The Neural Mechanisms Underlying Coordinated Action In Joint Action

OBJECTIVE:Any form of social interaction in which two or more individuals coordinate their actions in time and space to change their environment,this form of interpersonal social interaction is often referred to as joint action.And movement coordination is usually involved in the process of joint action.Coordination in joint action affects all aspects of daily life,and in this coordination process motion simulation plays an important role in the computation of forward models related to motion prediction,as well as in the feedback process with the help of perceptual information.The role of action simulation in interpersonal coordination of actions is also inferred based on kinetic behavior-related parameters in a study of how people coordinate their actions at specific points in time when only they are unable to perceive information about others online.The present study used functional near-infrared spectroscopy(fNIRS)to explore the neural mechanisms associated with coordinated action in joint action by recording the neural activity of subjects during the task.METHODS:We recruited 30 college students(15 males,15 females)and used a modified joint jumping task paradigm.Two unfamiliar participants were paired up to perform the task together,which consisted of both individual trials and joint trials.In the individual trials,the participants randomly jumped to different target distances(35cm,70cm,105cm,140cm)to obtain baseline feedback.In the joint trials,the two participants had to jump together to complete a collaborative task with different combinations of target distances(e.g.,participant 1 jumps to 35cm,participant 2 jumps to 140cm;participant 1 jumps to 70cm,participant 2 jumps to 70cm)without observing each other’s movements.The experiment used a portable functional near-infrared spectroscopy device(NIRSport2)to measure changes in brain oxygenation metabolism,and the differences in mean beta values of oxyhemoglobin were compared across conditions using repeated measures analysis of variance.RESULTS:(1)At the behavioral level,ANOVAs were performed on the three behavioral parameters motor onset(MO),jump time(MT),and jump distance(D)for 2(jump condition:single vs double with same distance)× 4(jump distance:35cm vs 70cm vs 105cm vs 140cm)repeated measures,respectively.The relationship between jumping distance and the three behavioral parameters was confirmed,with the longer MO and MT and the longer D the farther the subjects jumped from the target distance.It was shown that for the same distance jumped,the MO increased significantly and the MT decreased significantly in the single jump compared to the double distance condition,but there was no significant difference in the parameter D between the two conditions.These results suggest that although the jumping distances are the same,the presence of a partner in a cooperative task requirement affects the individual’s jumping performance.The three relative difference scores rMO,rMT and rD obtained through the calculation were subjected to ANOVA for repeated measures of 2(jumping relationship:closer to oneself vs further away from oneself)x 3(jumping distance difference:Δ35cm vs Δ70cm vs Δ105cm),respectively.The results showed that the greater the distance difference between jumping with a partner in the condition of being closer to oneself,the greater the rMO value.This indicates that one prolongs one’s motor preparation time as the distance difference between one’s and one’s partner’s jumps increases.In contrast,no association between the jumping relationship and the jumping distance difference was found in the parameters rMT and rD.(2)At the neural level,an ANOVA with repeated measures of 2(jumping relationship:two-people same distance vs closer to oneself)× 3(jumping distance:35cm vs 70cm vs 105cm)was performed for the Beta[HbO]values of ROI-1 and ROI-2 in the region of interest,respectively.The results showed that the main effect of jumping relationship was significant in both ROI-1 and ROI-2,indicating that the activation in the corresponding brain regions was significantly higher in the closer to oneself condition than in the twoperson distance condition.The interaction between jumping relationship and jumping distance was significant,and post hoc tests revealed that the main effect of jumping relationship in ROI-1 was mainly on jumping distance of 105 cm;in ROI-2 the main effect of jumping relationship was mainly on jumping distance of 70 cm and 105 cm.Repeated-measures ANOVAs were conducted on the Beta[HbO]values of ROI-1 and ROI-2 in the region of interest for 2(jumping relationship:two people with the same distance vs further away from themselves)x 3(jumping distance:70cm vs 105cm vs 140cm),respectively.The results showed that the main effect of the jumping relationship was significant only in ROI-2,indicating that activation in the corresponding brain region was significantly higher in the own-farther condition than in the two-person distance condition.ANOVAs were performed for repeated measures of 2(jump relationship:single jump vs double co-distance)×4(jump distance:35cm vs 70cm vs 105cm vs 140cm)for the Beta[HbO]values of interest regions ROI-1 and ROI-2,respectively.The results showed that the main effect of jump relationship was significant only in ROI-1,indicating that there was a significant difference between the activation of brain areas corresponding to single jumps and those corresponding to two people with the same distance.The interaction between jumping relationship and jumping distance was significant,and post hoc tests revealed that the main effect of jumping relationship in ROI-1 was mainly for jumping distances of 35 cm and 105 cm.CONCLUSIONS:At the behavioral level:(1)When subjects jumped the same distance,the time corresponding to the motor preparation phase was longer and the time corresponding to the motor execution phase was shorter in the solo jumping condition compared to the synchronized coordination condition with a partner.(2)When the distance difference between jumps with a cooperative partner was greater,the time spent in the motor preparation phase was longer,and this effect was present only in the side with the shorter jumps.At the neural level:(1)In the tandem jumping task,subjects had greater activation in brain areas corresponding to the dorsolateral prefrontal lobe when the partner jumped further compared to the same distance as the partner.(2)In the tandem jumping task,whether the partner jumped farther or closer,there was greater activation in brain areas associated with the motor cortex compared to the condition in which both subjects jumped the same distance.(3)When subjects jumped the same distance,there was greater activation in the dorsolateral prefrontal lobe in the solo jumping condition compared to the synchronized coordination condition with the partner.