Neuroimaging meta-analyses of phonological awareness deficits in children with developmental dyslexia.

Theories of developmental dyslexia (DD) have emphasized deficits in phonological awareness (PA). This meta-analysis explored the neural underpinnings of PA deficits in children with DD including nine neuroimaging studies (154 children with DD; 202 typical readers; mean age range, 5.7–13.5 years; girls, 54%). Compared to typical readers, children with DD showed hypoactivity in the left inferior temporal/occipital gyri, which may reflect phonological processing inefficiencies. They also exhibited hyperactivity in the left precentral/postcentral gyri, right superior temporal gyrus, right insula, and right hippocampus, which could potentially represent as compensatory mechanisms for PA deficits. In contrast to higher level PA, children with DD may rely more on the hippocampus for processing larger sound units during lower-level PA tasks, though this interpretation remains to be further validated. With age, reliance on the cerebellum (lobule VI/Crus I) may decrease, possibly due to extensive reading and language training, yet this pattern requires further investigation. Sex differences suggested that girls with DD showed fewer PA deficits and might engage motor-based strategies. These interpretations should be considered provisional and emphasize the need for further empirical and meta-analytic investigations to delineate the specific functional roles of these brain regions in DD. Overall, this study may identify atypical activity patterns associated with PA deficits in children with DD.