Aberrant modulation of broadband neural oscillations reflects vocal sensorimotor deficits in post-stroke aphasia.

OBJECTIVE: The present study investigated the neural oscillatory correlates of impaired vocal sensorimotor control in left-hemisphere stroke.

METHODS: Electroencephalography (EEG) signals were recorded from 34 stroke and 46 control subjects during speech vowel vocalization and listening tasks under normal and pitch-shifted auditory feedback.

RESULTS: Time-frequency analyses revealed aberrantly decreased theta (4-8 Hz) and increased gamma band (30-80 Hz) power in frontal and posterior parieto-occipital regions as well as reduced alpha (8-13 Hz) and beta (13-30 Hz) desynchronization over sensorimotor areas before speech vowel vocalization in left-hemisphere stroke compared with controls. Subjects with the stroke also presented with aberrant modulation of broadband (4-80 Hz) neural oscillations over sensorimotor regions after speech vowel onset during vocalization and listening under normal and altered auditory feedback. We found that the atypical pattern of broadband neural oscillatory modulation was correlated with diminished vocal feedback error compensation behavior and the severity of co-existing language-related aphasia symptoms associated with left-hemisphere stroke.

CONCLUSIONS: These findings indicate complex interplays between the underlying mechanisms of speech and language and their deficits in post-stroke aphasia.

SIGNIFICANCE: Our data motivate the notion of studying neural oscillatory dynamics as a critical component for the examination of speech and language disorders in post-stroke aphasia.