Closed-loop TMS–EMG
Building a low-latency, self-initiated brain stimulation setup — and using it to make people disown their own movements.
Voluntary action feels seamless: you decide to move, you move, and the movement is unmistakably yours. This project was an attempt to pull that feeling apart experimentally.
Between 2019 and 2021 I worked closely with a biomedical engineer to build a low-latency, real-time, closed-loop, self-initiated non-invasive brain stimulation setup. The system watches electromyography (EMG) from the hand, detects the earliest signature of a self-initiated movement, and fires a transcranial magnetic stimulation (TMS) pulse fast enough to evoke a movement around the moment the participant was about to move anyway. I designed the experimental setup, collected data from 60+ participants, and analysed the resulting psychological and physiological signals.
The payoff is a rare experimental handle on the sense of agency. When the stimulation-evoked movement lands in the right window, participants will report that the movement was not theirs — a denial of agency over a movement their own muscles just executed.
In the media
The setup is featured on PBS NOVA. The clip below is cued to the segment:
Outputs
This work is written up in the manuscript It wasn’t me! Inducing denials of agency with a closed-loop TMS–EMG paradigm (Wong et al., 2026), and was presented at the Association for the Scientific Study of Consciousness (Wong et al., 2022) and the Society for Neuroscience (Wong et al., 2022). The broader question of how to time mental events relative to action is taken up in (Lee et al., 2022), and the full argument forms the core of my doctoral thesis (Wong, 2022).
References
2026
2022
- TalkDisrupting the sense of agency via closed-loop TMS–EMG2022
- Dissociating action execution from consciousness of action execution: A closed-loop TMS–EMG studyIn 48th Annual Meeting of the Society for Neuroscience, 2022
- Thesis