Does Semantic Context Benefit Speech Understanding through "Top-Down" Processes? Evidence from Time-resolved Sparse fMRI.

Détails

ID Serval
serval:BIB_096D7C31ADA7
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Institution
Titre
Does Semantic Context Benefit Speech Understanding through "Top-Down" Processes? Evidence from Time-resolved Sparse fMRI.
Périodique
Journal of Cognitive Neuroscience
Auteur(s)
Davis M.H., Ford M.A., Kherif F., Johnsrude I.S.
ISSN
1530-8898 (Electronic)
ISSN-L
0898-929X
Statut éditorial
Publié
Date de publication
2011
Volume
23
Numéro
12
Pages
3914-3932
Langue
anglais
Notes
Publication types: Journal ArticlePublication Status: ppublish
Résumé
When speech is degraded, word report is higher for semantically coherent sentences (e.g., her new skirt was made of denim) than for anomalous sentences (e.g., her good slope was done in carrot). Such increased intelligibility is often described as resulting from "top-down" processes, reflecting an assumption that higher-level (semantic) neural processes support lower-level (perceptual) mechanisms. We used time-resolved sparse fMRI to test for top-down neural mechanisms, measuring activity while participants heard coherent and anomalous sentences presented in speech envelope/spectrum noise at varying signal-to-noise ratios (SNR). The timing of BOLD responses to more intelligible speech provides evidence of hierarchical organization, with earlier responses in peri-auditory regions of the posterior superior temporal gyrus than in more distant temporal and frontal regions. Despite Sentence content × SNR interactions in the superior temporal gyrus, prefrontal regions respond after auditory/perceptual regions. Although we cannot rule out top-down effects, this pattern is more compatible with a purely feedforward or bottom-up account, in which the results of lower-level perceptual processing are passed to inferior frontal regions. Behavioral and neural evidence that sentence content influences perception of degraded speech does not necessarily imply "top-down" neural processes.
Pubmed
Web of science
Création de la notice
08/12/2011 12:11
Dernière modification de la notice
20/08/2019 12:31
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