Processing of fMRI-related anxiety and bi-directional information flow between prefrontal cortex and brain stem

Gert Pfurtscheller,Maciej Kaminski,Gerhard Schwarz,Katarzyna J Blinowska,Wolfgang Klimesch,Andreas R Schwerdtfeger,Beate Rassler

doi:10.1038/s41598-021-01710-8

Abstract

Brain–heart synchronization is fundamental for emotional-well-being and brain–heart desynchronization is characteristic for anxiety disorders including specific phobias. Recording BOLD signals with functional magnetic resonance imaging (fMRI) is an important noninvasive diagnostic tool; however, 1–2% of fMRI examinations have to be aborted due to claustrophobia. In the present study, we investigated the information flow between regions of interest (ROI’s) in the cortex and brain stem by using a frequency band close to 0.1 Hz. Causal coupling between signals important in brain–heart interaction (cardiac intervals, respiration, and BOLD signals) was studied by means of Directed Transfer Function based on the Granger causality principle. Compared were initial resting states with elevated anxiety and final resting states with low or no anxiety in a group of fMRI-naïve young subjects. During initial high anxiety the results showed an increased information flow from the middle frontal gyrus (MFG) to the pre-central gyrus (PCG) and to the brainstem. There also was an increased flow from the brainstem to the PCG. While the top-down flow during increased anxiety was predominant, the weaker ascending flow from brainstem structures may characterize a rhythmic pacemaker-like activity that (at least in part) drives respiration. We assume that these changes in information flow reflect successful anxiety processing.

Highlights

Brain–heart synchronization is fundamental for emotional-well-being and brain–heart desynchronization is characteristic for anxiety disorders including specific phobias
It is quite evident that being placed in an MRI machine induces unwellnes, fear or anxiety and in some cases even claustrophobic reactions, little is known how different levels of state anxiety affect BOLD signals, it is reasonable to assume that healthy young MRI participants, without any former scanner experience, felt increased anxiety at least in initial sessions
The causal coupling between six investigated signals as a function of frequency and time as estimated by means of ffDTF is illustrated in Fig. 2 for an exemplary individual

Summary

Introduction

Brain–heart synchronization is fundamental for emotional-well-being and brain–heart desynchronization is characteristic for anxiety disorders including specific phobias. In a recently published review article about brain–heart desynchronization in AD, Tumati et al.[5] observed neuro-cardiac desynchronization that was accompanied by a decrease in serotonergic and noradrenergic activity with abnormal connectivity of different neural networks as well as vascular and neural BOLD components at ~ 0.1 Hz. it is quite evident that being placed in an MRI machine induces unwellnes, fear or anxiety and in some cases even claustrophobic reactions, little is known how different levels of state anxiety affect BOLD signals, it is reasonable to assume that healthy young MRI participants, without any former scanner experience, felt increased anxiety at least in initial sessions. BOLD oscillations are complex signals comprising different components[15,16] that often are associated with oscillatory neural a ctivity[17,18] and with movements

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