PARIETAL CORTEX AND SPATIAL-POSTURAL TRANSFORMATION DURING ARM MOVEMENTS.
M.F.S. Rushworth, H. Johansen-Berg, S.A. Young.
Department of Experimental Psychology, University of Oxford, Oxford, OX1
3UD, UK.
APStracts 4:163N, 1997.
ABSTRACT
Cells in the parietal motor areas 5, MIP, and 7b have spatially tuned activity
during movements. Lesions, however, do not disrupt visual reaching or learned
non-spatial movement selection. The role of such parietal cells in
sensorimotor coordinate transformations is unclear. The present experiment
investigates whether the parietal motor areas are concerned with: 1) the
transformation between the desired position in space of the hand and the
limb's postural configuration during movement; 2) inter-joint coordination.
Six macaque monkeys were trained to reach in the dark. Spatial-postural
transformations assume a simple form in the absence of vision and so may be
most easily studied when animals reach in the dark. A lesion was placed in the
parietal cortex that included areas 5, 7b and MIP of three macaques. The
simple relation between hand position and limb postural configuration seen in
controls was disrupted after the lesion. The inter-coordination of movements
of the hand with those of the rest of the arm was also affected. The lesion
did not affect the range or velocity of joint movements or the curvature of
the hand's trajectory. The cell activity in parietal areas 5, 7b, and MIP may
not be essential for the transformation between retinocentric representation
of the target and shoulder centred representations of the desired position of
the hand, but it is essential for both the subsequent transformation between
desired hand position and the postural configuration of the arm and for inter-
joint integration.
Received 7 May 1997; accepted in final form 21 July 1997.
APS Manuscript Number J364-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997