Abstract
The ventral temporal cortex (VTC) houses multiple high-level category-selective regions (e.g., faces, objects, scenes). The visual word form area (VWFA) is a particularly unique example of a high-level visual area that is experience-dependent, exhibiting robust responses to orthography only in literate individuals. The VWFA is usually found in a stereotyped location within the left VTC across cultures and languages and disruption of the VWFA leads to failures in word recognition. However, it remains unclear how the word-selectivity and laterality of the VWFA change to accommodate gains in typical reading development. Does increasing word-selectivity account for individual differences in different aspects of normal reading? When does the laterality of word-selectivity emerge? We explored these questions by recording fMRI activation to visual Words, Scrambled Words, line-drawings of Objects, and Faces in adults (N=25) and children (N=29, age 4-12 years). We found that like adults, beginning readers (6-12 years) already showed significantly higher activation to Words compared to other categories, and importantly, word-selectivity in the lVWFA displayed no significant differences between motion-matched adults and beginning readers. This result suggests that the gains in reading comprehension with increased education cannot be attributed to category level word-selectivity. In contrast, a comparison of lVWFA word-selectivity in pre-readers vs. beginning readers confirmed that word-selectivity was observed only after literacy and plateaued at age 6. Further, left laterality emerged once a child started to read and beginning readers already showed adult-like laterality. Finally, we found that the word-selectivity of the VWFA in children was correlated with individual differences in specific (and only visual, not phonemic or linguistic) aspects of reading. Altogether, we show that word-selectivity emerges at the onset of reading, is left-lateralized, and is already variable across individuals, reflecting finer-grained individual differences in the visual aspects of reading/pre-reading ability.