Closed-loop intracranial stimulation alters movement timing in humans

Area of Science:

• Neuroscience
• Biomedical Engineering
• Neural Prosthetics

Background:

• Human neural prosthetics aim to stimulate brain circuits synchronized with ongoing neural activity.
• The human supplementary motor area (SMA) is a key target due to its pre-movement neural activity patterns.

Purpose of the Study:

• To test a method for detecting SMA activity related to impending movement.
• To deliver cortical stimulation to influence motor timing using a closed-loop system.

Main Methods:

• Experiments involved nine epilepsy patients with intracranial electrodes.
• Electrocorticography (ECoG) localized electrodes in the SMA or control sites.
• A real-time sense-and-stimulate (SAS) system delivered electrical stimulation based on pre-movement gamma power.

Main Results:

• Stimulation in the SMA significantly slowed motor behavior in all tested patients.
• No motor behavior changes were observed when stimulation was applied at control sites.

Conclusions:

• Neurophysiological signals preceding movement can trigger closed-loop stimulation to modulate motor behavior subtly.
• This represents the first human closed-loop system for altering movement via direct cortical recording and stimulation.