Association between Scale-Free Brain Dynamics and Behavioral Performance: Functional MRI Study in Resting State and Face Processing Task.

Masato Kasagi,Sean Tanabe,Zirui Huang,Kazuyuki Fujihara,Yusuke Suzuki,Masato Fukuda,Hitoshi Shitara,Hirotaka Kosaka,Kosuke Narita,Tomokazu Motegi,Koichi Ujita,Georg Northoff

doi:10.1155/2017/2824615

Abstract

The scale-free dynamics of human brain activity, characterized by an elaborate temporal structure with scale-free properties, can be quantified using the power-law exponent (PLE) as an index. Power laws are well documented in nature in general, particularly in the brain. Some previous fMRI studies have demonstrated a lower PLE during cognitive-task-evoked activity than during resting state activity. However, PLE modulation during cognitive-task-evoked activity and its relationship with an associated behavior remain unclear. In this functional fMRI study in the resting state and face processing + control task, we investigated PLE during both the resting state and task-evoked activities, as well as its relationship with behavior measured using mean reaction time (mRT) during the task. We found that (1) face discrimination-induced BOLD signal changes in the medial prefrontal cortex (mPFC), posterior cingulate cortex (PCC), amygdala, and fusiform face area; (2) PLE significantly decreased during task-evoked activity specifically in mPFC compared with resting state activity; (3) most importantly, in mPFC, mRT significantly negatively correlated with both resting state PLE and the resting-task PLE difference. These results may lead to a better understanding of the associations between task performance parameters (e.g., mRT) and the scale-free dynamics of spontaneous and task-evoked brain activities.

Highlights

Studies using functional magnetic resonance imaging, magnetoencephalography (MEG), and electroencephalography (EEG) have shown that spontaneous brain activity can be characterized by scale-free dynamics
In the analysis of the BOLD signal changes under the face discrimination condition relative to the control condition in this study, AMYG and fusiform face area (FFA) were activated whereas medial prefrontal cortex (mPFC) and posterior cingulate cortex (PCC) were deactivated
The deactivation we observed in midline regions such as mPFC and PCC has been observed in other studies on emotion and cognitive processing [44]

Summary

Introduction

Studies using functional magnetic resonance imaging (fMRI), magnetoencephalography (MEG), and electroencephalography (EEG) have shown that spontaneous brain activity can be characterized by scale-free dynamics. The properties of scalefree dynamics have been found in various human behaviors [3, 17] including motor behavior [7, 18, 19], perception [20], music composition [21], consciousness [22,23,24], development and maturation [25, 26], personality dimensions such as trait impulsivity [27] and extraversion [28], and selfconsciousness [16] These findings suggest a close relationship between scale-free dynamics during spontaneous brain activity and those during behavioral performance. Studies explicitly focusing on the relationship between scalefree dynamics during spontaneous brain activity ( in the infraslow frequency range as measured by fMRI) and behavioral measures during a task are still lacking

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