Gouki Okazawa

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The surface properties of objects, such as gloss, transparency and texture, provide important information about the material characteristics of objects in our visual environment. However, because there have been few reports on the neuronal responses to surface properties in primates, we still lack information about where and how surface properties are(More)
Our daily visual experiences are inevitably linked to recognizing the rich variety of textures. However, how the brain encodes and differentiates a plethora of natural textures remains poorly understood. Here, we show that many neurons in macaque V4 selectively encode sparse combinations of higher-order image statistics to represent natural textures. We(More)
Information about the material from which objects are made provide rich and useful clues that enable us to categorize and identify those objects, know their state (e.g., ripeness of fruits), and properly act on them. However, despite its importance, little is known about the neural processes that underlie material perception in nonhuman primates. Here we(More)
Humans are able to categorize an infinite variety of surface colors into a small number of color terms. Previous studies have shown that 11 basic color terms are commonly used in fully developed languages. These studies usually used flat matte color plates as stimuli, but we can also perceive the colors of glossy surfaces by discounting the effect of the(More)
Appearance of a color stimulus is significantly affected by the contrast between its luminance and the luminance of the background. In the present study, we used stimuli evenly distributed on the CIE-xy chromaticity diagram to examine how luminance contrast affects neural representation of color in V4 and the anterior inferior temporal (AITC) and posterior(More)
Dichromacy is a color vision defect in which one of the three cone photoreceptors is absent. Individuals with dichromacy are called dichromats (or sometimes "color-blind"), and their color discrimination performance has contributed significantly to our understanding of color vision. Macaque monkeys, which normally have trichromatic color vision that is(More)
Complex shape and texture representations are known to be constructed from V1 along the ventral visual pathway through areas V2 and V4, but the underlying mechanism remains elusive. Recent study suggests that, for processing of textures, a collection of higher-order image statistics computed by combining V1-like filter responses serves as possible(More)
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