Decoding Spatial Versus Non-spatial Processing in Auditory Working Memory.

Mira Erhart,Stefan Czoschke,Jochen Kaiser,Christoph Bledowski,Cora Fischer

doi:10.3389/fnins.2021.637877

Mira Erhart, Stefan Czoschke + Show 3 more

Open Access

https://doi.org/10.3389/fnins.2021.637877

Copy DOI

Abstract

ObjectiveResearch on visual working memory has shown that individual stimulus features are processed in both specialized sensory regions and higher cortical areas. Much less evidence exists for auditory working memory. Here, a main distinction has been proposed between the processing of spatial and non-spatial sound features. Our aim was to examine feature-specific activation patterns in auditory working memory.MethodsWe collected fMRI data while 28 healthy adults performed an auditory delayed match-to-sample task. Stimuli were abstract sounds characterized by both spatial and non-spatial information, i.e., interaural time delay and central frequency, respectively. In separate recording blocks, subjects had to memorize either the spatial or non-spatial feature, which had to be compared with a probe sound presented after a short delay. We performed both univariate and multivariate comparisons between spatial and non-spatial task blocks.ResultsProcessing of spatial sound features elicited a higher activity in a small cluster in the superior parietal lobe than did sound pattern processing, whereas there was no significant activation difference for the opposite contrast. The multivariate analysis was applied using a whole-brain searchlight approach to identify feature-selective processing. The task-relevant auditory feature could be decoded from multiple brain regions including the auditory cortex, posterior temporal cortex, middle occipital gyrus, and extended parietal and frontal regions.ConclusionIn summary, the lack of large univariate activation differences between spatial and non-spatial processing could be attributable to the identical stimulation in both tasks. In contrast, the whole-brain multivariate analysis identified feature-specific activation patterns in widespread cortical regions. This suggests that areas beyond the auditory dorsal and ventral streams contribute to working memory processing of auditory stimulus features.

Highlights

A central question in neuroscientific research on human working memory (WM) concerns the brain regions involved in the processing of memory contents
Consistent with the view that elementary stimulus features are maintained in sensory regions (Pasternak and Greenlee, 2005), multivoxel pattern analysis (MVPA) has revealed a persistent stimulus-specific activity in the sensory cortex (Harrison and Tong, 2009; Serences et al, 2009; Christophel et al, 2012; Riggall and Postle, 2012; Emrich et al, 2013; Peters et al, 2015) and in specialized areas along the processing hierarchy (Riggall and Postle, 2012; Christophel and Haynes, 2014)
While sensory recruitment seems to be an important feature of stimulus processing in WM, the representation of stimulus-specific information in the fronto-parietal cortex may depend on task demands (Lee et al, 2013; Bettencourt and Xu, 2016; Christophel et al, 2017; Xu, 2017)

Summary

Introduction

A central question in neuroscientific research on human working memory (WM) concerns the brain regions involved in the processing of memory contents. Electrophysiological and anatomical studies in monkeys have suggested that the ventral, pattern processing stream involves the anterior auditory cortex and anterior temporal and inferior frontal cortices, whereas the dorsal, space processing stream includes the posterior auditory cortex, and posterior parietal and superior frontal regions (Romanski et al, 1999; Tian et al, 2001). Both neuropsychological and functional imaging work in humans has provided converging evidence for this division (Alain et al, 2001; Clarke et al, 2002; Arnott et al, 2004; Altmann et al, 2007)

Methods

Results

Discussion

Conclusion