Temporal organization of "internal speech" as a basis for cerebellar modulation of cognitive functions.
The sequencing of smooth and rhythmically "sculptured" words and phrases at a speaker's habitual speech rate (4 Hz to 6 Hz) critically depends on the cerebellum. Besides overt performance, the cerebellum also seems to organize the syllabic structure of "auditory verbal imagery" or "internal speech"--that is, a prearticulatory but otherwise fully elaborated and temporally organized representation of verbal utterances. As a consequence, cerebellar disorders may compromise cognitive operations that involve a speech code, such as verbal working memory, or disrupt cognitive processes that encompass linguistic mediation. Besides the temporal organization of syllable strings at a prearticulatory level, cerebellar patients are impaired in speech perception tasks requiring the encoding of durational parameters of the acoustic signal. The hemodynamic responses associated with these two aspects of verbal-acoustic communication--internal speech and speech perception--were found to be organized along the rostro-caudal direction within paravermal aspects of the superior right cerebellar hemisphere. Those areas of the right cerebellar hemisphere thus might provide a common platform for the computation of temporal aspects of verbal utterances in the domains of both speech production and perception.
Ackermann
Hermann
H
University of Tuebingen.
Mathiak
Klaus
K
Ivry
Richard B
RB
D001921:Brain / Q000098:blood supply; D002531:Cerebellum / Q000098:blood supply / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D007839:Functional Laterality / Q000502:physiology; D005868:Gestures; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D013060:Speech; D013067:Speech Perception / Q000502:physiology; D013850:Thinking; D013997:Time Factors; D014705:Verbal Behavior / Q000502:physiology