Evidence for Predictive Coding in Human Auditory Cortex
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1
Univeristy of California, Berkeley, United States
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2
University of Oldenburg, Germany
Perception is often treated as a "bottom-up" process wherein early stages of processing extract low-level features of sensory information in a passive "feed-forward" manner [Griffiths and Warren, 2004]. Recent research suggests that individuals employ a more "active" process in sensory processing with higher-level regions of the brain shaping lower-level sensory processing [Schroeder et al, 2010]. Several theories for these "top-down" signals have been posited, including "predictive coding" and "biased competition" models [Clark, 2013]. The present study investigated top-down auditory processing with auditory stimuli missing acoustic information. We filtered spoken sentences from the TIMIT database using the modulation transfer function [Elliott and Theunissen, 2009], rendering the acoustic sounds unintelligible. We presented these sounds both before and after presentation of the original unaltered sentence to patients using electrocorticographic (ECoG) methods. We focused on the high gamma band (HG; 80-175 Hz) of the ECoG signal in 4 patients with subdural grids over perisylvian cortices. After hearing the original sentence, comprehension of the following filtered version is improved. We investigated the influence of complete sentence information on the neural processing of the same sentence's degraded acoustic information. We assessed whether differences were observed in auditory cortex by constructing linear encoding models of electrode response to acoustic features and comparing model fits to filtered sounds before (pre-trial) and after (post-trial) hearing the original sentence. We found that listening to a filtered sound after hearing its unaltered version enhances auditory cortex response to low-level acoustic features (all subjects, p<.05). We also show that acoustic models built from unaltered sentences provide better predictions about brain activity in the post trials conditions (all subjects, p<.05). The results provide support for predictive coding and top down control in human auditory cortices.
Keywords:
Attention,
Auditory Perception,
predictive coding,
electrocorticography,
Top-down control,
sensory processing,
encoding models
Conference:
XII International Conference on Cognitive Neuroscience (ICON-XII), Brisbane, Queensland, Australia, 27 Jul - 31 Jul, 2014.
Presentation Type:
Poster
Topic:
Language
Citation:
Holdgraf
C,
De Heer
W,
Rieger
J,
Pasley
B,
Knight
R and
Theunissen
F
(2015). Evidence for Predictive Coding in Human Auditory Cortex.
Conference Abstract:
XII International Conference on Cognitive Neuroscience (ICON-XII).
doi: 10.3389/conf.fnhum.2015.217.00122
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Received:
19 Feb 2015;
Published Online:
24 Apr 2015.
*
Correspondence:
Mr. Chris Holdgraf, Univeristy of California, Berkeley, Berkeley, United States, threefromthekey@gmail.com
Miss. Wendy De Heer, Univeristy of California, Berkeley, Berkeley, United States, deheer@berkeley.edu
Dr. Jochem Rieger, University of Oldenburg, Oldenburg, Germany, jochem.rieger@uni-oldenburg.de
Dr. Brian Pasley, Univeristy of California, Berkeley, Berkeley, United States, bpasley@berkeley.edu
Dr. Robert Knight, Univeristy of California, Berkeley, Berkeley, United States, rtknight@berkeley.edu
Dr. Frederic Theunissen, Univeristy of California, Berkeley, Berkeley, United States, theunissen@berkeley.edu