Neural oscillatory dynamics in joint action: distinct contributions of entrainment and beta modulation to self/other integration

Abstract

Temporal coordination plays a pivotal role in human activities, enabling effective communication and collaboration. Yet, the neural mechanisms supporting this ability remain poorly understood. Recent research suggests that synchronized beta modulation across individual brains, as measured via EEG hyperscanning, may reflect a shared sensorimotor framework underpinning interpersonal synchronization. Building on the idea that self-other integration is a key mechanism in this process, behavioral studies have shown that adopting a partners first-person visual perspective (1P) enhances interpersonal coordination, as opposed to the natural second-person perspective (2P). Here, we used the body-swap illusion in immersive virtual reality to directly manipulate embodied perspective and investigate its neural consequences. Specifically, we examined how this illusion modulates beta activity and neural entrainment during joint rhythmic action. Forty participants (N=40), randomly paired into twenty dyads, performed a joint finger-tapping task while wearing head-mounted displays for immersive virtual environments. In coupled conditions, the visual scene was manipulated so that participants viewed their partners hand from a 1P perspective, as if it belonged to their own body, or from a natural 2P perspective. In uncoupled control conditions, participants saw their own hand in 1P and 2P, without perceiving any information about their partners tapping. EEG hyperscanning revealed that both neural entrainment (measured as the convergence of low-frequency oscillations) and beta modulation (changes in [~]20 Hz power linked to partner- generated movements) occurred in 1P and 2P visually coupled conditions. However, only beta modulation was selectively enhanced when participants experienced their partners hand from a 1P perspective. These findings suggest that while neural entrainment reflects a general mechanism for tracking a partners rhythmic behavior, beta modulation specifically supports the integration of the others effector into ones bodily representation.