Common neural responses to narrative speech indisorders of consciousness

ObjectiveClinical assessment of auditory attention in patients with disorders of consciousness is often limited by motor impairment. Here, we employ inter-subject correlations among electroencephalography responses to naturalistic speech in order to assay auditory attention among patients and healthy controls.\n\nMethodsElectroencephalographic data were recorded from 20 subjects with disorders of consciousness and 14 healthy controls during of two narrative audio stimuli, presented both forwards and time-reversed. Inter-subject correlation of evoked electroencephalography signals were calculated, comparing responses of both groups to those of the healthy control subjects. This analysis was performed blinded and subsequently compared to the diagnostic status of each patient based on the Coma Recovery Scale-Revised.\n\nResultsSubjects with disorders of consciousness exhibit significantly lower inter-subject correlation than healthy controls during narrative speech. Additionally, while healthy subjects had higher inter-subject correlation values in forward vs. backwards presentation, neural responses did not vary significantly with the direction of playback in subjects with disorders of consciousness. Increased inter-subject correlation values in the backward speech condition were noted with improving disorder of consciousness diagnosis, both in cross-sectional analysis and in a subset of patients with longitudinal data.\n\nInterpretationInter-subject correlation of neural responses to narrative speech audition differentiates healthy controls from patients and appears to index clinical diagnoses in disorders of consciousness.