Grant Number: 5R01EY012814-08
Project Title: Neural Organization and Plasticity of the VOR
PI Information: PROFESSOR DORA E. ANGELAKI,
[email protected]
Abstract: DESCRIPTION (provided by applicant):
Vestibulo-ocular reflexes are essential components in the perception and
control of spatial orientation. They are also important for the
perception of the visual world, as well as visually-guided behavior,
since we view the world from a constantly shifting platform and certain
visual mechanisms function optimally only if the images on the retina
are relatively stable. As we go about our everyday activities, visual
and vestibular mechanisms help to stabilize our gaze on objects of
interest, by generating eye movements that offset our head movements.
The traditional approach emphasized mechanisms that deal with rotational
disturbances. More recently, however, it has become clear that a
separate class of vestibulo-ocular reflexes exists (Translational VORs
or TVORs) that represent a phylogenetically recent acquisition in the
evolutionary tree and which appear to have evolved in parallel with
foveal vision, vergence eye movements and stereopsis. This proposal is a
competitive renewal to test specific hypotheses about how sensory
information is centrally processed in order to create motor commands for
the TVOR. We propose novel behavioral experiments aiming at
understanding specific functional hypotheses about the TVOR, as well as
neurophysiological studies to understand the yet unknown neural
processing. Electrophysiological data will be closely accompanied with
theoretical modeling in order to delineate the vestibulo-ocular
computations that underlie the organization of the complex oculomotor
responses during translation. Although motivated by fundamental basic
science issues, the results of this effort will provide a basis for
understanding clinical deficits related to otolith system pathology and
for the development of clinical tests of otolith and vestibulocerebellar
function.
Thesaurus Terms:
head movement, neural information processing, neural plasticity,
neuroanatomy, vestibuloocular reflex, visual pathway
afferent nerve, brain electrical activity, cerebellar Purkinje cell,
cue, fovea centralis retinae, neurophysiology, smooth pursuit eye
movement, visual field
Macaca mulatta, behavioral /social science research tag, vision test
Institution: WASHINGTON UNIVERSITY
1 BROOKINGS DR, CAMPUS BOX 1054
SAINT LOUIS, MO 631304899
Fiscal Year: 2006
Department: ANATOMY AND NEUROBIOLOGY
Project Start: 01-JUL-1999
Project End: 30-JUN-2008
ICD: NATIONAL EYE INSTITUTE
IRG: ZRG1
The Journal of Neuroscience, February 7, 2007, 27(6):1346-1355
A Reevaluation of the Inverse Dynamic Model for Eye
Movements
Andrea M. Green,1 Hui Meng,2
and Dora E. Angelaki2
1D�partement de Physiologie, Universit�
de Montr�al, Montr�al, Qu�bec, Canada H3T 1J4, and 2Department
of Anatomy and Neurobiology, Washington University School of Medicine,
St. Louis, Missouri 63110
Animal preparation.
Four juvenile Macacca mulatta and one Macacca fascicularis monkeys were
prepared for chronic recording of binocular eye movements and
single-unit activities. Each animal was chronically implanted with a
delrin head stabilization ring that was secured to the skull with
inverted stainless steel T bolts. A delrin recording platform
(consisting of a staggered matrix of holes spaced 0.8 mm apart) was
stereotaxically placed inside the ring and served as a guide for
electrode placement. In three of the animals, the platform was implanted
with a 10� lateral/medial slant to allow bilateral access to the
prepositus hypoglossi and abducens/oculomotor nerves and nuclei. Each
animal was also implanted with dual eye coils on both eyes that were
calibrated as explained in detail previously (Angelaki, 1998 ; Angelaki
et al., 2000 ). All surgical procedures were performed under sterile
conditions in accordance with institutional and National Institutes of
Health guidelines.
Experimental set-up.
During experiments, monkeys were seated upright in a primate chair
secured inside a motion delivery system that consisted of a
three-dimensional (3D) vestibular turntable mounted on a linear sled (Acutronics,
Pittsburgh, PA). Binocular eye movements were measured with a
three-field magnetic search coil system (16 inch cube; CNC Engineering,
Seattle, WA) that was attached to the inner gimbal of the vestibular
turntable. Visual targets were back-projected onto a flat screen mounted
20 cm away from the animal. A wall-mounted laser and x�y mirror
galvanometer system (General Scanning, Billerica, MA) provided
world-fixed targets for gaze stabilization during head/body motion. A
second laser-galvanometer system was mounted on top of the vestibular
turntable such that it moved with the animal and provided a head-fixed
target; this enabled evaluation of neural responses to vestibular
stimulation when eye movements were suppressed or cancelled (i.e., VOR
cancellation tasks). The second system was also used to provide visual
targets for fixation and smooth pursuit tasks.
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