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Auditory hemispheric lateralization for speech and melody: from cortex to subcortex

Poster Session C - Sunday, March 8, 2026, 5:00 – 7:00 pm PDT, Fairview/Kitsilano Ballrooms

Jérémie Ginzburg^1,2 (jeremie.ginzburg@mcgill.ca), Alberto Ara^1,3, Juliana Gelber¹, Philippe Albouy², Robert J Zatorre¹; ¹Montreal Neurological Institute, McGill University, Montreal, Canada, ²CERVO research center, Laval University, Québec, Canada, ³Department of Basic and Clinical Psychology and Psychobiology, Basic Psychology area, Universitat Jaume

Hemispheric lateralization is a fundamental feature of human brain organization, yet existing models are almost exclusively derived from cortical data, leaving subcortical contributions largely unexplored. This gap reflects limitations in spatial resolution of conventional neuroimaging, that can now be overcome with ultra–high field 7-Tesla magnetic resonance imaging (7T-fMRI). Building on recent evidence that cortical auditory asymmetries arise from differential sensitivity to spectrotemporal modulations in natural sounds, this study investigates whether such lateralization already emerges at subcortical stages of auditory processing. Using 7T-FMRI, twenty-three healthy adults listened to auditory stimuli while BOLD signals were acquired at 1.4 mm³ isotropic resolution. The imaging field of view included bilateral auditory cortices as well as medial geniculate bodies and inferior colliculi. Participants heard 125 previously validated stimuli comprising speech-only, vocalized melody-only, and song excerpts containing both speech and melody. Item-identity decoding using searchlight classification successfully replicated well-established cortical asymmetries, with stronger left-hemispheric representations for speech and right-hemispheric representations for music. Crucially, preliminary analyses indicate reliable event-locked BOLD responses in subcortical nuclei, opening the door to testing lateralized encoding in these subcortical areas. Ongoing work focuses on modeling structure-specific neurovascular dynamics in subcortical regions to enable multivariate decoding analyses comparable to those performed in the cortex. Subcortical functional asymmetries would indicate that lateralized spectrotemporal tuning is established early in the auditory hierarchy, whereas their absence would suggest that spectrotemporal tuning differences arise primarily at the cortical level through selective weighting of subcortical inputs.

Topic Area: PERCEPTION & ACTION: Audition