Abstract
The visual word form area (VWFA), a small region on the lateral side of the left fusiform gyrus, responds at least twice as strongly to visually presented words and letter strings as it does to other visually similar stimuli, including words in an unfamiliar orthography (e.g. Chinese or Hebrew for English speakers), digit strings, and line drawings of objects (Baker et al., 2007). The VWFA is of particular interest in efforts to understand the functional organization of the ventral visual pathway, and its developmental origins, because reading is a recent cultural invention (on the scale of human evolution) so it is unlikely that specialization for reading could have arisen through natural selection. Instead, the existence of the VWFA provides evidence that specialized cortical regions may arise through experience alone. However, several recent papers (Vogel et al. 2012, 2014) have argued that the VWFA does not respond selectively to visually presented words, and others have argued on the basis of studies of neuropsychological patients for a “comingling of face and word mechanisms” in the brain (Behrmann & Plaut, 2014). Here, using individual-subjects analyses, we show that although there is a small amount of overlap between the left fusiform face area (FFA) and the VWFA in some subjects, the non-overlapping regions have sharply contrasting functional profiles (analyzed with left-out data), and the VWFA responds no more to faces than objects and no more to objects than to scrambled words (Figure 1). Further, diffusion tractography reveals clearly different connectivity fingerprints (Saygin et al. 2012) for the lFFA and VWFA. These findings underline the clear functional and anatomical distinction between the lFFA and VWFA. Of great interest for future studies will be how these regions arise in development.
Meeting abstract presented at VSS 2015