Stimulus-specific competitive selection in macaque extrastriate visual area V4
- *Systems Neurobiology Laboratory and
- ‡Vision Center Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037
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Communicated by Robert Desimone, Massachusetts Institute of Technology, Cambridge, MA, January 4, 2007 (received for review February 21, 2006)
Abstract
Macaque visual area V4 has been implicated in the selective processing of stimuli. Prior studies of selection in area V4 have used spatially separate stimuli, thus confounding selection of retinotopic location with selection of the stimulus at that location. We asked whether V4 neurons can selectively respond to one of two differently colored stimuli even when they are spatially superimposed. We find that delaying one of the two stimuli leads to selective processing of the delayed stimulus by area V4 neurons. This selective processing persists when the stimuli move together across the visual field, thereby successively activating different populations of neurons. We also find that this effect is not a spatially global form of feature-based selection. We conclude that selective processing in area V4 is neither exclusively spatial nor feature-based and may thus be surface- or object-based.
Footnotes
- †To whom correspondence should be sent at the present address: School of Kinesiology and Health Science Centre for Vision Research, York University, 4700 Keele Street, Toronto, ON, Canada M3J 1P3 . E-mail: mfallah{at}yorku.ca
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Author contributions: M.F., G.R.S., and J.H.R. designed research; M.F. performed research; M.F., G.R.S., and J.H.R. analyzed data; and M.F., G.R.S., and J.H.R. wrote the paper.
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The authors declare no conflict of interest.
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This article contains supporting information online at www.pnas.org/cgi/content/full/0611722104/DC1.
- Abbreviation:
- CRF,
- classical receptive field;
- dva,
- degrees of visual arc;
- MI,
- modulation index;
- NMI,
- normalized MI.
- © 2007 by The National Academy of Sciences of the USA
