Auditory–Motor Interaction Revealed by fMRI: Speech, Music, and Working Memory in Area Spt

Abstract

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.

Cortical interactions underlying the production of speech sounds

“…The activation peak was located in the posterior end of the left planum temporale (crosshairs in Fig. 4); this area has been implicated as an auditory-motor interface for speech (Buchsbaum, Hickok, & Humphries, 2001;Hickok, Buchsbaum, Humphries, & Muftuler, 2003).…”

Neural mechanisms underlying auditory feedback control of speech

“…Increased bilateral activation of posterior temporal regions during perturbation speech is consistent with previous results from studies of auditory feedback disruption, including delayed auditory feedback (Hirano et al, 1997;Hashimoto and Sakai, 2003), pitch perturbation (McGuire et al, 1996;Zarate and Zatorre, 2005;Fu et al, 2006) and noise masking (Christoffels et al, 2007) Numerous lines of evidence support the hypothesis that the expected consequences of articulation and resulting auditory feedback are compared in posterior temporal cortex (see Guenther et al, 2006 for detailed discussion). Portions of posterior left PT and lateral pSTg bilaterally have been shown to respond during both speech perception and speech production in several studies (Hickok et al, 2003;Buchsbaum et al, 2005). Bi-directional functional connections between inferior frontal and posterior temporal cortex have been demonstrated in vivo using cortico-cortical evoked potentials in humans (Matsumoto et al, 2004).…”

Dynamics of brain activity underlying working memory for music in a naturalistic condition

“…Using fMRI, Hickok, Buchsbaum and Humphries (2003) investigated verbal (nonsense sentences) and tonal (novel piano melodies) WM in non-musicians and observed the activation of Broca's area and left premotor regions in both conditions. These areas were also found in another experiment with non-musicians conducted by Koelsch et al (2009) employing sung syllables as stimuli, whereby either their pitch or syllable had to be remembered.…”