S69. NEURAL-SYNCHRONIZATION DURING COOPERATION TASK IN CLINICAL HIGH RISK OF PSYCHOSIS-A FNIRS-BASED HYPERSCANNING STUDY

Abstract

Background

A growing evidence has been reported that patients at clinical-high risk(CHR) for psychosis showed deficits in social interaction. A pervasive challenge in social neuroscience is how to model human interactions in laboratory to study the dynamic of brain activity. Functional near-infread spectroscopy(fNIRS) is a relatively convenient cortical imaging technology that can measuring brain activity in a more naturalistic environment. We developed a hyperscanning method to simultaneously measure brain activity in two people during a computer-based game.

Methods

Participants:Sixty-four adults from SHARP group(32 pairs, 15 pairs of healthy-healthy(HC-HC), mean age: 26.6±4.3，mean education: 17.1 ± 3.1; 17 pairs of healthy-CHR(HC-CHR), mean age: 24.1 ± 5.8, mean education: 15.0 ± 4.0) participated in the study. There were 7 female–female pairs and 8 male–male pairs in the HC-HC group, while 11 female-female pairs, 5 male-male pairs and 1 female-male pair in the HC-CHR group. Written informed consent was obtained from all participants, and the study protocol was approved by the ethics committee of Shanghai Mental Health Center.

Computer-based Game:Each pair participated in a computer-based “cooperation” and “competition” tasks, a hollow gray circle appeared and remained on the screen. After a random delay of 0.6–1.5 s, the gray circle filled with a green circle (‘go’ signal). The participants were instructed to press their response keys only after the ‘go’ signal. The participant on the left was instructed to use the ‘1’ key, the right use the ‘0’ key. We will denote the time between the ‘go’ signal and the key press as the “response time.” If the difference between the response times of the two participants was smaller than a threshold, both participants earned one point; otherwise they both lost one point. They were instructed to maximize the number of points earned. While competition task, participants were instructed to respond faster than their partners

NIRS data acquisition: ETG-4000 (Hitachi, Japan) was used to measure the concentration changes in oxygenated hemoglobin (oxy-Hb) and deoxygenated hemoglobin (deoxy-Hb). A single “3×5” patch consisting of 8 emitters and 7 detectors was positioned on each participant’s forehead resulting in 22 measurement channels. The patch placement was based on the 10–20 system. Wavelet coherence was used to assess relationships between NIRS signals by a pair of participants.

Results

Reaction time among participant pairs between competition and cooperation task showed no significant (t=-0,854, p=0.396). HC-HC group showed higher success rate during the cooperation task (t=2.525, p=0.017). For each channel, after converting the synchronization increase into a Z value. Based on uncorrected p value, a significant activation coherence in channel 3(t=4.65, p=0.02), channel 9(t=8.17, p=0.009) and channel 14(t=5.72, p=0.025) were found between groups. After correction there is no significant activation coherence.

Discussion

The technique of hyperscanning is a new method to study the neural-synchronization in CHR. This just was a preliminary result. Because of the limitation of sample size, we just observed a meaningful activation coherence based on uncorrected p value. Our study is still going on and intends to collect 30 HC-HC dyads and 30 HC-CHR dyads. When completed we will reanalyze the data and wish to report on the SIRS.