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Stop Animal
Exploitation NOW!
S. A. E. N.
"Exposing the truth to wipe
out animal experimentation"
Government Grants Promoting Cruelty to Animals
Washington University, St. Louis, MO
GREGORY C. DEANGELIS - Primate Testing - 2006
Grant Number: 2R01EY013644-06
Project Title: Neural Basis of Depth Perception
PI Information: ASSOCIATE PROFESSOR GREGORY C. DEANGELIS,
[email protected]
Abstract: DESCRIPTION (provided by applicant):
We interact almost effortlessly with objects in our three-dimensional
(3D) visual environment, yet the image formed on the retina of each eye
is simply a two-dimensional projection of 3D space that contains no
explicit information about depth. Thus, a fundamental task of the visual
system is to reconstruct 3D scene structure from the images formed on
the retina of each eye. Quantitative information about depth is mainly
carried by two visual cues: binocular disparity and motion parallax. The
overall goal of this research is to understand where and how these depth
cues are processed by neurons in the visual cortex to mediate our
perception of a 3D world. This proposal describes experiments that
address two fundamental issues regarding the neural basis of depth
perception. In Aim #1, we will use a reversible inactivation technique
to explore the roles that the dorsal and ventral visual processing
streams make to stereoscopic depth perception. By inactivating areas MT
and V4, we will test the hypothesis that the dorsal stream mainly
processes absolute disparities to compute the location of objects in 3D
space, whereas the ventral stream mainly processes relative disparities
to compute 3D shape and fine depth structure. In Aim #2, we will carry
out the first neurophysiological studies of how the visual system
computes depth from motion parallax. Motion parallax resulting from
movement of the observer is fundamentally ambiguous regarding the sign
of depth (near versus far relative to the point of fixation). As a
result, motion parallax generally must be combined with extraretinal
signals to compute depth sign. We will test whether neurons in area MT
combine retinal image motion with extraretinal signals to compute depth
from motion parallax, and we will explore the origins of the
extraretinal signals involved in this process. This research addresses
the fundamental issue of how neural activity gives rise to visual
perception, and also explores how extraretinal signals interact with
visual processing to carry out interesting computations in the brain.
Thus, this work addresses one of the Program Goals of the National Eye
Institute's National Plan for Eye and Vision Research. The ultimate
health-related value of this work will follow from a deeper
understanding of how cognitive functions can be explained in terms of
neural activity. Understanding the links between brain activity and
mental function in normal observers will provide a deeper appreciation
of the causes of various mental disorders.
Thesaurus Terms:
binocular vision, neural information processing, visual cortex, visual
depth perception
motion perception, neuron, visual field, visual stimulus
Macaca mulatta, behavioral /social science research tag, electrostimulus,
microelectrode, single cell analysis
Institution: WASHINGTON UNIVERSITY
1 BROOKINGS DR, CAMPUS BOX 1054
SAINT LOUIS, MO 631304899
Fiscal Year: 2006
Department: ANATOMY AND NEUROBIOLOGY
Project Start: 05-JUL-2001
Project End: 30-JUN-2007
ICD: NATIONAL EYE INSTITUTE
IRG: CVP
The Journal of Neuroscience, January 17, 2007, 27(3):700-712
Spatial Reference Frames of Visual, Vestibular, and
Multimodal Heading Signals in the Dorsal Subdivision of the Medial
Superior Temporal Area
Christopher R. Fetsch, Sentao Wang, Yong Gu, Gregory C. DeAngelis, * and
Dora E. Angelaki *
Department of Anatomy and Neurobiology, Washington University School of
Medicine, St. Louis, Missouri 63110
Animal preparation.
Subjects were three male rhesus monkeys (Macaca mulata) weighing 4�7 kg.
Under sterile conditions, monkeys were chronically implanted with a
circular delrin cap for head stabilization as described previously (Gu
et al., 2006a ), as well as one or two scleral search coils for
measuring eye position (Robinson, 1963 ; Judge et al., 1980 ). After
surgical recovery, monkeys were trained to fixate visual targets for
juice rewards using standard operant conditioning techniques. Before
recording experiments, a plastic grid (2 x 4 x 0.5 cm) containing
staggered rows of holes (0.8 mm spacing) was stereotaxically secured to
the inside of the head cap using dental acrylic. The grid was positioned
in the horizontal plane and extended from the midline to the area
overlying the MSTd bilaterally. Vertical microelectrode penetrations
were made via transdural guide tubes inserted in the grid holes. All
procedures were approved by the Institutional Animal Care and Use
Committee at Washington University and were in accordance with National
Institutes of Health guidelines.
Heading stimuli.
During experiments, monkeys were seated comfortably in a primate chair
with their head restrained. The chair was secured to a
6-degrees-of-freedom motion platform (MOOG 6DOF2000E; Moog, East Aurora,
NY) (see Fig. 1A) that allowed physical translation along any axis in 3D
(Gu et al., 2006a ). Visual stimuli and fixation targets were
back-projected (Christie Digital Mirage 2000; Christie, Cyrus, CA) onto
a tangent screen positioned 30 cm in front of the monkey and subtending
90� x 90� of visual angle. Optic flow was generated using the OpenGL
graphics library, allowing the accurate simulation of speed, size, and
motion parallax cues experienced during real self-motion. The stimuli
depicted movement of the observer through a random cloud of dots plotted
in a virtual workspace 100 cm wide, 100 cm tall, and 40 cm deep. Stimuli
were viewed binocularly with no disparities added to the display (i.e.,
no stereo cues were present). The projector, screen, and field coil
frame were mounted on the platform and moved along with the animal, and
the field coil frame was enclosed such that the animal experienced no
visual motion other than the optic flow presented on the screen.
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Please email: GREGORY C.
DEANGELIS,
[email protected] to protest the inhumane use of animals in this
experiment. We would also love to know about your efforts with this
cause:
[email protected]
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Rats, mice, birds, amphibians and other animals have
been excluded from coverage by the Animal Welfare Act. Therefore research
facility reports do not include these animals. As a result of this
situation, a blank report, or one with few animals listed, does not mean
that a facility has not performed experiments on non-reportable animals. A
blank form does mean that the facility in question has not used covered
animals (primates, dogs, cats, rabbits, guinea pigs, hamsters, pigs,
sheep, goats, etc.). Rats and mice alone are believed to comprise over 90%
of the animals used in experimentation. Therefore the majority of animals
used at research facilities are not even counted.
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