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Abstract:
Abstract: Apraxia is a disorder of skilled movements which
spares basic sensorimotor functions. In this study we measured hand
movements of 6 apraxic patients with left parietal lobe lesions and
3 normal subjects during reaching for familiar objects under 3
different instructions (grasping, pantomiming object use, actual
object use). We recorded angular variations of the different hand
joints (metacarpal-phalangeal, proximal and distal interphalangeal,
abduction between adjacent fingers and thumb rotation) by means of
an instrumented glove (with 22 motion sensors, Cyberglove, Virtual
Technologies). Factorial analysis showed that, in the pantomime and
actual use conditions, normals' hand postures for the different
objects were distributed along two vectors assuming a V shape in
the plane formed by the first two principal components which
accounted for more the 80% of variance. In contrast, apraxics' hand
postures varied along a single principal component, indicating that
the same finger configuration was applied to the different objects.
No difference were found between the two groups for the simple
grasping condition. These results confirm prior finding which
suggested that apraxia from left parietal lobe lesions alters the
production of learned hand postures specifically during tool use
and other complex gestures (Sirigu et al., Cortex, 31, 41-56,
1995).
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