision at a slower speed. RESULTS: Both groups showed
significant improvement in accuracy during training,
F(79,1501)=9.5,p<.01, and both declined under the restricted
vision condition. This decline was significantly larger for ADs, at
baseline, F(1,38)=43.8,p<.001, and slower speeds,
F(1,38)=6.91,p<.05. Unlike the NCs, ADs did not improve with
additional practice under the restricted vision condition.
CONCLUSIONS: Results indicate that, while both groups learned the
task, ADs relied more on vision. A follow-up study replicated this
finding using different subjects. Evidently, AD subjects may
operate in a closed loop mode throughout motor learning, relying
primarily on vision rather than kinesthetics.
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