| Temporal dynamics of sinusoidal and non-sinusoidal amplitude modulation. | |
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MedLine Citation:
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PMID: 21039961 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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Previous behavioural studies in human subjects have demonstrated the importance of amplitude modulations to the process of intelligible speech perception. In functional neuroimaging studies of amplitude modulation processing, the inherent assumption is that all sounds are decomposed into simple building blocks, i.e. sinusoidal modulations. The encoding of complex and dynamic stimuli is often modelled to be the linear addition of a number of sinusoidal modulations and so, by investigating the response of the cortex to sinusoidal modulation, an experimenter can probe the same mechanisms used to encode speech. The experiment described in this paper used magnetoencephalography to measure the auditory steady-state response produced by six sounds, all modulated in amplitude at the same frequency but which formed a continuum from sinusoidal to pulsatile modulation. Analysis of the evoked response shows that the magnitude of the envelope-following response is highly non-linear, with sinusoidal amplitude modulation producing the weakest steady-state response. Conversely, the phase of the steady-state response was related to the shape of the modulation waveform, with the sinusoidal amplitude modulation producing the shortest latency relative to the other stimuli. It is shown that a point in auditory cortex produces a strong envelope following response to all stimuli on the continuum, but the timing of this response is related to the shape of the modulation waveform. The results suggest that steady-state response characteristics are determined by features of the waveform outside of the modulation domain and that the use of purely sinusoidal amplitude modulations may be misleading, especially in the context of speech encoding. |
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Authors:
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Garreth Prendergast; Sam R Johnson; Gary G R Green |
Publication Detail:
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Type: Journal Article Date: 2010-10-08 |
Journal Detail:
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Title: The European journal of neuroscience Volume: 32 ISSN: 1460-9568 ISO Abbreviation: Eur. J. Neurosci. Publication Date: 2010 Nov |
Date Detail:
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Created Date: 2010-11-03 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8918110 Medline TA: Eur J Neurosci Country: France |
Other Details:
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Languages: eng Pagination: 1599-607 Citation Subset: IM |
Copyright Information:
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© 2010 The Authors. European Journal of Neuroscience © 2010 Federation of European Neuroscience Societies and Blackwell Publishing Ltd. |
Affiliation:
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York Neuroimaging Centre, University of York, The Biocentre, York Science Park, Heslington, York YO10 5DG, UK. Garreth.prendergast@ynic.york.ac.uk |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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