Dual routes for verbal repetition: articulation-based and acoustic-phonetic codes for pseudoword and word repetition, respectively.
Speech production is inextricably linked to speech perception, yet they are usually investigated in isolation. In this study, we employed a verbal-repetition task to identify the neural substrates of speech processing with two ends active simultaneously using functional MRI. Subjects verbally repeated auditory stimuli containing an ambiguous vowel sound that could be perceived as either a word or a pseudoword depending on the interpretation of the vowel. We found verbal repetition commonly activated the audition-articulation interface bilaterally at Sylvian fissures and superior temporal sulci. Contrasting word-versus-pseudoword trials revealed neural activities unique to word repetition in the left posterior middle temporal areas and activities unique to pseudoword repetition in the left inferior frontal gyrus. These findings imply that the tasks are carried out using different speech codes: an articulation-based code of pseudowords and an acoustic-phonetic code of words. It also supports the dual-stream model and imitative learning of vocabulary.
Interdisciplinary Program in Cognitive Science, Seoul National University, Republic of Korea.
Sejin
S
Yoo
Jun-Young
JY
Chung
Hyeon-Ae
HA
Jeon
Kyoung-Min
KM
Lee
Young-Bo
YB
Kim
Zang-Hee
ZH
Cho
D000161:Acoustic Stimulation; D000293:Adolescent; D000328:Adult; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007100:Imitative Behavior / Q000502:physiology*; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D013060:Speech / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*