Summary of Research Project Results Under the JSPS FY2000
"Research for the future Program"



1.Research Institution Okazaki National Research Institutes
 
2.Research Area Life Science
 
3.Research Field Higher Brain Functions
 
4.Term of Project FY1996〜FY2000
 
5.Project Number 96L00202
 
6.Title of Project Neural mechanisms of visual cognition in the cerebral Cortex

7.Projetct Leader
Name Institution,Department Title of Position
Komatsu Hidehiko Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Professor

8.Core Members

Names Institution,Department Title of Position
Ito Minami Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Associate Professor
Hanazawa Akitoshi Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Research Associate
Ogawa Tadashi Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Research Associate

9.Cooperating Researchers

Names Institution,Department Title of Position
Murakami Ikuya Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Research Fellow
Kinoshita Masaharu Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Research Associate
Koida Kowa Okazaki Natl. Res. Inst, Inst. for Physiol. Sci Research Associate

10.Summary of Research Results

1. We have shown that non-linear processing of cone signals takes place in the primary visual cortex (V1) of the macaque monkey that generate neurons sharply tuned for hue and saturation of color. This indicates that V1 plays vital role in the formation of color representation observed in the higher visual areas. 2. Macaques lacking one type of cone pigment were detected for the first time. ERG recording have confirmed that sensitivity to red lights is extremely low in these monkeys compared with normals. 3. Neurons were found in are V4 that were specifically sensitive to particular 3-dimensional (3D) surface textures. These neurons responded to texture patterns consisting of many fine shading patterns and were sensitive to the density, size and direction of shading. A bias in the preferred shading direction was consistent with a bias observed in human perception in shape from shading. These results strongly suggest that V4 is involved in perception of 3D surface textures. 4. We found that neurons in area MSTd systematically represent 3D orientation of a surface defined by moving random dots. These neurons integrate information of various directions and velocities across surface stimuli and seem to be involved in the process of recovering surface orientation from moving stimuli. 5. We found that neurons in the retinotopic representation of the blind spot in V1 are activated when perceptual filling-in occurs at the blind spot even though there is no retinal input to this area. It was suggested that spatial aspects of stimuli presented on the blind spot are represented as the difference in the activities across neurons with different spatial properties. 6. We found that neurons exist in V1 that encode the luminance of homogeneous surfaces that cover the receptive field. Some of these neurons were modulated by the luminance of the surround and exhibited activity which parallels with the brightness perception of the surface. This indicates that spatial integration of luminance information occurs in V1.

11.Key Words

(1)Vison、(2)Cerebral Cortex、(3)Monkey
(4)Perception、(5)Color、(6)Texture
(7)Motion、(8)Filling-in、(9)Cognition

12.References

[Reference Articles]
Author Title of Article
Komatsu, H. Mechanisms of central color vision.
Journal Volume Year Pages Concerned
Current Opinion in Neurobilogy 8 1998 503-508

Author Title of Article
Onishi. A. et al Dichromatism in macaque monkeys.
Journal Volume Year Pages Concerned
Nature 402 1999 139-140

Author Title of Article
Kondo, H. and Komatsu, H. Suppression on neuronal responses by a metacontrast masking stimulus in monkey V4.
Journal Volume Year Pages Concerned
Neuroscience Research 36 2000 27-33

Author Title of Article
Hanazawa, A. et al Neural selectivity for hue and saturation of colour in the primary visual cortex of the monkey.
Journal Volume Year Pages Concerned
European J. Neuroscience 12 2000 1753-1763

Author Title of Article
Komatsu, H. et al Neural responses in the retinotopic representation of the blind spot in the macaque V1 to stimuli for perceptual fining - in.
Journal Volume Year Pages Concerned
J. Neuroscience 20 2000 9310-9319

Author Title of Article
Hanazawa, A. and Komatsu, H. Influence of the direction elemental luminance gradients on the responses of V4 cells to textured surfaces.
Journal Volume Year Pages Concerned
J. Neuroscience   2001 in press

[Reference Books]
Author Title of Book
Komatsu, H. Neural representation of color in the inferior temporal cortex of the macaque monkey. in: The Association Cortex-Sfrucfure and Functions
Publisher Year Pages
Harwood academic publishers 1997 pp269-280

Author Title of Book
Komatsu, H. The physiological substrates of color constancy. In: Perceptual Constancy
Publisher Year Pages
Cambridge University Press 1998 pp352-372


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