A roadmap for the study of conscious audition and its neural basis

Abstract

How and which aspects of neural activity give rise to subjective perceptual experience-i.e. conscious perception-is a fundamental question of neuroscience. To date, the vast majority of work concerning this question has come from vision, raising the issue of generalizability of prominent resulting theories. However, recent work has begun to shed light on the neural processes subserving conscious perception in other modalities, particularly audition. Here, we outline a roadmap for the future study of conscious auditory perception and its neural basis, paying particular attention to how conscious perception emerges (and of which elements or groups of elements) in complex auditory scenes. We begin by discussing the functional role of the auditory system, particularly as it pertains to conscious perception. Next, we ask: what are the phenomena that need to be explained by a theory of conscious auditory perception? After surveying the available literature for candidate neural correlates, we end by considering the implications that such results have for a general theory of conscious perception as well as prominent outstanding questions and what approaches/techniques can best be used to address them.This article is part of the themed issue 'Auditory and visual scene analysis'.

Keywords: audition; auditory scene analysis; conscious perception; neural correlates of consciousness; perceptual awareness.

Figure 1.

Schematic illustrations of three popular stimulation paradigms in the study of auditory scene analysis and conscious auditory perception. (a) The ABA-streaming paradigm, in which the same physical stimulus can give rise to two different percepts (one stream or two). (b) The jittered multitone masker paradigm, in which the regularly repeating target tones (shown in blue) are only sometimes perceived. (c) The stochastic figure-ground paradigm, where the coherence of certain spectral elements in and across time can give rise to the perception of an auditory figure distinct from the background. Reproduced from [112].

Figure 2.

Recent results showing characteristic source topographies and waveform morphologies of both the mismatch negativity (MMN) (panels a–c) and awareness-related negativity (ARN) (panels d–f). (a) Typical source topography of the MMN, with sources in anterolateral portions of human AC. (b) Source waveforms of responses to standard tones (black), deviant tones (grey) and their subtraction (deviants minus standards, lower panels), clearly revealing the MMN as a prominent negativity between 100 and 200 ms. (c) Associated amplitude quantifications. (d) Source waveforms for virtual targets, i.e. targets that were absent (grey), detected and undetected standard tones (solid and transparent blue, respectively), detected and undetected deviant tones (solid and transparent orange, respectively), and their respective difference waveforms (lower panels). Panel (d) shows both the ARN as a strong, negative-going deflection in response to detected targets as well as the fact that when embedded in the multitone masker cloud, the MMN was only elicited when the standard stream was detected prior to the occurrence of the deviant. (e) Corresponding source locations and amplitude quantifications (f). Reproduced from [110].