Impact of brain arousal and time-on-task on autonomic nervous system activity in the wake-sleep transition

Jue Huang,Ulrich Hegerl,Janek Spada,Tilman Hensch,Christian Sander,Philippe Jawinski,Christine Ulke

doi:10.1186/s12868-018-0419-y

Abstract

BackgroundAutonomic nervous system (ANS) activity has been shown to vary with the state of brain arousal. In a previous study, this association of ANS activity with distinct states of brain arousal was demonstrated using 15-min EEG data, but without directly controlling for possible time-on-task effects. In the current study we examine ANS-activity in fine-graded EEG-vigilance stages (indicating states of brain arousal) during two conditions of a 2-h oddball task while controlling for time-on-task. In addition, we analyze the effect of time-on-task on ANS-activity while holding the level of brain arousal constant.MethodsHeart rate and skin conductance level of healthy participants were recorded during a 2-h EEG with eyes closed under simultaneous presentation of stimuli in an ignored (N = 39) and attended (N = 39) oddball condition. EEG-vigilance stages were classified using the Vigilance Algorithm Leipzig (VIGALL 2.1). The time-on-task effect was tested by dividing the EEG into four 30-min consecutive time blocks. ANS-activity was compared between EEG-vigilance stages across the entire 2 h and within each time block.ResultsWe found a coherent decline of ANS-activity with declining brain arousal states, over the 2-h recording and in most cases within each 30-min block in both conditions. Furthermore, we found a significant time-on-task effect on heart rate, even when arousal was kept constant. It was most pronounced between the first and all subsequent blocks and could have been a consequence of postural change at the beginning of the experiment.ConclusionOur findings contribute to the validation of VIGALL 2.1 using ANS parameters in 2-h EEG recording under oddball conditions.

Highlights

Autonomic nervous system (ANS) activity has been shown to vary with the state of brain arousal
heart rate (HR) and skin conductance level (SCL) between EEG‐vigilance stages during the total 2‐h EEG recording In the ignored condition, the analyses of HR across EEGvigilance stages revealed a continuous decline from high (A1) to low (C) EEG-vigilance stages, with 14 out of 15 pair-wise comparisons reaching the significance level (1.49E−13 ≤ p ≤ .023)
We examined the association of brain arousal and ANS activity within four subsequent 30-min time blocks to control for time-on-task (Hypothesis 1)

Summary

Introduction

Autonomic nervous system (ANS) activity has been shown to vary with the state of brain arousal. This association of ANS activity with distinct states of brain arousal was demonstrated using 15-min EEG data, but without directly controlling for possible time-on-task effects. According to the scoring systems by Rechtschaffen and Kales [2] and the American Academy of Sleep Medicine [3], different sleep stages can be differentiated, but only one uniform wake state has. To fill this gap, the Vigilance Algorithm Leipzig (VIGALL), an EEG- and electrooculogram (EOG)-based algorithm, was introduced by Hegerl and colleagues [9,10,11,12,13]. A hyperstable pattern of arousal regulation was observed in patients with depression [20, 21] and bipolar patients during depressive episodes [18, 22]

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