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Subcortical Modulation of Speech Production Network.
Poster Session C, Friday, October 25, 4:30 - 6:00 pm, Great Hall 3 and 4
Anna Korzeniewska1, Noah Lu1, Alan Bush2,3, Nathan Crone1, Mark Richardson2,3; 1Johns Hopkins University, 2Massachusetts General Hospital, 3Harvard Medical School
Rationale: While the dynamics of cortical networks engaged in speech production have been well described, the role of subcortical regions remains under-explored. Using direct intracranial recordings, we investigated causal interactions between eloquent cortex and subthalamic nucleus (STN, known to modulate human behavior). Methods: High-density electrocorticographic recordings were made simultaneously with depth-recordings from STN in eight patients performing a syllable triplets repetition task during deep brain stimulation surgery (DBS). We used an event-related causality (ERC) method (Korzeniewska et al., 2022), based on the concept of Granger causality, to estimate the direction, intensity, and spectral content of direct propagation of neural activity during the task. For precise embedding of statistical significance in the time-frequency space, we used a newly developed bivariate smoothing model based on a two-dimensional moving average, which is optimal for reducing random noise while retaining a sharp step response. Results: Using our ERC approach, we recapitulated expected connectivity patterns at the cortical level. For example, we observed strong mutual causal interactions between auditory cortex (superior temporal gyrus, STG), Broca’s area (inferior frontal gyrus, IFG), and sensorimotor cortices (precentral and postcentral gyri) during both speech perception and speech production. Interestingly, we also observed strong mutual causal interactions between subthalamic nucleus (STN) and all the other investigated regions of the eloquent cortex, including Broca’s area and STG, during both speech perception and speech production. Remarkably, the strongest propagations of neural activity within the investigated subcortical-cortical network were observed during production of the last (third) syllable. Nevertheless, we also observed strong increases in neural propagation at the beginning of each syllable’s perception, and in the middle of each syllable’s perception. Conclusions: This study provides new empirical evidence that STN plays an important neurophysiological role in speech perception and production through mutual propagation of neural activity to and from eloquent cortex, including Broca’s and Wernicke’s areas. Korzeniewska A, Mitsuhashi T, Wang Y, Asano E, Franaszczuk PJ, Crone NE. Significance of event related causality (ERC) in eloquent neural networks. Neural Netw. 2022;149:204-216. Supported by: NINDS- U01NS117836 & NINDS-R01NS115929
Topic Areas: Language Production, Speech Motor Control