Understanding Neural Signals related to Speech Processing in Humans During Sleep
Abstract
Many cognitive processes are surprisingly preserved during sleep, including the processing of basic language stimuli. However, whether the sleeping brain can process complex, natural speech is not yet known. The present study used regularized linear regression to understand which features of narrative speech, ranging from low-level acoustic information to higher-level linguistic information, are processed during sleep. Participants were exposed to an intact and scrambled narrative story while they were napping or lying awake. Temporal response functions (TRFs) mapped the relationship between participants’ EEG neural responses and the (1) auditory envelope, (2) word onsets and (3) semantic dissimilarity of words. For all three analyses, delayed but statistically similar TRF components were observed during sleep and wake. These findings suggest that the sleeping brain is capable of low-level auditory processing, speech segmentation and semantic processing of narrative speech. These findings highlight that natural language processing remains remarkably intact during sleep.