Hyper-Transcranial Alternating Current Stimulation: Experimental Manipulation of Inter-Brain Synchrony

Area of Science:

• Neuroscience
• Social Cognition
• Human-Computer Interaction

Background:

• Interpersonal coordination is vital for social interaction.
• Neural synchronization across brains is hypothesized to facilitate coordinated actions.
• Transcranial alternating current stimulation (tACS) offers a tool to investigate brain synchronization.

Purpose of the Study:

• To directly test if brain-to-brain synchronization via hyper-tACS enhances interpersonal action coordination.
• To investigate the neural mechanisms underlying synchronized dyadic actions.

Main Methods:

• Thirty-eight female dyads performed synchronized drumming for 3 weeks.
• Three hyper-tACS conditions were applied: same-phase-same-frequency, different-phase-different-frequency, and sham.
• Stimulation targeted right frontal and parietal sites in the theta frequency range.

Main Results:

• Contrary to hypotheses, both same-phase-same-frequency and different-phase-different-frequency tACS conditions increased drumming asynchrony compared to sham.
• No significant effects of hyper-tACS were observed on drumming alone to a metronome.
• Individual and dyad preferred drumming tempos remained unaffected by tACS.

Conclusions:

• The study challenges the hypothesis that direct brain-to-brain theta-band synchronization via hyper-tACS improves interpersonal action coordination.
• Current hyper-tACS paradigms may have limitations in modulating complex social behaviors.
• Further research is needed to explore alternative neural mechanisms and stimulation approaches for interpersonal coordination.