The Journal of Neuroscience, December 15, 2000, 20(24):9310-9319
Neural Responses in the Retinotopic Representation of the Blind
Spot in the Macaque V1 to Stimuli for Perceptual Filling-In
Hidehiko
Komatsu,
Masaharu
Kinoshita, and
Ikuya
Murakami
Laboratory of Neural Control, National Institute for Physiological
Sciences, Myodaiji, Okazaki-shi, Aichi, 444-8585 Japan
When visual stimuli that cover the entire blind spot are presented
monocularly, the color and brightness of the surrounding field are seen
within the blind spot, although it receives no retinal input. Important
questions about such perceptual filling-in are whether neurons in the
visual system representing visual field locations within the blind spot
are activated when filling-in occurs and, if so, what the properties of
these neurons are. To address these questions, we recorded the
activities of single neurons in the primary visual cortex (V1) of the
awake monkey. We first identified the area of V1 representing the
region of the blind spot and then assessed neural responses to
stationary visual stimuli of various size. We found that there are
neurons in layer 4 and deeper laminae, particularly layer 6, that
respond to large stimuli covering the blind spot which induces
perceptual filling-in. Most of these neurons had very large binocular
receptive fields that extended outside the blind spot. These neurons
also preferred relatively large stimuli and exhibited color
selectivity. These results indicate that when a large uniform surface
is presented on the blind spot, neurons at the V1 region representing
the blind spot transmit signals essential for filling-in that inform of the presence of a large surface as well as the absence of smaller stimuli at the blind spot.
Key words:
filling-in; blind spot; V1; monkey; surface perception; completion; visual perception
Copyright © 2000 Society for Neuroscience 0270-6474/00/20249310-10$05.00/0
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