Authors: Karen Emmorey, Jill Weisberg, Stephen McCullough, Jennifer A F Petrich.
Publication: Brain and Language (Elsevier). Volume 126, Issue 2, Pages 169-180 2013 | DOI: 10.1016/j.bandl.2013.05.001
- • fMRI study of the neural circuits engaged in skilled adult deaf and hearing readers.
- • Semantic word processing engaged a left frontal–temporal circuit in both groups.
- • Parietal activity was increased in deaf vs. hearing readers for a phonological task.
- • Left precentral gyrus was more active in deaf vs. hearing for the phonological task.
- • Segregation of semantics and phonology in LIPC was more robust for deaf readers.
We examined word-level reading circuits in skilled deaf readers whose primary language is American Sign Language, and hearing readers matched for reading ability (college level). During fMRI scanning, participants performed a semantic decision (concrete concept?), a phonological decision (two syllables?), and a false-font control task (string underlined?). The groups performed equally well on the semantic task, but hearing readers performed better on the phonological task. Semantic processing engaged similar left frontotemporal language circuits in deaf and hearing readers. However, phonological processing elicited increased neural activity in deaf, relative to hearing readers, in the left precentral gyrus, suggesting greater reliance on articulatory phonological codes, and in bilateral parietal cortex, suggesting increased phonological processing effort. Deaf readers also showed stronger anterior–posterior functional segregation between semantic and phonological processes in left inferior prefrontal cortex. Finally, weaker phonological decoding ability did not alter activation in the visual word form area for deaf readers.
Emmorey, K., Weisberg, J., McCullough, S., & Petrich, J. A. (2013). Mapping the reading circuitry for skilled deaf readers: an fMRI study of semantic and phonological processing. Brain and language, 126(2), 169–180. https://doi.org/10.1016/j.bandl.2013.05.001
Increased parietal activation for deaf readers (vs. hearing) contrasts with reduced activation found in dyslexic hearing readers(vs. typical readers) for whom phonological decisions are also more difﬁcult (e.g., Hoeft et al., 2006). Thus, although both deaf and dyslexic readers have limited phonemic awareness skills (e.g., Bruck,1992; Miller, 1997), they appear to exhibit contrasting neural response patterns in parietal cortex (although a study with dyslexic readers performing the syllable judgment task is needed).