Johns Hopkins University, Baltimore, MD

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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

Johns Hopkins University, Baltimore, MD

CHARLES E. CONNOR - Primate Testing - 2006

Grant Number: 5R01EY011797-08
Project Title: Object Synthesis in Extrastriate Visual Cortex
PI Information: ASSOCIATE PROFESSOR CHARLES E. CONNOR, connor@jhu.edu 

Abstract: DESCRIPTION (provided by applicant):
The long-term objective of this research is to better understand the neural code for object shape by quantifying shape representation at the single cell and neural population levels. This objective is addressed by behavioral and neurophysiological studies of shape representation in the ventral (object-related) pathway of macaque visual cortex, specifically at intermediate and higher levels (V4, PIT/TEO, CIT/TE). The experiments utilize large, parametric shape stimulus sets to define neural tuning functions in shape-related dimensions such as contour curvature. The same stimuli are used for all cells to enable reconstruction of population responses. Three specific aims are addressed: 1. To test whether shape-tuning functions can predict responses to realistic images of random objects. Photographic images of natural and man-made objects will be used to test the predictive value of tuning functions based on parametric shape stimuli. Preliminary results show that these tuning functions are highly predictive, suggesting that they successfully capture the coding functions of ventral pathway neurons. 2. To reconstruct shape representation at the neural population level in the ventral pathway. Shape is so complex that it can only be represented by a distributed neural code--i.e., by patterns of activity in large neural populations. Standard sets of both parametric and realistic shape stimuli will be used to study large numbers of neurons so that the population-level representations of these stimuli can be reconstructed. Population reconstruction is essential for understanding how neurons cooperate to encode shape information in a distributed fashion. 3. To test for correlation between neural responses and shape perception as revealed at the behavioral level. Neural/behavioral correlations provide the clearest evidence for causal relationships between neural responses and perceptual/cognitive events. Ambiguous shape stimuli will be created by parametric morphing between behavioral target stimuli. Behavioral decisions about ambiguous stimuli will be compared with neural responses during the same trials. Microstimulation will be used to attempt to bias behavioral responses in the direction indicated by local shape tuning.

Thesaurus Terms:
form /pattern perception, neural information processing, visual cortex, visual perception
brain electrical activity, cell population study, perceptual distortion, visual pathway, visual stimulus
Macaca mulatta, behavioral /social science research tag, neuropsychological test

Institution: JOHNS HOPKINS UNIVERSITY
W400 Wyman Park Building
BALTIMORE, MD 212182680
Fiscal Year: 2006
Department: NONE
Project Start: 01-FEB-1999
Project End: 31-AUG-2007
ICD: NATIONAL EYE INSTITUTE
IRG: VISB 

J Neurophysiol 94: 2726-2737, 2005

Quantitative Characterization of Disparity Tuning in Ventral Pathway Area V4

David A. Hinkle and Charles E. Connor

Department of Neuroscience, The Johns Hopkins University School of Medicine and Zanvyl Krieger Mind/Brain Institute, The Johns Hopkins University, Baltimore, Maryland

Submitted 1 April 2005; accepted in final form 20 June 2005

Stereoscopic visual stimuli were generated on an Octane workstation (Silicon Graphics, Mountain View, CA) using OpenGL 1.1 graphics libraries. Images for the left and right eyes were presented in alternate frames. Separate presentation of images for the two eyes was accomplished using a NuVision stereoscopic liquid crystal shutter (MacNaughton, Beaverton, OR) attached to the monitor, and passive circular-polarized lenses placed immediately in front of the monkey's eyes. We compensated for cross talk between the two eye channels by adding to each eye's image a low-contrast, negative version of the opposite eye image. Contrast levels of the negative image for each stimulus color were adjusted manually and verified with a luminance meter. This procedure produced stimuli that were free of any appreciable interference between eye channels.

The scleral coil of fine insulated wire was surgically implanted beneath the conjunctiva of the eye (Judge et al. 1980 ). The coil was attached to the sclera with instant adhesive (Loctite, Rocky Hill, CT) in three locations to prevent slippage. A head-restraint post and recording chamber were implanted in separate surgical procedures. All procedures conformed to the National Institutes of Health and USDA guidelines and were approved by The Johns Hopkins University Animal Care and Use Committee.

Please email: CHARLES E. CONNOR, connor@jhu.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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