Neuroscientists and engineers at Brown University in Providence developed a wireless broadband implanted brain sensor that the researchers are testing in lab animals. The team led by Brown engineering professor Arto Nurmikko described their findings at this week’s 2013 International Workshop on Clinical Brain-Neural Machine Interface Systems in Houston, and in the April 2013 issue of the Journal of Neural Engineering (available for 30 days with free registration).
Scientists at Brown and elsewhere are experimenting with wired systems that connect implanted brain sensors in humans to help people with severe paralysis use their thoughts to move robotic arms and other assistive devices, known as the BrainGate project. “This wireless system addresses a major need for the next step in providing a practical brain-computer interface,” says John Donoghue, who directs Brown’s Institute for Brain Science, where the research was conducted.
One part of the device is a chip about the size of a pill with electrodes implanted on the cortex. That chip sends signals through electrical connections to a sealed, titanium signal processing and power unit 56 x 42 x 9 millimeters (2.2 x 1.65 x 0.35 inches) containing the device’s battery, radio-frequency and infrared transmitters, copper recharging coil, and signal processing circuits. The developers say the processing and power unit resembles a sardine can with a port hole — the port hole being an electrically transparent sapphire window through which the radio and charging signals pass.
The device transmits data at 24 megabytes per second with 3.2 and 3.8 gigahertz microwave frequencies to an external receiver. After a two-hour wireless charge, the device can operate for more than six hours.
The researchers tested the device implanted in three pigs and three three rhesus macaque monkeys. The team has been safely recording data from the implanted devices in the animals for as long as 16 months. The researchers say data from these six devices demonstrate the ability to decode neural dynamics associated with motor activity.
One value of wireless systems is that they allow the implant recipients to take part in a wider range of realistic behaviors that neuroscientists can then connect to the brain signals received from the subjects. The new device is not approved for use in humans, nor do the researchers intend to test it in human clinical trials. However, the researchers conceived the device with the BrainGate project team that provided advice for eventual clinical applications.
The Brown team plans to advance the device to transmit more neural data, reduce its size, and improve its safety and reliability. Lead author David Borton, now a postdoctoral researcher at Ecole Polytechnique Federale in Switzerland, plans a collaboration with his former colleagues at Brown to study the role of the motor cortex in an animal model of Parkinson’s disease.
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