Motor Adaptation of the Primate Functional Oculomotor Range During Head-
Free Gaze Shifts.
J. Douglas Crawford and Daniel Guitton.
Centre for Vision Research and Departments of Psychology and Biology, York
University, Toronto, Ontario, Canada, M3J 1P3 Montreal Neurological Institute
and Department of Neurology and Neurosurgery, McGill University, Montreal,
Quebec, Canada, H3A 2B4..
APStracts 4:178N, 1997.
ABSTRACT
When we glance between objects, the brain ultimately controls gaze direction
in space. However, it is currently unclear how this is allocated into separate
commands for eye and head movement. To determine the role of desired final eye
position commands, and their coordination with intended head movement, we
trained 3 monkeys to make large gaze shifts while wearing opaque goggles with
a monocular 8ø aperture. Animals eventually developed a new set of context-
dependent eye-head coordination strategies, in particular expanding the head
range and compressing the eye-in-head range toward the aperture (while wearing
the goggles). However, when we shifted the location of the aperture to a
different sub-section of the normal head-free oculomotor range (by covering
the original aperture and creating a new one), eye-head saccades failed to
acquire visual targets, because they continued to drive the eye ultimately
toward the now occluded original aperture. Even when a head-stationary saccade
acquired the new aperture, subsequent head-free saccades drove the eye
eccentrically toward a point that anticipated the intended head movement, such
that the subsequent VOR slow phase brought the eye onto the location of the
original aperture. Animals could only acquire the new aperture consistently
after several days of re-training. These results suggest that (1) eye-head
coordination is achieved by a plastic, context-dependent neural operator that
uses information about initial eye / head position and intended movement to
compute desired combinations of final eye / head position, and (2) acquisition
of these positions involves sophisticated anticipatory compensations for
subsequent movement components, akin to those observed previously in complex
oral and manual behaviours.
Received 11 June 1997; accepted in final form 1 August 1997.
APS Manuscript Number J487-7.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 28 August 1997