Pitch motor areas contribute to the perception of prosodic categories in speech

Abstract

Prosody is a fundamental aspect of speech characterized by suprasegmental features such as pitch. Prosodic pitch contours are used to convey speakers intentions, for example, to make a statement or ask a question. Understanding these intentions requires abstracting continuous, variable pitch information into discrete categories. Category perception has been proposed to recruit the motor system in an effector-specific manner, whereby cortical areas controlling motor effectors support speech sound recognition by identifying articulatory gestures. However, it remains unclear whether effectors involved in pitch production similarly contribute to prosodic category perception. To address this question, we collected magnetoencephalography data from 29 participants (15 females) while they first sang pitches arranged in five-tone melodies and then identified the prosody (Statement vs. Question) of single words varying in pitch contour along a five-level continuum. Using a region-restricted searchlight approach to decode singing from rest, we localized two premotor regions for pitch production, corresponding to the ventral and dorsal laryngeal motor cortex (LMC). A separate neural decoding analysis revealed that perceived prosodic categories were decodable in these regions, especially from the dorsal LMC that is more closely associated with pitch regulation. Importantly, decoding performance mirrored behavioral discriminability of prosodic categories across the continuum, suggesting that these regions are involved in perceptual decision-making. Finally, pitch motor areas exchanged category-related information with auditory regions, indicating these areas do not merely echo the processing in auditory regions. Together, these findings highlight effector-specific motor support for prosodic category perception, thereby broadening our understanding of motor involvement in speech perception. Significance StatementSpeech perception has been proposed to recruit the premotor cortex, with different subregions linking speech sounds to the articulatory gestures used to produce them. We investigated this idea through prosody--pitch changes in speech conveying meanings such as statements and questions. Using magnetoencephalography, we identified pitch motor areas during a singing task and tested whether they represent perceived prosodic categories. We found that prosodic categories were distinguishable in these regions and that this neural discriminability mirrored behavioral discriminability across clear and ambiguous prosody, suggesting involvement in perceptual decision-making. These findings are unlikely to reflect passive echoes from auditory regions, as pitch motor areas actively influenced them during categorical processing. Our results highlight effector-specific motor support for forming abstract prosodic representations.