Neural representations of speech production in neocortical and cerebellar regions

Speech production depends on the precise temporal integration of articulatory movements with phonation. While ventral primary motor cortex is known to encode articulatory features, how phonatory timing, and its coordination with articulation, is represented across cortical and cerebellar circuits remains poorly understood. Using 7T functional MRI, we examined neural representations during overt syllable production varying in place of articulation and voice onset time. Multivariate analyses revealed reliable, syllable-specific differences in activity patterns across both cortical and cerebellar speech regions. Ventral primary sensorimotor cortex distinguished syllables by place of articulation, whereas dorsal sensorimotor cortex was more sensitive to the timing of voice onset relative to articulation. Secondary sensorimotor speech areas, including the operculum and auditory cortex, showed a hybrid representational profile, integrating both articulatory and phonatory features. In the cerebellum, representational geometry was dominated by the place of articulation; however, overall syllable representations were most similar to those in the operculum, accounting for unique variance beyond that explained by ventral sensorimotor cortex. Together, these findings reveal feature-specific representational tuning across primary sensorimotor regions during speech production. The selective representational alignment between operculum and cerebellum may support the refinement of speech motor plans prior to execution.