Because it penetrates the tissue, the Utah group can cause inflammation and scarring around the implant site, which leads to a decrease in signal quality over time. And the quality of the signals is important because it affects the performance of the BCI. No one knows how long Utah’s weapons last in the brain; so far the record is held by Nathan Copeland, whose device is now in its eighth year.
Placement in the Utah group also requires doctors to perform a craniotomy, making a small hole in the skull. It is a serious procedure that can cause infection and bleeding, and recovery takes a month or more. Understandably, many patients are reluctant to receive it, even if it means they can talk or walk again.
Precision is trying to solve all these problems with a device that has 1,024 electrodes but is ultrathin – about one-fifth the thickness of a human hair – and does not pierce the brain. Instead of a craniotomy, it is placed using a minimally invasive procedure that involves making a small incision in the skin and skull, then placing the implant in the outermost part of the brain, called the cortex. “The very idea of seriously damaging a brain or nervous system that is already damaged is very difficult,” says Rapoport, who also co-founded Neuralink. They think improving the process could make these procedures more attractive to patients.
Craig Mermel, the company’s president and chief product officer, says the Precision team can easily be reissued. As BCI technology advances, patients who receive early brain chips may also want to upgrade to new ones. With Utah arrays, new devices often cannot be installed in the same location due to the scar.
With more than 1,000 electrodes, Mermel says, the Precision device will be able to provide a higher level of information about brain activity than currently available. Precision models are also designed to be modular. Many can be connected together to collect brain signals from a large area. For specific or complex tasks beyond strengthening basic movements or activating computer functions, “you’re going to want to expand the brain regions,” says Mermel.
Peter Brunner, associate professor of neurosurgery and biomedical engineering at Washington University in St. Louis. Louis, says the Precision implant looks impressive, but there is still uncertainty as to how long it will last. Any implanted device tends to degrade over time. “There’s a trade-off between making things small and still maintaining energy versus the environment these devices are exposed to in the human body,” he says.
The brain changes in the skull, and so does the implant, says Brunner. Visuals can circulate more than what enters the brain. They say that even a micrometer change can change the group of neurons that the device is recording, which could affect how BCI works.
Rapoport says all electrodes move slowly over time, but Precision’s software, which detects neural signals, can pick up on those small changes.