手触りと“眼触り”の脳を探る

Human Brain Representations of Haptic and Visual Textures

筆者らが行っている眼と手による質感を探る脳機能イメージングを紹介する。布を見たときと触ったときの脳画像から見えてきたのは質感のクロスモーダル性だった。見ていた布は視覚野だけでなく触覚野の活動からも解読できた。触っていた布は触覚野だけでなく視覚野でも解読できた。さらに，眼でも手でも質感が区別できる領域が連合野と感覚野に見つかった。眼で触り手で見るかのような脳の振る舞いは質感の感性面の顕れかもしれない。

Abstract

We present a literature review of functional brain imaging studies of haptic and visual texture perception, and highlight our ongoing functional magnetic resonance imaging (fMRI) experiment of the crossmodal links between vision and touch. In the fMRI experiment, the subjects viewed or touched a piece of wool or denim cloth. A multivoxel pattern analysis of whole-brain fMRI activity revealed the crossmodal nature of natural texture perception. Visual texture representations were found in the somatosensory and association cortices as well as the visual cortex, while haptic texture representations were found in the visual cortex and association cortices as well as the somatosensory cortex. Furthermore, shared visuo-haptic representations were found in the parietal association, somatosensory, and visual cortices. These results that suggested the crossmodal transfer of texture information across functionally segregated sensory and associative brain regions are discussed in relation to previous findings on texture perception and aesthetic texture or shitsukan.