Abstract
In complex acoustic environments, even suprathreshold sounds that are faithfully represented in the ascending auditory pathway sometimes go unperceived, a phenomenon termed informational masking. Little is known regarding the large-scale brain dynamics giving rise to conscious perception under informational masking, particularly outside auditory cortex. To examine this question, we combined simultaneous M/EEG with trial-by-trial perceptual reports and anatomically constrained distributed source estimates. Listeners reported the moment at which they became aware of spectrally isolated and otherwise suprathreshold tone streams rendered sometimes inaudible by random multitone masker “clouds.” While all targets elicited early responses in auditory cortex, later auditory-cortex activity (peaking between 150 and 200 ms) was only observed for targets that were detected. A robust P3-like response with distributed sources was observed for the second detected target (immediately preceding listeners' reports), and was greatly diminished or absent for prior and subsequent targets. The results highlight late, distributed aspects of neuronal activity associated with task-related post-perceptual processing (i.e., task relevance), but argue against this activity underlying conscious perception, per se.
Published Version
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