Transformation of a temporal speech cue to a spatial neural code in human auditory cortex
- University of California, San Francisco, United States
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Netherlands
Abstract
In speech, listeners extract continuously-varying spectrotemporal cues from the acoustic signal to perceive discrete phonetic categories. Spectral cues are spatially encoded in the amplitude of responses in phonetically-tuned neural populations in auditory cortex. It remains unknown whether similar neurophysiological mechanisms encode temporal cues like voice-onset time (VOT), which distinguishes sounds like /b/-/p/. We used direct brain recordings in humans to investigate the neural encoding of temporal speech cues with a VOT continuum from /ba/ to /pa/. We found that distinct neural populations respond preferentially to VOTs from one phonetic category, and are also sensitive to sub-phonetic VOT differences within a population's preferred category. In a simple neural network model, simulated populations tuned to detect either temporal gaps or coincidences between spectral cues captured encoding patterns observed in real neural data. These results demonstrate that a spatial/amplitude neural code underlies the cortical representation of both spectral and temporal speech cues.
Data availability
Data and code are available under a Creative Commons License at the project page on Open Science Framework (https://osf.io/9y7uh/).
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Transformation of a temporal speech cue to a spatial neural code in human auditory cortexOPen Science Framework, 9y7uh/.
Article and author information
Author details
Funding
National Institutes of Health (R01-DC012379)
- Edward F Chang
National Institutes of Health (F32-DC015966)
- Neal P Fox
European Commission (FP7-623072)
- Matthias J Sjerps
New York Stem Cell Foundation
- Edward F Chang
William K. Bowes, Jr. Foundation
- Edward F Chang
Howard Hughes Medical Institute
- Edward F Chang
Shurl and Kay Curci Foundation
- Edward F Chang
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Human subjects: All participants gave their written informed consent before surgery and affirmed it at the start of each recording session. The study protocol was approved by the University of California, San Francisco Committee on Human Research. (Protocol number 10-03842: Task-evoked changes in the electrocorticogram in epilepsy patients undergoing invasive electrocorticography and cortical mapping for the surgical treatment of intractable seizures)
Copyright
© 2020, Fox et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Transformation of a temporal speech cue to a spatial neural code in human auditory cortex
eLife 9:e53051.
https://doi.org/10.7554/eLife.53051
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