A Functional Near-Infrared Spectroscopy Study on the Cortical Haemodynamic Responses During the Maastricht Acute Stress Test

N K Schaal,O T Wolf,P Hepp,C Krampe,A Schweda

doi:10.1038/s41598-019-49826-2

Abstract

In order to better understand stress responses, neuroimaging studies have investigated the underlying neural correlates of stress. Amongst other brain regions, they highlight the involvement of the prefrontal cortex. The aim of the present study was to explore haemodynamic changes in the prefrontal cortex during the Maastricht Acute Stress Test (MAST) using mobile functional Near-Infrared Spectroscopy (fNIRS), examining the stress response in an ecological environment. The MAST includes a challenging mental arithmic task and a physically stressful ice-water task. In a between-subject design, participants either performed the MAST or a non-stress control condition. FNIRS data were recorded throughout the test. Additionally, subjective stress ratings, heart rate and salivary cortisol were evaluated, confirming a successful stress induction. The fNIRS data indicated significantly increased neural activity of brain regions of the dorsolateral prefrontal cortex (dlPFC) and the orbitofrontal cortex (OFC) in response to the MAST, compared to the control condition. Furthermore, the mental arithmetic task indicated an increase in neural activity in brain regions of the dlPFC and OFC; whereas the physically stressful hand immersion task indicated a lateral decrease of neural activity in the left dlPFC. The study highlights the potential use of mobile fNIRS in clinical and applied (stress) research.

Highlights

To date, several neuroimaging studies, utilising functional magnetic resonance imaging, have been conducted in order to investigate the underlying neural mechanisms of stress[13]
The results indicate bilateral increased neural activity in brain regions of the prefrontal cortex, more precisely of the dorsolateral prefrontal cortex and the orbitofrontal cortex (OFC), when participants completed the Maastricht Acute Stress Task (MAST) in comparison to participants who completed the non-stress control task
The results indicate a significant difference between the neural activity of the mental arithmetic compared to the hand immersion task for specific prefrontal brain regions

Summary

Introduction

Several neuroimaging studies, utilising functional magnetic resonance imaging (fMRI), have been conducted in order to investigate the underlying neural mechanisms of stress[13] These studies revealed that brain regions such as the hippocampus, the amygdala as well as cortical near-surface brain regions of the prefrontal cortex are involved when experiencing stress[14,15]. FMRI results provide essential insights about the neural underpinnings of the stress response, fMRI studies face the problem that participants are placed and investigated in a very artificial position and environment – the fMRI scanner – which might be a stressful experience for the participants itself[23,24] These artificial situations differ greatly from stressful situations experienced in everyday life, indicating the need to consider the utilisation of innovative, mobile applicable neuroimaging methods. The studies highlight that the preliminary research results should encourage researchers to examine the use of (mobile) fNIRS in real-life situations, for example to monitor patients in the operating theatre

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