Forebrain speech networks specifically impaired in children with listening difficulties

Children with neurodevelopmental disorders have a high rate of listening difficulty (LiD); impaired listening ability in the absence of hearing loss. However, the nature and mechanisms of LiD remain unclear. It has been proposed that LiD results from a primary auditory processing disorder, a perturbation of auditory specific brain activity underlying perception. An alternative hypothesis is that LiD results from a higher level, post-coding disorder of speech and language. This study used resting state fMRI of forebrain functional connectivity to distinguish between these hypotheses. It investigated the distribution of speech, non-speech 'sound', and visual processing networks in three groups of children aged 6-14 years with normal hearing. In addition to children with caregiver-identified LiD, two control groups were children diagnosed with attention-deficit/hyperactivity disorder (ADHD) and typically developing children. Relative to typically developing children, reduced functional connectivity of the speech network was found in children with LiD. No change was found in networks for non-speech sounds or visual stimuli in the children with LiD, suggesting a specific deficit in speech processing. Children with ADHD showed reduced connectivity in both speech and sound networks, but not in the visual network, suggesting a common underlying cause for auditory and speech difficulties. We conclude that listening difficulties in children are mediated by speech-specific neural mechanisms. The findings strengthen research calls for speech and language testing as a component of clinical pediatric audiological assessment.