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Grant Number: 5R01EY015271-03
Project Title: Studies of Three-Dimensional Ocular Kinematics
PI Information: PROFESSOR DORA E. ANGELAKI,
angelaki@pcg.wustl.edu
Abstract: DESCRIPTION (provided by applicant):
Strabismus, the misalignment of the two eyes, is a disorder of unknown
etiology, caused by problems related to either the central innervation
sent to the eye muscles and/or the eye muscles and orbital tissues
themselves. Improving our understanding of the central and peripheral
aspects of eye movement control is an important and necessary first step
for an effective clinical diagnosis and treatment of strabismus
patients. Our understanding of how the brain controls eye movements has
benefited enormously from the comparison of neuronal activity with eye
movements and the quantification of these relationships with
mathematical models. Whereas this task has been very successful when
considering eye movements in a single direction, mainly uncertainty,
controversy and conflicting hypotheses currently exist when considering
oculomotor control in three-dimensions. Part of the problem arises
because arguments related to these controversies have been largely
limited to behavioral observations. Very little data currently exist
regarding the discharge properties of motor and premotor neurons for
oculomotor control in 3D. Such a paucity of neurophysiological data
includes the recent histological discovery of extraocular muscle pulleys
and their postulated role in 3D eye movements (active pulley
hypothesis). The long-term goal of these studies is to characterize
neural activity during eye movements in 3D and to quantify these
relationships with existing or expanded mathematical models of the
oculomotor system. In this application, we propose a systematic series
of experiments that, for the first time, will provide the missing link
between behavior, imaging and modeling in understanding the role of
mechanical and neural factors in 3D eye movement control. Accordingly,
single unit recordings from motoneurons and premotor neurons during
saccades, pursuit and the VOR will attempt to provide a comprehensive
data set upon which existing and revised models of oculomotor function
in 3D will be evaluated. Results from these experimental/modeling
studies are fundamental in resolving these controversies and providing a
comprehensive understanding of oculomotor function in health and
disease.
Thesaurus Terms:
biomechanics, disease /disorder etiology, extraocular muscle, eye
coordination disorder, eye movement, motor neuron, neurophysiology,
vestibuloocular reflex oculomotor nerve, saccade, single cell analysis,
three dimensional imaging /topography Macaca mulatta
Institution: WASHINGTON UNIVERSITY
1 BROOKINGS DR, CAMPUS BOX 1054
SAINT LOUIS, MO 631304899
Fiscal Year: 2006
Department: ANATOMY AND NEUROBIOLOGY
Project Start: 01-AUG-2004
Project End: 31-JUL-2008
ICD: NATIONAL EYE INSTITUTE
IRG: SMI
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
1Département de Physiologie, Université
de Montréal, Montréal, Québec, 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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