A Little Goes a Long Way: Low Working Memory Load Is Associated with Optimal Distractor Inhibition and Increased Vagal Control under Anxiety.

Derek P Spangler,Bruce H Friedman

doi:10.3389/fnhum.2017.00043

Abstract

Anxiety impairs both inhibition of distraction and attentional focus. It is unclear whether these impairments are reduced or exacerbated when loading working memory with non-affective information. Cardiac vagal control has been related to top–down regulation of anxiety; therefore, vagal control may reflect load-related inhibition of distraction under anxiety. The present study examined whether: (1) the enhancing and impairing effects of load on inhibition exist together in a non-linear function, (2) there is a similar association between inhibition and concurrent vagal control under anxiety. During anxiogenic threat-of-noise, 116 subjects maintained a digit series of varying lengths (0, 2, 4, and 6 digits) while completing a visual flanker task. The task was broken into four blocks, with a baseline period preceding each. Electrocardiography was acquired throughout to quantify vagal control as high-frequency heart rate variability (HRV). There were significant quadratic relations of working memory load to flanker performance and to HRV, but no associations between HRV and performance. Results indicate that low load was associated with relatively better inhibition and increased HRV. These findings suggest that attentional performance under anxiety depends on the availability of working memory resources, which might be reflected by vagal control. These results have implications for treating anxiety disorders, in which regulation of anxiety can be optimized for attentional focus.

Highlights

Reviewed by: Michael Gaebler, Max Planck Institute for Human Cognitive and Brain Sciences and University of Leipzig, Germany
Anxiety Manipulation on Self-Report The effectiveness of the anticipatory noise blast paradigm in increasing state anxiety was examined with a random intercept model, in which Trial was modeled as a fixed effect on trials from the 0 Load condition
For a direct examination of threat-of-noise on heart rate variability (HRV), a random intercept model containing Trial as a fixed effect was conducted on HRV during no load (i.e., 0 Load) trials, and there was no significant effect for Trial (B = 0.056, p = 0.255)

Summary

Introduction

Results indicate that low load was associated with relatively better inhibition and increased HRV These findings suggest that attentional performance under anxiety depends on the availability of working memory resources, which might be reflected by vagal control. These results have implications for treating anxiety disorders, in which regulation of anxiety can be optimized for attentional focus. Anxiety disorders are characterized by distractibility and difficulty with focusing on daily activities (Beck et al, 2005) Such features are thought to partially result from the tendency of anxiety to impair inhibition of distractor interference, an executive function that involves overriding the influence of prepotent but irrelevant attentional stimuli (Friedman and Miyake, 2004; Bishop, 2007). Through attenuating anxiety in this way, WM load increases reduce anxiety-related impairments to inhibition and selective attention (Schutz and Davis, 2000; Bradley et al, 2010; van Dillen and Derks, 2012; Vytal et al, 2012; Clarke and Johnstone, 2013)

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