Distribution of colour-selective activity in the monkey inferior temporal cortex revealed by functional magnetic resonance imaging

Authors

  • Takuya Harada,

    1. Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    2. Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
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    • *

      T.H. and N.G. contributed equally to this work.

  • Naokazu Goda,

    1. Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    2. Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
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    • *

      T.H. and N.G. contributed equally to this work.

  • Tadashi Ogawa,

    1. Department of Integrative Brain Science, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan
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  • Minami Ito,

    1. Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    2. Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
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  • Hiroshi Toyoda,

    1. Department of Cerebral Research, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    2. Japan Science and Technology Corporation/Research Institute of Science and Technology for Society, Kawaguchi 332-0012, Japan
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  • Norihiro Sadato,

    1. Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
    2. Department of Cerebral Research, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    3. Japan Science and Technology Corporation/Research Institute of Science and Technology for Society, Kawaguchi 332-0012, Japan
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  • Hidehiko Komatsu

    1. Department of Information Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
    2. Department of Physiological Sciences, The Graduate University for Advanced Studies (SOKENDAI), Okazaki 444-8585, Japan
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Dr N. Goda, 1Department of Information Physiology, as above.
E-mail: ngoda@nips.ac.jp

Abstract

Previous electrophysiological, neuroimaging and lesion studies have suggested that the anterior part of the monkey inferior temporal (IT) cortex, or area TE, plays an important role in colour processing. However, little is known about how colour information is distributed in these cortical regions. Here, we explored the distribution of colour-selective activity in alert macaque monkeys using functional magnetic resonance imaging (fMRI) with two types of stimuli: a multicoloured (‘Mondrian’) pattern and an isoluminant colour grating. These two types of stimuli are both commonly used in human fMRI studies, but Mondrian stimuli, which contain a richer variety of hues and hence might be more suitable for activating higher-order areas than grating stimuli, have not been used to examine colour-selectivity in higher-order areas in earlier monkey studies. With the Mondrian stimuli, we observed that areas along the ventral pathway, V1, V2/V3, V4 and the IT cortex, responded more strongly to colour stimuli than to luminance stimuli. In the IT cortex, we found that colour-selective activities are not distributed uniformly, but are localized in discrete regions, each extending several millimetres in the anterior or posterior part of the IT cortex. The colour-selective activation in the anterior IT was observed only with the Mondrian stimuli, whereas the colour-selective activation in the posterior IT was observed with both the Mondrian and grating stimuli, with little overlap. These findings suggest that there are multiple subregions with differing stimulus selectivities distributed in the IT cortex, and that colour information is processed in these discrete subregions.

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