Zhang-Peng-2022

Word reading is critical for reading development. However, it has long been debated on the processes involved in real word and pseudoword decoding in developmental dyslexia (DD). We conducted a meta-analysis of 28 neuroimaging studies (519 participants with DD, 562 typical readers, age range 5–63 years, female 37.65%, 382 foci, 64 experimental contrasts) using effect-size signed differential mapping. Individuals with DD compared with typical readers showed hypoactivity in the left-lateralized reading network, including the occipitotemporal regions, temporoparietal regions, and inferior frontal gyri (pars triangularis and pars opercularis), in real word and pseudoword decoding. In pseudoword compared with real word decoding, hypoactivity was more severely reduced in the inferior frontal gyrus (pars opercularis). Metaregression showed that no hypoactivity was associated with age in real word decoding, whereas in pseudoword decoding, hypoactivity in the left superior temporal gyrus was negatively associated with age and hypoactivity in the left inferior temporal gyrus was quadratically associated with age. Accommodating the connectionist triangle model, our findings demonstrate that DD may be associated with abnormalities in both the direct orthography–phonology and the indirect orthography–semantics–phonology pathways across real word and pseudoword decoding. Compared with real word decoding, pseudoword decoding in those with DD may be more associated with abnormalities in the indirect pathway. With development, abnormalities in both pathways seem stable in real word decoding. In pseudoword decoding, abnormalities in the indirect pathway become more severe initially but could be improved in later development; abnormalities in the direct pathway could be persistently becoming more severe with age.