Müller, K.-M. and Wilke, M. and Leopold, D. A. (2009) Visual adaptation to convexity in macaque area V4. Neuroscience, 161 (2). pp. 655-662. ISSN 0306-4522 http://resolver.caltech.edu/CaltechAUTHORS:20090827-142528326
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Aftereffects are perceptual illusions caused by visual adaptation to one or more stimulus attribute, such as orientation, motion, or shape. Neurophysiological studies seeking to understand the basis of visual adaptation have observed firing rate reduction and changes in tuning of stimulus-selective neurons following periods of prolonged visual stimulation. In the domain of shape, recent psychophysical work has shown that adaptation to a convex pattern induces a subsequently seen rectangle to appear slightly concave. In the present study, we investigate the possible contribution of V4 neurons of rhesus monkeys, which are thought to be involved in the coding of convexity, to shape-specific adaptation. Visually responsive neurons were monitored during the brief presentation of simple shapes varying in their convexity level. Each test presentation was preceded by either a blank period or several seconds of adaptation to a convex or concave stimulus, presented in two different sizes. Adaptation consistently shifted the tuning of neurons away from the convex or concave adapter, including shifting response to the neutral rectangle in the direction of the opposite convexity. This repulsive shift resembled the known perceptual distortion associated with adaptation to such stimuli. In addition, adaptation caused a nonspecific response decrease, as well as a specific decrease for repeated stimuli. The latter effects were observed whether or not the adapting and test stimuli matched closely in their size. Taken together, these results provide evidence for shape-specific adaptation of neurons in area V4, which may contribute to the perception of the convexity aftereffect.
|Additional Information:||© 2009 IBRO. Accepted 30 March 2009. Available online 5 April 2009. We thank our collaborators: N. Phipps and K. Smith for assistance with animal training and experimentation; C. Zhu and Dr. F. Ye for help with MRI scans; Dr. D. Sheinberg for providing some of the stimulation software; Dr. A. Maier and Dr. D. McMahon for insightful suggestions concerning data acquisition, analysis, and previous versions of this manuscript. This work was supported by the Intramural Research Programs of NIMH, NINDS and NEI at the National Institutes of Health.|
|Subject Keywords:||visual perception; visual cortex; area V4; electrophysiology; adaptation; visual aftereffects|
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|Deposited By:||Tony Diaz|
|Deposited On:||11 Sep 2009 23:50|
|Last Modified:||26 Dec 2012 11:15|
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