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Proc Natl Acad Sci U S A. 2016 Feb 2;113(5):E616-25. doi: 10.1073/pnas.1508523113. Epub 2016 Jan 19.

Brain responses in humans reveal ideal observer-like sensitivity to complex acoustic patterns.

Author information

1
Ear Institute, University College London, London WC1X 8EE, United Kingdom; Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom; n.barascud@ucl.ac.uk m.chait@ucl.ac.uk.
2
School of Electronic Engineering and Computer Science, Queen Mary, University of London, London E1 4NS, United Kingdom;
3
Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom; Medical School, Newcastle University, Newcastle-upon-Tyne NE2 4HH, United Kingdom.
4
Wellcome Trust Centre for Neuroimaging, University College London, London WC1N 3BG, United Kingdom;
5
Ear Institute, University College London, London WC1X 8EE, United Kingdom; n.barascud@ucl.ac.uk m.chait@ucl.ac.uk.

Abstract

We use behavioral methods, magnetoencephalography, and functional MRI to investigate how human listeners discover temporal patterns and statistical regularities in complex sound sequences. Sensitivity to patterns is fundamental to sensory processing, in particular in the auditory system, because most auditory signals only have meaning as successions over time. Previous evidence suggests that the brain is tuned to the statistics of sensory stimulation. However, the process through which this arises has been elusive. We demonstrate that listeners are remarkably sensitive to the emergence of complex patterns within rapidly evolving sound sequences, performing on par with an ideal observer model. Brain responses reveal online processes of evidence accumulation--dynamic changes in tonic activity precisely correlate with the expected precision or predictability of ongoing auditory input--both in terms of deterministic (first-order) structure and the entropy of random sequences. Source analysis demonstrates an interaction between primary auditory cortex, hippocampus, and inferior frontal gyrus in the process of discovering the regularity within the ongoing sound sequence. The results are consistent with precision based predictive coding accounts of perceptual inference and provide compelling neurophysiological evidence of the brain's capacity to encode high-order temporal structure in sensory signals.

KEYWORDS:

MEG; MMN; fMRI; pattern detection; statistical learning

PMID:
26787854
PMCID:
PMC4747708
DOI:
10.1073/pnas.1508523113
[Indexed for MEDLINE]
Free PMC Article

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