Grant Number: 5R01EY000745-35
Project Title: Oculomotor System Studies
PI Information: PROFESSOR OF PHYSIOLOGY & BIOPHYSICS ALBERT F.
FUCHS, fuchs@u.washington.edu
Abstract: DESCRIPTION (provided by applicant):
Adaptation of the amplitude of saccadic eye movements is necessary so
that saccadic accuracy can be maintained throughout life despite the
changes caused by development, injury and aging. The long-term objective
of this grant is to study the mechanism and site(s) of saccadic
amplitude adaptation in non-human primates. We will address this issue
in several ways. First, we will estimate the level of the saccadic
system at which adaptation takes place by determining whether behavioral
adaptation of reactive (more simple) saccades transfers to higher-order
(more "cognitive") saccades. Amplitude adaptation will be produced by
requiring monkeys to track a stepping target that is jumped forward or
backward during a targeting saccade, so that the adaptation mechanism is
deceived into thinking that the saccade is in error. Over approximately
1000 such deceptions, monkeys gradually reduce this error by adjusting
saccade amplitude. If adaptation of a reactive saccade does not transfer
to a higher-order saccade, they must have different sites for saccadic
plasticity. Second, we will record from the oculomotor cerebellar vermis
during behavioral adaptation and assess the associated changes in simple
spike and climbing fiber activity in Purkinje cells. We expect changes
in neuronal firing that will indicate how the saccadic error delivered
by the climbing fibers shapes the simple spike firing of Purkinje cells.
Third, during behavioral adaptation we also will examine the change in
activity of cells in the caudal fastigial nucleus (CFN), which receives
direct inhibition from the vermal Purkinje cells and, in turn, projects
directly to the premotor brain stem generator of saccadic eye movements.
We expect that changes in firing of CFN cells will be appropriate to
effect downstream structures to alter saccade amplitude. Because of the
remarkable similarities of simian and human saccadic behavior, the
results of these experiments should have considerable relevance in the
diagnosis, treatment and rehabilitation of human patients with chronic
saccadic disorders.
Thesaurus Terms:
neural information processing, saccade, visual pathway, visual tracking
behavior test, brain stem, cerebellar Purkinje cell, cerebellum,
environmental adaptation, neural plasticity, neuroregulation, oculomotor
nerve, pons, superior colliculus, visual feedback, visual field, visual
stimulus Macaca mulatta, behavioral /social science research tag
Institution: UNIVERSITY OF WASHINGTON
Office of Sponsored Programs, SEATTLE, WA 98105
Fiscal Year: 2006
Department: PHYSIOLOGY AND BIOPHYSICS
Project Start: 01-SEP-1976
Project End: 30-APR-2009
ICD: NATIONAL EYE INSTITUTE
IRG: CVP
J Neurophysiol 97: 618-634, 2007. First published
October 25, 2006; doi:10.1152
Contribution of the Frontal Eye Field to Gaze Shifts in the
Head-Unrestrained Monkey: Effects of Microstimulation
Thomas A. Knight1,3 and Albert F. Fuchs1,2,3
1Graduate Program in Neurobiology and
Behavior, 2Department of Physiology and
Biophysics, and 3Washington National
Regional Primate Research Center, University of Washington, Seattle,
Washington
Submitted 9 March 2006; accepted in final form 21 October 2006
General procedures
These experiments were performed with two male rhesus monkeys, Macaca
mulatta (weight 4–9 kg). During asceptic surgery, a scleral search coil
for measuring gaze position in space was implanted on each monkey’s left
eye (Fuchs and Robinson 1966 ) and a similar coil for measuring head
position in space was mounted on the head in the coronal plane, just
anterior to the axis of horizontal head rotation. We implanted a
magnetic resonance imaging (MRI)–compatible recording cylinder (Crist
Instruments, Damascus, MD) over each FEF in the first animal and over
the right FEF in the second animal. During experimental sessions, each
animal sat in a primate chair, which restricted its upper body
rotations, and made gaze shifts from one target position to another with
the head completely unrestrained. The chair was placed in a dark
sound-deadened booth and the animal’s condition was monitored with an
infrared video system.
Experimental procedures
Each animal was trained to make normal, visually guided gaze shifts to a
step change in target position between two sequentially (within 5 ms)
illuminated light-emitting diodes (LEDs) on an array in front of the
animal (LED spacing every 1° of visual angle, ±80° horizontally, ±30°
vertically and obliquely). If the gaze shift landed within a reward
window surrounding the illuminated (target) LED, the animal received an
applesauce reward.
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