Primary motor cortex and free will

Our latest research sheds new light on how the human brain turns intentions into real-world actions. In collaboration with a tetraplegic participant using a brain–machine interface (BMI), we were able to explore, for the first time, the full chain from the thought of moving to the physical movement and its effects in the environment.

By combining brain signals from the primary motor cortex (M1) with neuromuscular electrical stimulation (NMES) to generate real hand movements, we could independently manipulate each step in this chain: intention, action, and effect. This unique setup allowed us to probe both the participant's subjective experience and the underlying brain activity.

We discovered a novel form of intentional binding: people perceive their intention and the resulting movement as happening closer together in time. At the neural level, we found that spikes in M1 neurons coincided with the participant’s reported feeling of intention. Remarkably, both the strength of this brain activity and the timing of the subjective experience varied together from trial to trial.

Our findings also showed that population-level brain dynamics — the patterns driving movement — reflect this tight link between intention and action.

This study fills an important gap in neuroscience by connecting single-neuron activity in human M1 with the conscious experience of intending to act. It also complements earlier work on pre-motor and parietal regions, bringing us closer to understanding how voluntary actions are generated in the brain.

Beyond the scientific insight, this research could help improve brain-controlled technologies, making them feel more natural and intuitive for users.