| The analysis of simple and complex auditory signals in human auditory cortex: magnetoencephalographic evidence from M100 modulation. | |
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MedLine Citation:
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PMID: 20445455 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: Ecologically valid signals (e.g., vowels) have multiple components of substantially different frequencies and amplitudes that may not be equally cortically represented. In this study, we investigate a relatively simple signal at an intermediate level of complexity, two-frequency composite tones, a stimulus lying between simple sinusoids and ecologically valid signals such as speech. We aim to characterize the cortical response properties to better understand how complex signals may be represented in auditory cortex. DESIGN: Using magnetoencephalography, we assessed the sensitivity of the M100/N100m auditory-evoked component to manipulations of the power ratio of the individual frequency components of the two-frequency complexes. Fourteen right-handed subjects with normal hearing were scanned while passively listening to 10 complex and 12 simple signals. The complex signals were composed of one higher frequency and one lower frequency sinusoid; the lower frequency sinusoidal component was at one of the five loudness levels relative to the higher frequency one: -20, -10, 0, +10, +20 dB. The simple signals comprised all the complex signal components presented in isolation. RESULTS: The data replicate and extend several previous findings: (1) the systematic dependence of the M100 latency on signal intensity and (2) the dependence of the M100 latency on signal frequency, with lower frequency signals ( approximately 100 Hz) exhibiting longer latencies than higher frequency signals ( approximately 1000 Hz) even at matched loudness levels. (3) Importantly, we observe that, relative to simple signals, complex signals show increased response amplitude-as one might predict-but decreased M100 latencies. CONCLUSION: : The data suggest that by the time the M100 is generated in auditory cortex ( approximately 70 to 80 msecs after stimulus onset), integrative processing across frequency channels has taken place which is observable in the M100 modulation. In light of these data models that attribute more time and processing resources to a complex stimulus merit reevaluation, in that our data show that acoustically more complex signals are associated with robust temporal facilitation, across frequencies and signal amplitude level. |
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Authors:
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Julian Jenkins; William J Idsardi; David Poeppel |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural |
Journal Detail:
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Title: Ear and hearing Volume: 31 ISSN: 1538-4667 ISO Abbreviation: Ear Hear Publication Date: 2010 Aug |
Date Detail:
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Created Date: 2010-07-02 Completed Date: 2010-10-07 Revised Date: 2011-08-01 |
Medline Journal Info:
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Nlm Unique ID: 8005585 Medline TA: Ear Hear Country: United States |
Other Details:
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Languages: eng Pagination: 515-26 Citation Subset: IM |
Affiliation:
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Department of Biology, University of Maryland, College Park, Maryland 20742, USA. julianj@umd.edu |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acoustic Stimulation
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methods Adult Analysis of Variance Auditory Cortex / physiology Auditory Threshold Female Hearing / physiology* Humans Loudness Perception Magnetoencephalography* Male Reaction Time Young Adult |
| Grant Support | |
ID/Acronym/Agency:
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2R01DC05660/DC/NIDCD NIH HHS; DC-00046/DC/NIDCD NIH HHS; R01 DC005660-08/DC/NIDCD NIH HHS; R01 DC005660-09/DC/NIDCD NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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