Neural dynamics of change detection in crowded acoustic scenes

Ediz Sohoglu,Maria Chait

doi:10.1016/j.neuroimage.2015.11.050

Abstract

Two key questions concerning change detection in crowded acoustic environments are the extent to which cortical processing is specialized for different forms of acoustic change and when in the time-course of cortical processing neural activity becomes predictive of behavioral outcomes. Here, we address these issues by using magnetoencephalography (MEG) to probe the cortical dynamics of change detection in ongoing acoustic scenes containing as many as ten concurrent sources. Each source was formed of a sequence of tone pips with a unique carrier frequency and temporal modulation pattern, designed to mimic the spectrotemporal structure of natural sounds. Our results show that listeners are more accurate and quicker to detect the appearance (than disappearance) of an auditory source in the ongoing scene. Underpinning this behavioral asymmetry are change-evoked responses differing not only in magnitude and latency, but also in their spatial patterns. We find that even the earliest (~50ms) cortical response to change is predictive of behavioral outcomes (detection times), consistent with the hypothesized role of local neural transients in supporting change detection.

Highlights

A key aspect of the process by which our brains analyze, represent and make sense of our surroundings is the ability to rapidly detect changes in the ongoing sensory input
Group-level paired t-tests for effects of change type and scene size were performed for each time sample while controlling the family-wise error (FWE) rate using a non-parametric permutation procedure based on 5000 iterations (Maris and Oostenveld, 2007)
We investigated the dynamics of cortical change-evoked responses in rapidly unfolding, crowded acoustic scenes

Summary

Introduction

A key aspect of the process by which our brains analyze, represent and make sense of our surroundings is the ability to rapidly detect changes in the ongoing sensory input. Previous neuroimaging studies of auditory change detection suggest that changes in crowded acoustic scenes are successfully encoded by the earliest stages of cortical processing in primary auditory cortex (Puschmann et al, 2013a, 2013b). It is only later stages of processing in non-primary temporal and frontal regions that determine whether listeners report hearing a change (Gregg and Snyder, 2012; Puschmann et al, 2013a, 2013b; Gregg et al, 2014; Snyder et al, 2015). These findings are compatible with the notion that when detecting change, the behavioral outcome depends on the success of higher-level processes that extract object-based perceptual representations from acoustic scenes (Eramudugolla et al, 2005; Backer and Alain, 2012) or that maintain and compare information from prechange and postchange portions of the sensory input (Eramudugolla et al, 2005; Gregg and Samuel, 2008; Pavani and Turatto, 2008)

Objectives

Methods

Results

Conclusion