Is the velocity-curvature relationship disrupted in apraxic patients?
Velocity and curvature of human movements are linked by a proportionality relationship (power-law) whose origin has been attributed either to functional properties of cortical areas or to peripheral constraints. 3D movements made by apraxic patients show a time-shift between velocity and curvature which has been considered as a disruption of the power-law, supporting the central hypothesis. We analysed the power-law in 2D drawing-like movements in healthy subjects and apraxic patients (correlation and cross-correlation analyses). The power-law remained preserved in apraxic patients, suggesting that the velocity-curvature relationship is not globally disrupted and thus that the power-law cannot be only attributed to central planning mechanisms in those associative brain areas injured in apraxic patients.
Jacobs
S
S
CNRS UMR 8119. 45, rue des Saints Pères, 75006 Paris, France. stephane.jacobs@biomdicale.univ-paris5.fr
Hanneton
S
S
Heude
S
S
Roby-Brami
A
A
D000328:Adult; D000368:Aged; D001072:Apraxias / Q000523:psychology*; D001696:Biomechanical Phenomena; D005260:Female; D005556:Form Perception / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009039:Motion Perception / Q000502:physiology*