Summary
A bioRxiv preprint reports that intracortical signals predicted movement onset 250–400 milliseconds ahead in three people with tetraplegia. Participants reported intending to act on 88% of trials when a virtual opponent interrupted them.
A bioRxiv preprint reports that intracortical signals from motor cortex predicted movement onset 250–400 milliseconds before action in three people with tetraplegia and preserved wrist extension. In a timing game, a virtual opponent used a real-time decoder to detect activity associated with an impending movement and pre-empt participants. The authors interpret the decoded state as a late commitment to act that aligns with participants’ reported intentions.
A timing game tested whether the signal marked an intention to act
Preparatory neural activity can occur before movement, but its relationship to a person’s decision to act is debated. To examine that link, the researchers set up a strategic game in which participants tried to act unpredictably while a virtual opponent monitored their intracortical sensorimotor activity.
The decoder predicted movement onset 250–400 milliseconds before the action. Participants were pre-empted on 94% of trials. They reported that they had intended to act on 88% of those interrupted trials, and movement output generally followed despite the interruption.
The reports connect the decoded brain state to participants’ own experience of intending to move. The experiment therefore offers evidence about the timing of a motor-cortical signal in relation to reported intention—not a direct readout of subjective experience.
The decoder also worked in a non-competitive task
The researchers used the same decoder to predict participants’ actions in a non-competitive task, without retraining it. This result suggests that the signal detected in the timing game was not confined to that competitive setup. The authors describe it as a task-independent motor-cortical state marking a voluntary commitment to act.
The study involved three people, and its central link between decoded activity and conscious intention depends in part on participants’ reports after interruption. The findings are presented in a bioRxiv preprint, rather than a peer-reviewed journal article. They offer a small-scale human result on how motor-cortex activity relates to impending action, with broader application to other people and tasks still to be established.