Is your brain aware of your movement before you decide?

The Intentional Chain

• Benjamin Libet’s work in the 1980s explored the intentional chain, which includes an intent, action, and effect.

• The intentional chain was not fully studied due to technical challenges.

The Intentional Chain Experiment

• Jean-Paul Noel and colleagues from the University of Minnesota conducted an experiment in PLoS Biology.

• They found that conscious recognition of the intent to move coincides with activation in the M1 cortical area, the part of the brain controlling voluntary limb movements.

The First Study of its Kind

• The study involved a tetraplegic person with a brain implant in his M1 area.

• Electrical impulses from the implant stimulated the area, allowing researchers to activate or inactivate individual components of the intentional chain.

• The participant held a ball in his hand, emitted a sound 300 ms later, which was the environmental effect, the last piece of the intentional chain.

Rearing Up

• The desire for voluntary movement is reflected as electrical activity in specific parts of the brain.

• German scientist Hans Helmut Kornhuber found that in the moments leading up to an individual pressing a button, the electrodes recorded a gradual increase in the strength of an electric signal, which he called the readiness potential.

• This suggests that certain brain circuits are activated before an individual is aware of their intention to perform a voluntary movement.

Study on Intention and Action in the Brain

• Researchers used functional MRI and NMES to measure each step of the intentional chain.

• Participants’ subjective perceptions of their intention and the movement of their hand were compared to objective measurements.

• Participants perceived their intention to occur earlier than the full intentional chain, even when the hand movement signal was blocked from NMES.

• The study found that participants perceived a shorter time interval between a voluntary action and its effect, known as the intentional binding.

• The study also revealed the role of the M1 area in the start of a conscious decision to take action and during execution.

• The study shows that the M1 area integrates signals from premotor-parietal areas, explaining its activity in the moments leading up to the voluntary action.

• The study’s findings are based on a single tetraplegic participant, raising questions about their generalizability.

• A study by Noel and Italian scientist Tommaso Bertoni supported the role of the M1 area in translating voluntary decisions to actions.