Jaideep Mavoori, a University of Washington researcher, spends a lot of time thinking about communications—not telephone or radio, but the sophisticated network that is the human body's nervous system. He's most interested in helping people, afflicted by injury or disease, rebuild their ability to control voluntary body movements. "We want to help people get back at least some of what they've lost," he says.
The brain acts like a central processor for the body's nervous system. Neurons in the brain's motor cortex send signals through the spinal cord to control the contraction of specific muscles. When this pathway is disrupted by something like an accident or stroke, patients can lose the ability to voluntarily move their arms, legs, and other body parts.
After reading research that suggested the brain's nerve signals can be harnessed to create changes within itself and help it find new communications pathways, Mavoori and his University of Washington co-researchers, Andrew Jackson and Eberhard Fetz, developed a chip that could help people restructure their brains to restore lost physical abilities.
The researchers used physiology, biophysics, and electrical engineering to develop a circuit that could enable the brain to establish new motor cortex nerve connections. The tiny self-contained device, incorporating a processor chip, senses neural activity in real time and then converts the data into a stimulus that can be sent to another area of the brain (see the figure). The brain then remaps its internal processes and creates a new pathway it can use to compensate for impaired pathways.
The researchers placed the external prototype on top of the heads of several monkeys. When the device continuously connected neighboring brain sites into the motor cortex, it produced long-lasting positive changes. Specifically, the movements at the stimulation site changed to resemble the signals drawn from the recording site.
Mavoori says the best explanation for the change is a strengthening of pathways within the motor cortex from the recording to the simulation site. "This strengthening may be developed by the device's continuous synchronization of activity between the two sites," he says.
The prototype uses a tiny lithium-ion battery. But Mavoori believes that once the circuitry is condensed into an implantable chip, it may be possible for the technology to scavenge energy from the body itself. "It could be by using temperature differences or energy from movement," he says.