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Enhanced early-latency electromagnetic activity in the left premotor cortex is associated with successful phonetic categorization.
MedLine Citation:
PMID:  22361165     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Sensory-motor interactions between auditory and articulatory representations in the dorsal auditory processing stream are suggested to contribute to speech perception, especially when bottom-up information alone is insufficient for purely auditory perceptual mechanisms to succeed. Here, we hypothesized that the dorsal stream responds more vigorously to auditory syllables when one is engaged in a phonetic identification/repetition task subsequent to perception compared to passive listening, and that this effect is further augmented when the syllables are embedded in noise. To this end, we recorded magnetoencephalography while twenty subjects listened to speech syllables, with and without noise masking, in four conditions: passive perception; overt repetition; covert repetition; and overt imitation. Compared to passive listening, left-hemispheric N100m equivalent current dipole responses were amplified and shifted posteriorly when perception was followed by covert repetition task. Cortically constrained minimum-norm estimates showed amplified left supramarginal and angylar gyri responses in the covert repetition condition at ~100ms from stimulus onset. Longer-latency responses at ~200ms were amplified in the covert repetition condition in the left angular gyrus and in all three active conditions in the left premotor cortex, with further enhancements when the syllables were embedded in noise. Phonetic categorization accuracy and magnitude of voice pitch change between overt repetition and imitation conditions correlated with left premotor cortex responses at ~100 and ~200ms, respectively. Together, these results suggest that the dorsal stream involvement in speech perception is dependent on perceptual task demands and that phonetic categorization performance is influenced by the left premotor cortex.
Authors:
Jussi Alho; Marc Sato; Mikko Sams; Jean-Luc Schwartz; Hannu Tiitinen; Iiro P Jääskeläinen
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-2-14
Journal Detail:
Title:  NeuroImage     Volume:  -     ISSN:  1095-9572     ISO Abbreviation:  -     Publication Date:  2012 Feb 
Date Detail:
Created Date:  2012-2-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9215515     Medline TA:  Neuroimage     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012. Published by Elsevier Inc.
Affiliation:
Brain and Mind Laboratory, Department of Biomedical Engineering and Computational Science, Aalto University, School of Science, P.O. Box 12200, FIN-00076 AALTO, Finland.
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