Washington University, St. Louis, MO

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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, gregd@cabernet.wustl.edu 

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 47 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.  

Please email:  GREGORY C. DEANGELIS, gregd@cabernet.wustl.edu  to protest the inhumane use of animals in this experiment. We would also love to know about your efforts with this cause: saen@saenonline.org

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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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