Feeling with the mind's eye: the role of visual imagery in tactile perception.

Cross-modal interactions are characteristic of normal perception. In this article, we discuss our work on cross-modal interactions between touch and vision in normally sighted humans. A region of extrastriate visual cortex, near the parieto-occipital fissure, is not only active during but also necessary for tactile discrimination of grating orientation (but not spatial frequency). This is consistent with a role for visual imagery in certain aspects of tactile perception. These findings have implications for the interpretation of visual cortical involvement in Braille reading by the blind.