Parcellating the structure and function of the reading circuit

Abstract

Reading is a uniquely human skill, learned through extensive experience during childhood, with literacy becoming widespread only in the past few hundred years. Consequently, the neural circuitry underlying language could not have evolved to have circuitry genetically predefined for reading; this is unlike other expert skills such as face recognition, which can be seen in some of our evolutionary ancestors. Therefore, understanding the nature of the reading circuit strikes at the heart of the nature versus nurture debate about how expert skills shape, and are shaped by, brain circuitry. The PNAS article by Lerma-Usabiaga et al. (1) focuses on understanding the specialization of a particular brain territory, the left ventral occipitotemporal cortex (vOTC), known to be critical for visual word recognition. The study uses a combination of magnetic resonance imaging (MRI) and behavioral methods to carefully dissect two functionally and structurally distinct regions located within the vOTC that contribute to reading. Lerma-Usabiaga et al. (1) were motivated by previous studies that have used functional MRI to localize the “visual word form area” (VWFA). Conceptually, the VWFA is a brain region within the left vOTC that responds preferentially to printed words and word-like stimuli. This orthographic selectivity emerges with the acquisition of literacy, indicating that reading experience tunes this region for skilled reading (2). Indeed, individuals with poorer reading ability exhibit reduced selectivity in the vOTC (3), and damage in adulthood causes acquired alexia, in which printed words can no longer be recognized automatically (4). While researchers agree on these broad facts about the VWFA, they disagree on the precise location of the VWFA and its specific role in reading (4⇓–6). These disagreements could arise because different types of stimulus comparisons weight differentially for perceptual versus linguistic aspects of visual word recognition. Thus, like the proverbial men … [↵][1]1To whom correspondence should be addressed. Email: fiez{at}pitt.edu. [1]: #xref-corresp-1-1