Speech and song: the role of the cerebellum

An exploration into cerebellar activity during the perception and production of speech and song may elucidate general underlying cerebellar functions. Recently, the cerebellum has been hypothesized to be involved with sharpening sensory input, temporal coordination and processing of motor articulation and perception, as well as instantiation of internal models that simulate the input-output characteristics of a specific system. Sung language and spoken language share many common features (physiology for articulation and perception as well as phonology, phonotactics, syntax, and semantics of the underlying language), although they differ in certain vocal and prosodic aspects. A review of the literature on perception and production of singing and speech reveals considerable overlap in the lateral aspect of the VI lobule of the posterior cerebellum, a region known to somatotopically represent the lips and tongue. This region may instantiate internal models of vocal tract articulation that simulate well learned phonological and/or segmental articulatory - auditory/orosensory mappings utilized for both speech and singing. Recent results show tendencies for left cerebellar hemispheric specialization for processing of singing and right specialization for processing of speech, both in the VI lobule of the cerebellum, inferior to that found for representing both speech and singing. Given the crossed pattern of cerebellar-cortical anatomical connectivity the findings are consistent with the hypothesis that the right cerebellum differentially processes high pass filtered information (segmental properties) and the left cerebellum differentially processes low pass filtered information (prosodic, melodic properties). Further research is necessary to examine these hypotheses and their alternatives directly.