Are visual texture-selective areas recruited during haptic texture discrimination?
43.508, Monday, May 13, 8:30 am - 12:30 pm, Vista Ballroom
Samantha Podrebarac1, Melvyn Goodale2, Jacqueline Snow2; 1Graduate Program in Neuroscience, The Brain and Mind Institute, Natural Sciences Centre, The University of Western Ontario, London, ON, Canada, N6A 5B7., 2The Brain and Mind Institute, Natural Sciences Centre, The University of Western Ontario, London, ON, Canada, N6A 5B7.
Shape and surface texture provide salient cues to object identity, both when objects are explored using vision and via touch (haptics). In vision, shape information is processed within the lateral occipital complex (LOC), while surface texture is selectively processed in medial ventro-temporal cortex, in the collateral sulcus (CoS) and parahippocampul gyrus (pHG). Accumulating evidence indicates that the LOC, despite its location within the ventral visual system, is also consistently recruited during haptic shape processing. Here we used fMRI to examine whether ventral visual texture-selective areas are similarly recruited when observers discriminate surface texture via touch. We used a blocked design in which participants attended to, and made same/different judgments about, sequential pairs of 3-dimensional plastic objects. During each block, the stimuli varied either in their shape (but not surface texture), or their surface texture (but not shape). In half of the scans, participants explored the stimuli using vision alone, and in the remaining scans the stimuli were explored via touch alone. In vision, the strongest fMRI responses to surface texture (versus shape) perception were observed within medial ventral temporal cortex a result consistent with recent fMRI findings in vision. When stimuli were explored via touch, however, the strongest fMRI responses to surface texture (versus shape) perception were observed dorsally, within the parietal operculum (in the vicinity of secondary somatosensory cortex) and inferior frontal cortex. Importantly, however, we also observed significant texture-selective fMRI responses in medial ventral temporal cortex within areas analogous to those recruited during visual texture discrimination. Our imaging data demonstrate for the first time that ventro-medial temporal areas known to process visual textures are also recruited during the perception of surface texture via touch.