NIRS-Based Hyperscanning Reveals Inter-brain Neural Synchronization during Cooperative Jenga Game with Face-to-Face Communication

Abstract

Functional near-infrared spectroscopy (fNIRS) is an increasingly popular technology for studying social cognition. In particular, fNIRS permits simultaneous measurement of hemodynamic activity in two or more individuals interacting in a naturalistic setting. Here, we used fNIRS hyperscanning to study social cognition and communication in human dyads engaged in cooperative and obstructive interaction while they played the game of Jenga™. Novel methods were developed to identify synchronized channels for each dyad and a structural node-based spatial registration approach was utilized for inter-dyad analyses. Strong inter-brain neural synchrony (INS) was observed in the posterior region of the right middle and superior frontal gyrus, in particular Brodmann area 8 (BA8), during cooperative and obstructive interaction. This synchrony was not observed during the parallel game play condition and the dialog section, suggesting that BA8 was involved in goal-oriented social interaction such as complex interactive movements and social decision-making. INS was also observed in the dorsomedial prefrontal cortex (dmPFC), in particular Brodmann 9, during cooperative interaction only. These additional findings suggest that BA9 may be particularly engaged when theory-of-mind (ToM) is required for cooperative social interaction. The new methods described here have the potential to significantly extend fNIRS applications to social cognitive research.

Keywords: cooperation; fNIRS; functional near-infrared spectroscopy; hyperscanning; inter-brain neural synchronization (INS); obstructive interaction.

Figure 1

Task design (A), experimental setup (B) and probe configuration (C).

Figure 2

The location of coherence for a representative dyad. Green triangles represent the channel locations of subject 1; the green numbers label the channel indices; and the green area represents the probe coverage of subject 1. Blue squares and numbers represent the channel locations and indices of subject 2, and the blue area represents the probe coverage of subject 2. Channels were paired to their closest neighboring points within 15 mm distance, and the middle points of the paired channels were defined as the location of the coherence, represented by red dots. Dashed lines connect the paired channels for representative purposes.

Figure 3

Paired subjects wavelet coherences analysis. (A) Regressors for general linear model (GLM) analysis. Each color line indicates an experimental condition and the black line indicates rest. (B) Wavelet coherence map for a representative dyad.

Figure 4

Social interaction frequency during three task conditions (bars represent standard deviation).

Figure 5

The structural node-based spatial registration approach for inter-dyad analyses. (A) The measured channel locations of all dyads on a MRI rendered brain template. (B) The measured channel locations of all dyads at rPFC region in 3D space. The red dots represent the effective locations of all dyads; the green dots represent the nodes that cover the measured cortical region; and the blue squares mark the nodes that have data from ≥8 subjects within 15 mm diameter distance from that node. Overlap map shows the distribution of the number of dyads that were measured by functional near-infrared spectroscopy (fNIRS): (C) at rPFC region, and (D) at rSTS region. Colorbar indicates the number of subjects that fall within 15 mm diameter distance from the node.

Figure 6

Group t-maps for the contrast corresponding to coherence (A) in the cooperation condition vs. rest, and (B) in obstructive interaction condition vs. rest. (C) T-values at a node that was significantly synchronized in both cooperation and obstruction conditions (vs. rest). (D) T-values at a node that was significantly synchronized only in the cooperation condition (vs. rest).

Figure 7

The effective nodes for the contrast corresponding to coherence (A) in the cooperation vs. dialog condition; (B) in the obstructive interaction vs. dialog condition.