Auditory-motor interaction revealed by fMRI: speech, music, and working memory in area Spt.
The concept of auditory-motor interaction pervades speech science research, yet the cortical systems supporting this interface have not been elucidated. Drawing on experimental designs used in recent work in sensory-motor integration in the cortical visual system, we used fMRI in an effort to identify human auditory regions with both sensory and motor response properties, analogous to single-unit responses in known visuomotor integration areas. The sensory phase of the task involved listening to speech (nonsense sentences) or music (novel piano melodies); the "motor" phase of the task involved covert rehearsal/humming of the auditory stimuli. A small set of areas in the superior temporal and temporal-parietal cortex responded both during the listening phase and the rehearsal/humming phase. A left lateralized region in the posterior Sylvian fissure at the parietal-temporal boundary, area Spt, showed particularly robust responses to both phases of the task. Frontal areas also showed combined auditory + rehearsal responsivity consistent with the claim that the posterior activations are part of a larger auditory-motor integration circuit. We hypothesize that this circuit plays an important role in speech development as part of the network that enables acoustic-phonetic input to guide the acquisition of language-specific articulatory-phonetic gestures; this circuit may play a role in analogous musical abilities. In the adult, this system continues to support aspects of speech production, and, we suggest, supports verbal working memory.
Hickok
Gregory
G
University of California, Irvine, CA 92697, USA. gshickok@uci.edu
Buchsbaum
Bradley
B
Humphries
Colin
C
Muftuler
Tugan
T
D000161:Acoustic Stimulation; D001307:Auditory Perception / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D009043:Motor Activity / Q000502:physiology*; D009146:Music; D010897:Pitch Discrimination; D011214:Practice, Psychological; D013060:Speech / Q000502:physiology*; D013997:Time Factors