Visual Word Form Area demonstrates individual and task-agnostic consistency but inter-individual variability

Abstract

Ventral Occipital Temporal Cortex (VOTC) contains a mosaic of categorically-selective functional regions that respond to visual stimuli. Within left VOTC lies the Visual Word Form Area (VWFA) - a text-selective region that develops as individuals learn to read. While there is consistency in the general location of text-selective responses - within the posterior occipitotemporal sulcus (OTS) - there is substantial variability across individuals in the size and precise anatomical location. Moreover, debate continues regarding whether VWFA a) encodes the visual features of text, versus b) is driven by the task of reading. Using functional magnetic resonance imaging, we scanned adults and children as they completed two tasks while viewing text, pseudo fonts, faces, objects, limbs: (1) a fixation task where participants ignored stimuli while making psychophysical judgements on a fixation dot, and (2) a one-back task, where they attend to stimuli to detect repeats. We found a consistent VWFA location could be identified on each individuals cortical surface using either task. At the same time, the one-back task evoked a larger territory of text-selective response (leading to a larger ROI) than the fixation task. However, when averaged in template space, text-selective cortex could not be identified due to variability in the relative locations of text-, face-, object-, and limb-selective cortex. Thus, despite task-agnostic consistency in individual VWFA, text-selective responses are masked when averaged in template space due to variability in the exact configuration of category-selective regions. Furthermore, these effects were present in both children and adults.