Brain-to-Brain Synchrony during Social Cooperation in Autism – a NIRS-Based Hyperscanning Study

Background: In healthy adults, synchronization of brain activation has repeatedly been demonstrated during joint social tasks, and may play an important role for successful dyadic social interaction. Pioneering studies have demonstrated diminished brain-to-brain synchrony in adults with autism spectrum disorder (ASD) during such tasks, e.g. during performance of a real-time joint-attention task. To date, no study has investigated brain-to-brain synchrony in children with ASD during social interaction. Importantly, the familiarity of the interaction partner (i.e. a familiar person or a stranger) may modulate synchronization of brain activation.

Objectives: We investigated brain-to-brain synchrony in children and adolescents with and without ASD during a social cooperation game that the participants played with either a parent or an adult stranger as their interaction partner.

Methods: Using functional Near-Infrared Spectroscopy (fNIRS) hyperscanning, we assessed brain-to-brain synchrony during performance of a cooperative and a competitive computer game in 43 typically developing (TD) children, 15 children with ASD (8-18 years, all males) while playing with one of their parents, mostly mothers. In addition, adult strangers performed the identical game with each participating child. Participants were instructed to either respond jointly (as simultaneously as possible) via button press in response to a target (cooperation task), or to respond faster than the other player (competition task). Within each dyad, wavelet coherence was calculated for corresponding channels as a measure of brain-to-brain synchrony.

Results: On the behavioral level, preliminary results showed that the dyad’s cooperative performance was neither influenced by the interaction partner (parent or stranger) nor by the group (TD or ASD group). However, during competition, the child won more often against the parent than against the stranger, and children with ASD won more often against parent/stranger than TD children. On the neural level, preliminary results revealed a significant interaction of partner and group for coherence in channels 2 and 4, which correspond to Brodmann areas 8 and 9. Breaking down the two-way interaction, results revealed that coherence in the ASD group was significantly smaller when playing with the parent compared to an adult stranger. No significant effect of partner was observed in the TD group.

Conclusions: Data collection in the ASD sample is ongoing. Preliminary results suggest differential coherence in ASD with respect to the familiarity of the interaction partner. In a larger sample it remains to be seen, whether fNIRS hyperscanning represents a valuable tool for investigating brain synchrony during social tasks as a proxy for typical and atypical social interaction. To this end, we will also analyze the relation of brain-to-brain synchrony with symptom severity measures and treatment related changes.