Abstract
Background: Previous studies have shown that word processing involves a predominantly left-sided occipitotemporal network. Words are a form of symbolic representation, in that they are arbitrary perceptual stimuli that represent other objects or concepts. Patients with alexia can have problems processing other types of symbols, such as musical notation. Whether other symbolic visual representations are processed similarly to visual words is not known. Objective: We determined whether there were any occipitotemporal regions that showed an overlap in processing a number of different visual symbolic classes. Method: 16 right-handed music-literate subjects took part in an fMRI study designed to examine the response in occipitotemporal cortex to other forms of symbolic representations. We examined four symbolic categories: a) words, b) musical symbols, c) traffic symbols, and d) flags and logos. BOLD signal during perception of these categories was contrasted with activity related to 1) their spatially scrambled equivalents, and 2) pseudo-symbolic equivalents, which were similar stimuli that lacked symbolic context. Results: The right and left VWFA responded to words, musical annotations, and traffic symbols; however, these areas also responded to pseudo-symbolic equivalents. Rather, greater response to symbolic than pseudo-symbolic stimuli was seen in the left inferior temporal gyrus (ITG) and middle temporal gyrus (MTG). A whole brain analysis comparing the response to symbolic versus pseudo-symbolic stimuli revealed a distributed network of inferior temporooccipital and parietal regions responding to the different categories. Conclusion: The regions involved in processing visual words, including the VWFA, the left ITG, and left MTG, also play a role in processing not just words but also some forms of symbolic representations, particularly musical notation.
Meeting abstract presented at VSS 2014