Demystifying visual word form area visual and nonvisual response properties with precision fMRI.

The visual word form area (VWFA) is a region in the left ventrotemporal cortex (VTC) whose specificity remains contentious. Using precision fMRI, we examine the VWFA's responses to numerous visual and nonvisual stimuli, comparing them to adjacent category-selective visual regions and regions involved in language and attentional demand. We find that VWFA responds moderately to non-word visual stimuli, but is unique within VTC in its pronounced selectivity for visual words. Interestingly, the VWFA is also the only category-selective visual region engaged in auditory language, unlike the ubiquitous attentional demand effect throughout the VTC. However, this language selectivity is dwarfed by its visual responses even to nonpreferred categories, indicating the VWFA is not a core (amodal) language region. We also observed two additional auditory language VTC clusters, but these had no specificity for visual words. Our detailed investigation clarifies longstanding controversies about the landscape of visual and auditory language functionality within VTC.