Document Detail

Semantic and acoustic analysis of speech by functional networks with distinct time scales.
MedLine Citation:
PMID:  20580635     Owner:  NLM     Status:  MEDLINE    
Speech perception requires the successful interpretation of both phonetic and syllabic information in the auditory signal. It has been suggested by Poeppel (2003) that phonetic processing requires an optimal time scale of 25 ms while the time scale of syllabic processing is much slower (150-250 ms). To better understand the operation of brain networks at these characteristic time scales during speech perception, we studied the spatial and dynamic properties of EEG responses to five different stimuli: (1) amplitude modulated (AM) speech, (2) AM speech with added broadband noise, (3) AM reversed speech, (4) AM broadband noise, and (5) AM pure tone. Amplitude modulation at gamma band frequencies (40 Hz) elicited steady-state auditory evoked responses (SSAERs) bilaterally over primary auditory cortices. Reduced SSAERs were observed over the left auditory cortex only for stimuli containing speech. In addition, we found over the left hemisphere, anterior to primary auditory cortex, a network whose instantaneous frequencies in the theta to alpha band (4-16 Hz) are correlated with the amplitude envelope of the speech signal. This correlation was not observed for reversed speech. The presence of speech in the sound input activates a 4-16 Hz envelope tracking network and suppresses the 40-Hz gamma band network which generates the steady-state responses over the left auditory cortex. We believe these findings to be consistent with the idea that processing of the speech signals involves preferentially processing at syllabic time scales rather than phonetic time scales.
Siyi Deng; Ramesh Srinivasan
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, U.S. Gov't, Non-P.H.S.     Date:  2010-05-16
Journal Detail:
Title:  Brain research     Volume:  1346     ISSN:  1872-6240     ISO Abbreviation:  Brain Res.     Publication Date:  2010 Jul 
Date Detail:
Created Date:  2010-07-13     Completed Date:  2010-10-19     Revised Date:  2014-05-22    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  Netherlands    
Other Details:
Languages:  eng     Pagination:  132-44     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Elsevier B.V. All rights reserved.
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MeSH Terms
Acoustic Stimulation
Auditory Cortex / physiology
Auditory Perception / physiology*
Functional Laterality / physiology
Nerve Net / physiology*
Signal Processing, Computer-Assisted
Speech Perception / physiology*
Young Adult
Grant Support

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