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Noise in Brain Activity Engenders Perception and Influences Discrimination Sensitivity.
MedLine Citation:
PMID:  22159111     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Behavioral and brain responses to identical stimuli can vary with experimental and task parameters, including the context of stimulus presentation or attention. More surprisingly, computational models suggest that noise-related random fluctuations in brain responses to stimuli would alone be sufficient to engender perceptual differences between physically identical stimuli. In two experiments combining psychophysics and EEG in healthy humans, we investigated brain mechanisms whereby identical stimuli are (erroneously) perceived as different (higher vs lower in pitch or longer vs shorter in duration) in the absence of any change in the experimental context. Even though, as expected, participants' percepts to identical stimuli varied randomly, a classification algorithm based on a mixture of Gaussians model (GMM) showed that there was sufficient information in single-trial EEG to reliably predict participants' judgments of the stimulus dimension. By contrasting electrical neuroimaging analyses of auditory evoked potentials (AEPs) to the identical stimuli as a function of participants' percepts, we identified the precise timing and neural correlates (strength vs topographic modulations) as well as intracranial sources of these erroneous perceptions. In both experiments, AEP differences first occurred ∼100 ms after stimulus onset and were the result of topographic modulations following from changes in the configuration of active brain networks. Source estimations localized the origin of variations in perceived pitch of identical stimuli within right temporal and left frontal areas and of variations in perceived duration within right temporoparietal areas. We discuss our results in terms of providing neurophysiologic evidence for the contribution of random fluctuations in brain activity to conscious perception.
Authors:
Fosco Bernasconi; Marzia De Lucia; Athina Tzovara; Aurelie L Manuel; Micah M Murray; Lucas Spierer
Publication Detail:
Type:  JOURNAL ARTICLE    
Journal Detail:
Title:  The Journal of neuroscience : the official journal of the Society for Neuroscience     Volume:  31     ISSN:  1529-2401     ISO Abbreviation:  -     Publication Date:  2011 Dec 
Date Detail:
Created Date:  2011-12-13     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8102140     Medline TA:  J Neurosci     Country:  -    
Other Details:
Languages:  ENG     Pagination:  17971-17981     Citation Subset:  -    
Affiliation:
Neuropsychology and Neurorehabilitation Service, Department of Clinical Neurosciences, Department of Psychiatry, Community Psychiatry Service, and Radiology Department, Vaudois University Hospital Center and University of Lausanne, 1011 Lausanne, Switzerland, Electroencephalography Brain Mapping Core, Center for Biomedical Imaging, 1011 Lausanne, Switzerland, Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0014, and Neurology Unit, Medicine Department, University of Fribourg, 1700 Fribourg, Switzerland.
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