Inter-Brain Synchrony in Open-Ended Collaborative Learning: An fNIRS-Hyperscanning Study

Summary

The protocol for conducting fNIRS hyperscanning experiments on collaborative learning dyads in a naturalistic learning environment is outlined. Further, a pipeline to analyze the Inter-Brain Synchrony (IBS) of oxygenated hemoglobin (Oxy-Hb) signals is presented.

Abstract

fNIRS hyperscanning is widely used to detect the neurobiological underpinnings of social interaction. With this technique, researchers qualify the concurrent brain activity of two or more interactive individuals with a novel index called inter-brain synchrony (IBS) (i.e., phase and/or amplitude alignment of the neuronal or hemodynamic signals across time). A protocol for conducting fNIRS hyperscanning experiments on collaborative learning dyads in a naturalistic learning environment is presented here. Further, a pipeline of analyzing IBS of oxygenated hemoglobin (Oxy-Hb) signal is explained. Specifically, the experimental design, the process of NIRS data recording, data analysis methods, and future directions are all discussed. Overall, implementing a standardized fNIRS hyperscanning pipeline is a fundamental part of second-person neuroscience. Also, this is in line with the call for open-science to aid the reproducibility of research.

Introduction

Recently, to reveal the concurrent brain activity across the interactive dyads or members of a group, researchers employ the hyperscanning approach^1,2. Specifically, electroencephalogram (EEG), functional magnetic resonance imaging (fMRI), and functional near-infrared spectroscopy (fNIRS) are used to record the neural and brain activities from two or more subjects simultaneously^3,4,5. Researchers extract a neural index entailing concurrent brain coupling based on this technique, which refers to inter-brain synchrony (....

Protocol

All recruited participants (40 dyads, mean age 22.1 ± 1.2 years; 100% right-handed; normal or corrected-to-normal vision) were healthy. Before the experiment, participants gave informed consent. Participants were financially compensated for their participation. The study was approved by the University Committee of Human Research Protection (HR-0053-2021), East China Normal University.

1. Preparation steps before adopting data

1. Homemade NIRS caps
   1. Adopt elastic swimming cap to place optode holder grid.
      NOTE: Considering that the head sizes of the participants are different, two sizes of caps are used. Small caps a....

Results

Figure 1 illustrates the experimental protocol and probe location. The fNIRS data recording process consists of two parts: resting-state session (5 min) and collaborative session (15-20 min). The collaborative learning dyads are required to relax and to keep still in the resting-state session. After that, participants are told to co-learning the learning material (Figure 1A). Their prefrontal and left temporoparietal regions are covered by the corresponding prob.......

Discussion

First, in the present protocol, the specific steps of conducting fNIRS hyperscanning experiments in a collaborative learning scenario are stated. Second, the data analysis pipeline that assesses the IBS of hemodynamic signals in collaborative learning dyads is also presented. The detailed operation on conducting fNIRS hyperscanning experiments would promote the development of open-science. Furthermore, the analysis pipeline is provided here to increase the reproducibility of hyperscanning research. In the following, the .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
EEG caps	Compumedics Neuroscan,Charlotte,USA	64-channel Quik-Cap	We choose two sizes of cap(i.e.medium and large).
NIRS measurement system with probe sets and probe holder grids	Hitachi Medical Corporation, Tokyo, Japan	ETG-7100 Optical Topography System	The current study protocol requires an optional second adult probe set for 92 channels of measurement in total.
Numeric computing platform	The MathWorks, Inc., Natick, MA	MATLAB R2020a	Serves as base for Psychophysics Toolbox extensions (stimulus presentation), Homer2  (fNIRS preprocess analysis), and "wtc" function(WTC computation).
Psychology software	psychology software tools,Sharpsburg, PA,USA	E-prime 2.0	We apply E-prime to start the fNIRS measurement system and send triggers which marking the rest phase and collaborative learning phase for fNIRS recording data.
Swimming caps	Zoke corporation,Shanghai,China	611503314	We first placed the standard 10-20 EEG cap on the head mold, and placed the swimming cap on the EEG cap. Second, we marked (inion, Cz, T3, T4, PFC and P5) with chalk.
Three-dimensional (3-D) digitizer	Polhemus, Colchester, VT, USA;	Three-dimensional (3-D) digitizer	Anatomical locations of optodes in relation to standard head landmarks were determined for each participant using a Patriot 3D Digitizer