The visual word form area is specialized for orthographic-semantic processing of written words

Poster Session E - Monday, April 15, 2024, 2:30 – 4:30 pm EDT, Sheraton Hall ABC

Naail Khan¹ (naailk90@gmail.com), Yara M. Iskandar¹, Alex Martin², W. Dale Stevens¹; ¹Department of Psychology and Centre for Vision Research, York University, Toronto, ²National Institute of Mental Health, National Institutes of Health, Bethesda, MD

The visual word form area (VWFA) is a region within the left occipitotemporal sulcus of literate humans, specialized for visual word recognition. However, its functional specificity is debated. Three competing hypotheses are that the VWFA is 1) a general visual processor, specialized for discriminating complex high-spatial-frequency stimuli – i.e., useful for reading but not specialized for words; 2) specialized at a sublexical level – i.e., sensitive to orthographic properties of words; 3) specialized for semantic processing of any meaningful visual stimuli, but not specialized for words. Conversely, we previously demonstrated that 1) the VWFA is specialized for lexical processing of written words, as it discriminates real words from pseudowords (non-word letter-strings orthographically matched to real words) and 2) the strength of intrinsic functional connectivity between VWFA and Wernicke’s area predicts reading skill. Thus, we hypothesize that the VWFA is specialized for orthographic-semantic processing – i.e., understanding the meaning of written words selectively. Adult participants (n=27) underwent 2 fMRI sessions: 1) A block-design multi-category functional localizer, to localize the VWFA and multiple category-selective control regions in each participant; 2) An event-related semantic classification task with words and images from multiple categories, to quantify category-discrimination in these regions. Representational similarity analysis demonstrated category-discrimination for words in VWFA, significantly more than images and all control regions. Multidimensional scaling and hierarchical clustering demonstrated superordinate-category-discrimination (living vs. non-living) for words in VWFA, significantly more than images and all control regions. Our results demonstrate that the VWFA is specialized for orthographic-semantic processing of written words selectively.

Topic Area: PERCEPTION & ACTION: Vision