Motor Subcircuits Mediating the Control of Movement Extent and Speed

• Published in: Journal of neurophysiology Vol. 90; no. 6; pp. 3958 - 3966
• Main Authors: Turner, Robert S, Desmurget, Michel, Grethe, Jeff, Crutcher, Michael D, Grafton, Scott T
• Format: Journal Article
• Language: English
• Published: United States Am Phys Soc 01.12.2003
• Subjects: Adult; Aged; Biomechanical Phenomena; Brain Mapping; Cerebrovascular Circulation - physiology; Efferent Pathways - diagnostic imaging; Efferent Pathways - physiology; Female; Humans; Image Interpretation, Computer-Assisted; Male; Middle Aged; Movement - physiology; Nerve Net - diagnostic imaging; Nerve Net - physiology; Psychomotor Performance - physiology; Tomography, Emission-Computed
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.00323.2003

1 Department of Neurology, Emory University School of Medicine, Atlanta, Georgia 30322 2 Department of Neurological Surgery, University of California, San Francisco, California 94122 3 Space and Action, Institut National de la Santé et de la Recherche Médicale U534, 69500 Bron, France 4 Center for Cognitive Neuroscience, Dartmouth College. Hanover, New Hampshire 03755 Submitted 2 April 2003; accepted in final form 29 August 2003 The functional correlates of movement extent, speed, and covariates were investigated using PET mapping of regional cerebral blood flow (rCBF) in 13 healthy right-handed adults. A whole-arm smooth pursuit tracking task was used to strictly control potential confounds such as movement duration, error, and feedback control. During each of four scans, images of relative rCBF were obtained while subjects matched the constant velocity movements of a target using a joystick-controlled cursor. Between scans, subjects were completely adapted to one of four joystick-to-cursor gains, thereby allowing constant visual stimulation and eye movements across arm movements that ranged in extent from 6 to 24 cm. Subjects were unaware of the changes in visuomotor gain. Analyses of arm and eye movements indicated that the only significant difference in behavior across the four gain conditions was the extent and velocity of arm movements, which were closely correlated with each other. Parametric statistical methods identified brain areas where rCBF covaried with the mean movement extent of individual subjects during individual scans. Increasing movement extent was associated with parallel increases of rCBF in bilateral basal ganglia (BG; putamen and globus pallidus) and ipsilateral cerebellum. Modest extent effects were detected also in the sensorimotor cortices bilaterally. No significant inverse relations were found. We conclude that a small subcircuit within the motor control system contributes to the control of movement extent and covariates and that the BG and cerebellum play central roles in the operation of that circuit. Address for reprint requests and other correspondence: R. S. Turner, Dept. of Neurological Surgery, Box 0520, Univ. of California, San Francisco, CA 94143-0520 (E-mail: rturner{at}itsa.ucsf.edu ).