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Front Neurosci. 2016 Oct 20;10:472. eCollection 2016.

Neural Correlates of Auditory Perceptual Awareness and Release from Informational Masking Recorded Directly from Human Cortex: A Case Study.

Author information

1
Program in Speech and Hearing Bioscience and Technology, Harvard-MIT Division of Health Sciences and TechnologyCambridge, MA, USA; Department of Neurology, Massachusetts General Hospital and Harvard Medical SchoolBoston, MA, USA.
2
Departments of Radiology and Neurosciences, University of California San Diego, La Jolla, CA, USA.
3
Department of Neurology, Ruprecht-Karls-Universität Heidelberg Heidelberg, Germany.
4
Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA.
5
Department of Neurology, Massachusetts General Hospital and Harvard Medical School Boston, MA, USA.

Abstract

In complex acoustic environments, even salient supra-threshold sounds sometimes go unperceived, a phenomenon known as informational masking. The neural basis of informational masking (and its release) has not been well-characterized, particularly outside auditory cortex. We combined electrocorticography in a neurosurgical patient undergoing invasive epilepsy monitoring with trial-by-trial perceptual reports of isochronous target-tone streams embedded in random multi-tone maskers. Awareness of such masker-embedded target streams was associated with a focal negativity between 100 and 200 ms and high-gamma activity (HGA) between 50 and 250 ms (both in auditory cortex on the posterolateral superior temporal gyrus) as well as a broad P3b-like potential (between ~300 and 600 ms) with generators in ventrolateral frontal and lateral temporal cortex. Unperceived target tones elicited drastically reduced versions of such responses, if at all. While it remains unclear whether these responses reflect conscious perception, itself, as opposed to pre- or post-perceptual processing, the results suggest that conscious perception of target sounds in complex listening environments may engage diverse neural mechanisms in distributed brain areas.

KEYWORDS:

auditory cortex; conscious perception; electrocorticography; high-gamma activity; informational masking

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