Reading and Subcortical Auditory Function

Although it is largely agreed that phonological processing deficits are a major cause of poor reading, the neural origins of phonological processing are not well understood. We now show, for the first time, that phonological decoding, measured with a test of single-nonword reading, is significantly correlated with the timing of subcortical auditory processing and also, to a lesser extent, with the robustness of subcortical representation of the harmonic content of speech, but not with pitch encoding. The relationships we observe between reading and subcortical processing fall along a continuum, with poor readers at one end and good readers at the other. These data suggest that reading skill may depend on the integrity of subcortical auditory mechanisms and are consistent with the idea that subcortical representation of the acoustic features of speech may play a role in normal reading as well as in the development of reading disorders. These data establish a significant link between subcortical auditory function and reading, thereby contributing to the understanding of the biological bases of reading. At a more general level, these findings are among the first to establish a direct relationship between subcortical sensory function and a specific cognitive skill (reading). We argue that this relationship between cortical and subcortical function could be shaped during development by the corticofugal pathway and that this cortical-subcortical link could contribute to the phonological processing deficits experienced by poor readers.