Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study

Wijayasiri, Pramudi; Hartley, Douglas E.H.; Wiggins, Ian M.

Abstract

The purpose of this study was to establish whether functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique based on optical principles, is suitable for studying the brain activity that underlies effortful listening. In an event-related fNIRS experiment, normally-hearing adults listened to sentences that were either clear or degraded (noise vocoded). These sentences were presented simultaneously with a non-speech distractor, and on each trial participants were instructed to attend either to the speech or to the distractor. The primary region of interest for the fNIRS measurements was the left inferior frontal gyrus (LIFG), a cortical region involved in higher-order language processing. The fNIRS results confirmed findings previously reported in the functional magnetic resonance imaging (fMRI) literature. Firstly, the LIFG exhibited an elevated response to degraded versus clear speech, but only when attention was directed towards the speech. This attention-dependent increase in frontal brain activation may be a neural marker for effortful listening. Secondly, during attentive listening to degraded speech, the haemodynamic response peaked significantly later in the LIFG than in superior temporal cortex, possibly reflecting the engagement of working memory to help reconstruct the meaning of degraded sentences. The homologous region in the right hemisphere may play an equivalent role to the LIFG in some left-handed individuals. In conclusion, fNIRS holds promise as a flexible tool to examine the neural signature of effortful listening.

Citation

Wijayasiri, P., Hartley, D. E., & Wiggins, I. M. (2017). Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study. Hearing Research, 351, 55-67. https://doi.org/10.1016/j.heares.2017.05.010

• Journal Article Type: Article
• Acceptance Date: May 23, 2017
• Online Publication Date: May 25, 2017
• Publication Date: 2017-08
• Deposit Date: Jun 28, 2017
• Publicly Available Date: Jun 28, 2017
• Journal: Hearing Research
• Print ISSN: 0378-5955
• Electronic ISSN: 1878-5891
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 351
• Pages: 55-67
• DOI: https://doi.org/10.1016/j.heares.2017.05.010
• Keywords: Functional near-infrared spectroscopy; fNIRS; Listening effort; Speech comprehension; Noise vocoding; Auditory cortex; Inferior frontal gyrus; Neuroimaging
• Public URL: https://nottingham-repository.worktribe.com/output/880761
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S0378595516306049
• Additional Information: This article is maintained by: Elsevier; Article Title: Brain activity underlying the recovery of meaning from degraded speech: A functional near-infrared spectroscopy (fNIRS) study; Journal Title: Hearing Research; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.heares.2017.05.010; Content Type: article; Copyright: © 2017 Elsevier B.V. All rights reserved.
• Contract Date: Jun 28, 2017