Brain-Computer Interfaces
| Neuroengineers at Brown University have developed a fully implantable and rechargeable wireless brain sensor capable of relaying real-time broadband signals from up to 100 neurons in freely moving subjects. Several copies of the novel low-power device have been performing well in animal models for more than year, a first in brain-computer interface research. |
The researchers' wireless BCI allows the user to move freely, dramatically increasing the quantity and quality of data that can be gathered — instead of watching what happens when a monkey moves its arm, scientists can now analyze its brain activity during complex activity, such as foraging or social interaction.
The benefit of using wireless communication transfer is obvious once the wireless implant is approved for human testing.
Arto Nurmikko, professor of engineering at Brown University who oversaw the device’s invention, recently presented his team's work at the 2013 International Workshop on Clinical Brain-Machine Interface Systems in Houston.
“This has features that are somewhat akin to a cell phone, except the conversation that is being sent out is the brain talking wirelessly,” Nurmikko said.
Neuroscientists can use such a device to observe, record, and analyze the signals emitted by scores of neurons in particular parts of the animal model’s brain.
Wired systems using similar implantable sensing electrodes are being investigated in brain-computer interface research to assess the feasibility of people with severe paralysis moving assisted devices like robotic arms or computer cursors by thinking about moving their arms and hands.
This wireless system addresses a major need for the next step in providing a practical brain-computer interface,” said neuroscientist John Donoghue, the Wriston Professor of Neuroscience at Brown University and director of the Brown Institute for Brain Science.
The device, a pill-sized chip of electrodes implanted on the cortex sends signals through uniquely designed electrical connections into the device’s laser-welded, hermetically sealed titanium “can” measures 2.2 inches (56 mm) long, 1.65 inches (42 mm) wide, and 0.35 inches (9 mm) thick.
That small volume houses an entire signal processing system: a lithium ion battery, ultralow-power integrated circuits designed at Brown for signal processing and conversion, wireless radio and infrared transmitters, and a copper coil for recharging — a “brain radio.” All the wireless and charging signals pass through an electromagnetically transparent sapphire window.
“What makes the achievement discussed in this paper unique is how it integrated many individual innovations into a complete system with potential for neuroscientific gain greater than the sum of its parts,” David Borton, a former Brown graduate student and postdoctoral research associate who is now at Ecole Polytechnique Federale Lausanne in Switzerland said. “Most importantly, we show the first fully implanted neural interface microsystem operated wirelessly for more than 12 months in large animal models — a milestone for potential [human] clinical translation.”
After a two-hour charge, delivered wirelessly through the scalp via induction, the implant can operate for more than six hours.
“The device uses less than 100 milliwatts of power, a key figure of merit,” Nurmikko said.
The team worked closely with neurosurgeons to implant the device in three pigs and three rhesus macaque monkeys. The research in these six animals has been helping scientists better observe complex neural signals for as long as 16 months so far. In the new paper, the team shows some of the rich neural signals they have been able to record in the lab. Ultimately this could translate to significant advances that can also inform human neuroscience.
In the experiments in the new paper, the device is connected to one array of 100 cortical electrodes, the microscale individual neural listening posts, but the new device design allows for multiple arrays to be connected, Nurmikko said. That would allow scientists to observe ensembles of neurons in multiple related areas of a brain network.
“What makes the achievement discussed in this paper unique is how it integrated many individual innovations into a complete system with potential for neuroscientific gain greater than the sum of its parts,” David Borton, a former Brown graduate student and postdoctoral research associate who is now at Ecole Polytechnique Federale Lausanne in Switzerland said. “Most importantly, we show the first fully implanted neural interface microsystem operated wirelessly for more than 12 months in large animal models — a milestone for potential [human] clinical translation.”
After a two-hour charge, delivered wirelessly through the scalp via induction, the implant can operate for more than six hours.
“The device uses less than 100 milliwatts of power, a key figure of merit,” Nurmikko said.
The team worked closely with neurosurgeons to implant the device in three pigs and three rhesus macaque monkeys. The research in these six animals has been helping scientists better observe complex neural signals for as long as 16 months so far. In the new paper, the team shows some of the rich neural signals they have been able to record in the lab. Ultimately this could translate to significant advances that can also inform human neuroscience.
In the experiments in the new paper, the device is connected to one array of 100 cortical electrodes, the microscale individual neural listening posts, but the new device design allows for multiple arrays to be connected, Nurmikko said. That would allow scientists to observe ensembles of neurons in multiple related areas of a brain network.
“This was conceived very much in concert with the larger BrainGate team, including neurosurgeons and neurologists giving us advice as to what were appropriate strategies for eventual clinical applications,” said Nurmikko, who is also affiliated with the Brown Institute for Brain Science.
Borton is now spearheading the development of a collaboration between EPFL and Brown to use a version of the device to study the role of the motor cortex in an animal model of Parkinson’s disease.
Meanwhile the Brown team is continuing work on advancing the device for even larger amounts of neural data transmission, reducing its size even further, and improving other aspects of the device’s safety and reliability so that it can someday be considered for clinical application in people with movement disabilities.
SOURCE Brown University
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