Restoring arm movement via a single neuron

The activation of a single neuron in the motor cortex of the brain may be enough to help restore muscle activity in the arms of paralyzed patients with spinal cord injuries, according to research published in this week’s issue of Nature. The work has potential for the future treatment of spinal cord injury, stroke and other impairments affecting movement, and could lead to more natural prosthetic devices.

Using a brain–machine interface, Chet Moritz and colleagues at the University of Washington, Seattle, USA, re-routed motor cortex control signals from the brains of temporarily paralyzed monkeys directly to their muscles. By creating artificial pathways for the signals to pass down, muscles that lacked natural stimulation after paralysis regained a flow of electrical signals from the brain. The monkeys were then able to tense the muscles in the paralyzed arm—a first step towards producing more complicated goal-directed movements.

The team notes that a neuron previously not associated with movement could be ‘co-opted’ to assume a new control role. This has implications for future machines that interface with the brain, which have so far focused on exploiting populations of neurons. These machines are also an important tool for the study of brain injury and motor control.

The team concludes that further work may lead to “implantable devices that could help restore volitional movements to individuals living with paralysis.”