Abstract
The impression of surface gloss defines important properties of objects that can influence diverse behaviors. Recent progress has been made in understanding the monkey cortical areas that respond to gloss (Nishio, et al., 2012; Okazawa, et al., 2012), however, the network of areas in the human brain remains unclear. We used fMRI measurements to localize brain areas preferentially responding to glossy objects. We used Blender to render 32 nonsense objects as either Lambertian or having a specular component to their surfaces. We used spatially scrambled versions of the stimuli to control for low-level image differences. This scrambling was based on superimposing a grid over the images and then randomly relocating squares from within the grid. There were four conditions: glossy, scrambled glossy, matte and scrambled matte. Fifteen participants took part in a block-designed fMRI session and performed 1-back matching task on the images. Functional MRI activations were measured over the whole brain with echo-planar imaging (EPI) sequence (32 slices, TR 2000 ms, TE 35 ms, voxel size 2.5 × 2.5 × 3 mm) and a 32-channel head coil. We analyzed the data using a general linear model (GLM). We found that activations related to gloss were mainly observed along ventral visual areas in both hemispheres. Activations in fusiform gyrus (FG), collateral sulcus (CoS) and kinetic-occipital (KO) region were significantly stronger in glossy condition than the other three conditions, suggesting a preference for glossy surfaces. These areas are consistent with previous reports of activity in the FG and CoS related to the perception of object material properties (Cant, et al., 2009; Cant & Goodale, 2007; Hiramatsu, et al., 2011). Thus, our results suggest a small network of ventral areas whose activity may be important in supporting our perception of material properties in general, and surface gloss in particular.
Meeting abstract presented at VSS 2014