Closed-loop control of spinal cord stimulation to restore hand function after paralysis

Area of Science:

• Neuroscience
• Biomedical Engineering
• Rehabilitation Medicine

Background:

• Upper-limb paralysis from spinal cord injury or stroke lacks effective cures.
• Controlling robotic arms with brain activity is promising but restoring limb function remains difficult.
• Previous work showed cervical spinal cord stimulation can elicit functional upper-limb movements in monkeys.

Purpose of the Study:

• To demonstrate closed-loop cortical control of spinal cord stimulation in awake animals.
• To bypass disrupted corticospinal pathways and restore upper-limb function.
• To test a neural prosthesis for improving hand function after motor cortex disruption.

Main Methods:

• Monkeys were trained on a grasp-and-pull task.
• Primary motor cortex was reversibly inactivated using muscimol.
• Ventral premotor cortex activity was decoded into real-time spinal stimulation patterns.
• Closed-loop stimulation was compared to control periods without stimulation.

Main Results:

• Spinal cord stimulation controlled by cortical activity improved grasp-related electromyogram signals.
• Movement amplitude and task success rate were enhanced during closed-loop stimulation.
• Single motor unit activity from weakly active muscles successfully controlled stimulation in some sessions.

Conclusions:

• This study represents the first use of a neural prosthesis to improve primate hand function after motor cortex disruption.
• Closed-loop cortical control of spinal cord stimulation can reanimate paralyzed limbs.
• The findings demonstrate a potential therapeutic strategy for restoring limb function after neurological injury.