Demystifying the Visual Word Form Area: Visual and Nonvisual Response Properties of Ventral Temporal Cortex with precision fMRI

Summary The functional nature of the visual word form area (VWFA), a region in left ventrotemporal cortex (VTC), remains debated after over two decades of investigation. Here we use precision fMRI to comprehensively examine the VWFA’s responses to numerous visual and nonvisual stimuli. We find that the VWFA is a distinct region that while showing moderate activation to non-word visual stimuli, its response to words towers above other conditions. Interestingly, the VWFA is also the only VTC region uniquely engaged in auditory language processing, in contrast with the ubiquitous attentional effect within the VTC. However, this language selectivity is dwarfed by its visual responses. This suggests the VWFA primarily functions as a visual look-up orthographic dictionary. Searching within the entire VTC further reveals an additional language cluster in anterior fusiform preferring general visual semantics. Our detailed examination of the VWFA in direct comparison to other VTC regions clarifies the long-standing controversies about its functionality.