University of California, Davis CA

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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

University of California, Davis CA

KENNETH H. BRITTEN - Primate Testing - 2006

Grant Number: 5R01EY010562-11
Project Title: Hierarchical Processing in the Motion System
PI Information: KENNETH H. BRITTEN,  khbritten@ucdavis.edu,
Phone: (530) 754-5080  Fax: (530) 757-8827

Abstract: DESCRIPTION (provided by applicant):
The basic "building blocks" of visual perception are starting to become reasonably well understood, and we can make a fairly good account of how simple discriminations are done.

What we understand much less is how the visual system solves more realistic, everyday challenges. Visually guided navigation is a particularly good "model system" for studying real-world visual processes in the laboratory. The perception of self-motion from the pattern of motion on the retina has been studied extensively, though we still know very little about where in the brain the critical processing steps occur, and how the complex pattern of motion is converted into effective movement.

The present proposal seeks to answer these open questions. First, we will seek direct evidence for the involvement of multiple cortical areas in the perception of self-motion, by using multiple, simultaneous recording techniques while our experimental animals are performing a discrimination of self-motion direction.

Secondly, we will seek to ask if the parietal cortical area (the ventral intraparietal area or VIP) is both necessary for self-motion perception and is actually used. We will do this by perturbing the pattern of activity in VIP in the context of the self-motion task, both by reversible inactivation as well as by electrical activation.

These complementary methods should greatly extend our understanding of how the parietal cortex participates in self-motion perception. However, to really extend our knowledge of self-motion perception, we need to extend the inquiry into a more active context. Human-factors studies have revealed that guidance of self-motion ("steering") is a very active process, with the direction of gaze being a critical component. However, next to nothing is known about the central nervous system mechanisms used in this active task.

So, we propose to establish, characterize and exploit an animal model of active locomotion to study the involvement of brain structures in this task. We will train our subject to direct their "virtual" trajectories by joystick, and characterize how their normal behavior is influenced by cues including target direction, gaze direction, gaze velocity, and visual motion information.

We will then record activity in multiple cortical areas while animals are engaged in this task, and explore the signals in visual and parietal cortex to better understand brain mechanisms of visually guided navigation. This information, in the long term, might be useful in helping the disabled to navigate, and in the development of visual prosthetics for the blind.

Thesaurus Terms:
motion perception, neural information processing, neuropsychology, parietal lobe /cortex, visual cortex, visual perception chordate locomotion, computational neuroscience, cue, eye movement, sensorimotor system
Macaca mulatta, behavior test, behavioral /social science research tag, single cell analysis
 
Institution: UNIVERSITY OF CALIFORNIA DAVIS
OFFICE OF RESEARCH - SPONSORED PROGRAMS
DAVIS, CA 95618
Fiscal Year: 2006
Department: CENTER FOR NEUROSCIENCE
Project Start: 01-APR-1994
Project End: 31-DEC-2009
ICD: NATIONAL EYE INSTITUTE
IRG: CVP

J Neurophysiol 88: 3469-3476, 2002; doi:10.1152/jn.00276.2002
0022-3077/02 $5.00
J Neurophysiol (December 1, 2002);10.1152/jn.00276.2002
Submitted on 2 April 2002 Accepted on 13 August 2002

Motion Adaptation in Area MT
 
Richard J. A. Van Wezel and Kenneth H. Britten
University of California, Davis Center for Neuroscience and Section of Neurobiology, Physiology, and Behavior, Davis, California 95616

Preparation and recordings
We recorded single MT cells in three adult female rhesus monkeys (Macaca mulatta). Before recording, each monkey had been trained to fixate a stationary red spot of 0.23 diam in the presence of visual stimuli. The animal's fluid intake was restricted, and behavioral control was achieved using operant conditioning techniques. The animal received a fluid reward (a drop of water or juice) for keeping its eyes within a window (1-2.5 width) surrounding the fixation point for the duration of the trial.

All surgical and experimental methods followed previously described procedures (Britten et al. 1992 ), conformed to the National Institutes of Health Guide for the Care and Use of Laboratory Animals, and were approved by the UC Davis Animal Care and Use Committee.

Under deep surgical anesthesia, each animal was implanted with a scleral search coil (Judge et al. 1980 ) and was equipped with a stainless steel head restraint post and recording cylinder (Crist Instrument, Damascus, MD) located over the occipital cortex. The monkeys were given at least 2 weeks to recover from surgery before recording.

A plastic grid secured inside the cylinder provided a coordinate system of guide tube support holes at 1-mm intervals (Crist et al. 1988 ). Guide tubes were inserted transdurally through these holes, with local anesthetic if necessary. Parylene-insulated tungsten microelectrodes (MicroProbe, Potomac, MD) were inserted through these guide tubes, and neural signals from these electrodes were amplified, filtered, and displayed by standard methods.

Spikes were isolated using a time-amplitude window discriminator (Bak Electronics, Germantown, MD) and converted to voltage pulses that were fed to the computer controlling the experiment. Data acquisition and experimental control were managed by the software package REX (Hays et al. 1982 ). Neurons were determined to be located in MT by physiological criteria: receptive field size, directionally selective responses, columnar organization for preferred directions, and appropriate retinotopic organization (Albright et al. 1984 ; Maunsell and Van Essen 1983b ; Zeki 1974 ).

In two monkeys, we verified histologically that the recording region corresponded to the heavily myelinated zone on the posterior bank of the superior temporal sulcus (STS). This landmark is a very reliable indicator of the location of MT (Desimone and Ungerleider 1986 ; Maunsell and Van Essen 1983a ). This verification is not yet available for the third monkey because it is currently involved in other experiments.
 
Once a single unit was isolated, the receptive field was mapped using hand-controlled stimuli, typically moving bars of light. We only included in our analysis cells that were fully directionally selective, by which we mean that there is no overlap in the response distributions for the preferred and null directions at the highest coherence tested (Britten et al. 1992 ).

This criterion need not imply a DSI [the standard index of directionality, calculated as (pref null)/(pref + null)] near 1.0, nor that the cells be silent in their null direction. Thirteen of 87 cells did not meet this criterion.

We imposed this criterion only for consistency with previous work, but inspection of the excluded cells' data showed that the adaptation effects were very similar as that from the retained cells (data not shown). 

Please email:  KENNETH H. BRITTEN, khbritten@ucdavis.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 . You may also call or fax to:
Phone: (530) 754-5080  Fax: (530) 757-8827

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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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