Poster A7, Thursday, August 16, 10:15 am – 12:00 pm, Room 2000AB
Intracranial Neurophysiology of Auditory Feedback Control During Speech Production
Muge Ozker Sertel1, Margaret A McAlister1, Patricia Dugan1, Daniel Friedman1, Werner Doyle2, Orrin Devinsky1, Adeen Flinker1;1Department of Neurology, New York University School of Medicine, 2Department of Neurosurgery, New York University School of Medicine
Accurate and fluent production of speech critically depends on hearing one’s self. The auditory system continuously monitors self-generated vocal sounds to detect vocalization errors, which allows for the online adjustment of motor actions to achieve intended vocalization. When auditory feedback is disrupted, vocalization is altered to compensate for the disruption (e.g. speaking loudly when listening to music over headphones). To study auditory feedback control during speech production, we used a delayed auditory feedback (DAF) paradigm, which strongly disrupts speech fluency by causing stutter-like speech, characterized by syllable repetitions, prolonged words and longer pauses. While delaying speech in real time is a common therapeutic approach in stutterers, where it interestingly improves speech fluency, the underlying neural mechanism remains understudied and poorly understood. Here, we employed rare neurosurgical electrocorticography (ECoG) recordings directly from cortex. Subjects were visually presented with 3-syllable words and 8-word sentences in separate sessions. As they read aloud the presented stimuli, their voice was recorded by a microphone and played back to them with 0, 50,100 or 200 millisecond delays through earphones. Behaviorally, articulation duration increased significantly with increasing amount of delays for both word reading (For 0, 50, 100 and 200 ms delay: 0.72, 0.75, 0.78, 0.81; F = 38.4, p = 10-9) and sentence reading (2.77, 3, 3.49, 3.82; F = 111, p = 10-16). Neural responses in the high-gamma broadband frequencies (70-150 Hz) were used as the primary measure of neural activity. Auditory electrodes over the superior temporal gyrus showed increased neural responses as delays increased both for word reading (F = 98, p = 10-16) and for sentence reading (F = 123, p = 10-16). Motor electrodes showed increased neural responses for increasing delays only for sentence reading (F = 37, p = 10-9) but not for word reading (F = 3.6, p = 0.06). This represents one of the first reports of delayed auditory feedback in human electrophysiology. The data suggests that while auditory cortex encodes mismatches between intended and produced speech, motor cortex is preferentially engaged only when articulation demand increases during production of longer, more complex speech segments.
Topic Area: Speech Motor Control and Sensorimotor Integration