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Poster E77, Friday, November 10, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Neural correlates of sine wave speech intelligibility in human frontal and temporal cortex

Matthew Leonard1, Sattar Khoshkhoo1, Nima Mesgarani2, Edward Chang1;1University of California, San Francisco, 2Columbia University

Auditory speech comprehension is the result of neural computations that occur in a broad network that includes the temporal lobe auditory cortex and the left inferior frontal cortex. It remains unclear how representations in this network differentially contribute to speech comprehension. Here, we recorded high-density direct cortical activity during a sine wave speech (SWS) listening task to examine detailed neural speech representations when the exact same acoustic input is comprehended versus not comprehended. Listeners heard SWS sentences (pre-exposure), followed by clear versions of the same sentences, which revealed the content of the sounds (exposure), and then the same SWS sentences again (post-exposure). Across all three task phases, high-gamma neural activity in the auditory cortex superior temporal gyrus was similar, distinguishing different words based on bottom-up acoustic features. In contrast, frontal regions were active only when the input was comprehended, which corresponded with stronger representational separability among spatiotemporal activity patterns evoked by different words. We observed this effect only in participants who were not able to comprehend the stimuli during the pre-exposure phase, indicating a direct relationship between frontal high-gamma activity and speech understanding. Together, these results demonstrate that both frontal and temporal cortical networks are involved in spoken language understanding, and that under certain listening conditions, frontal regions are involved in discriminating speech sounds.

Topic Area: Perception: Speech Perception and Audiovisual Integration

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