Position coding in the visual word form area

Abstract

How does our brain achieve its impressive expertise to effortlessly read written words? It has been proposed that a key element of the capability to recognize visually presented words (as well as other objects) is a normalization process that is assumed to operate along the visual hierarchy. This normalization process would remove varying aspects of presented words from the evoked retinal representations in the eye and early visual cortex, including spatial position, size, and rotation, resulting in standardized (invariant) representations in higher-level visual areas (Fig. 1 A and B). Numerous studies (1⇓⇓⇓–5) have identified a region in a small strip of the fusiform gyrus in the left hemisphere that seems to be specialized for orthographic processing of words called the visual word form area (VWFA). Because this area is at a rather high level within the visual hierarchy and in close proximity to areas specialized for object recognition (e.g., faces), dominant reading theories assume that the representations within the VWFA contain invariant representations of words (5). The study by Rauschecker et al. in PNAS (6) challenges this traditional view, showing, with a series of elegant experiments, that the representations in VWFA are actually position-dependent (i.e., they reflect the original position of words at the retina) (Fig. 1 C and D), despite the rather high-level location of this area in the visual hierarchy.