They have developed a ready-for-the-clinic brain prosthetic to help people with memory problems. The broad target market includes people with Alzheimer’s and other forms of dementia, as well as those who have suffered a stroke or traumatic brain injury. Surgeons will one day implant Kernel’s tiny device in their patients’ brains—specifically in the brain region called the hippocampus. There, the device’s electrodes will electrically stimulate certain neurons to help them do their job—turning incoming information about the world into long-term memories.
In Berger’s approach, electrodes in the hippocampus first record electrical signals from certain neurons as they learn something new and encode the memory. These electrical signals are the result of neurons “firing” in specific patterns. Berger studied how electrical signals associated with learning are translated into signals associated with storing that information in long-term memory. Then his lab built mathematical models that take any input (learning) signal, and produce the proper output (memory) signal.
Theodore Berger and his colleagues at the University of Southern California in Los Angeles have developed a working hippocampal prosthesis that passed the live tissue test in 2004. In 2011, in collaboration with Drs. Sam A. Deadwyler and Robert E. Hampson at Wake Forest Baptist Medical Center, a proof-of-concept hippocampal prosthesis was successfully tested in live rats. The prosthesis is in the form of multisite electrodes positioned to record from both the input and output “sides” of the damaged hippocampus, the input is gathered and analyzed by external computation chips, an appropriate feedback is computed, then used to stimulate the appropriate output pattern in the brain so that the prosthesis functions like a real hippocampus. In 2012, the team of Berger, Deadwyler and Hampson tested a further implementation in Macaques prefrontal cortex, further developing the neural prosthesis technology. In 2013, Hampson et al. successfully tested a hippocampal prosthesis on non-human primates. While the device does not yet consist of a fully implantable “chip,” these tests, from rat to monkey, demonstrate the effectiveness of the device as a neural prosthetic, and the labs plan to begin human trials in a few years.
PBS Nova provides an update on the Berger and Kahana brain memory enhancing prosthetic work in 2015.
When the team watched and didn’t activate the device, the rats performed the trial correctly 80% of the time. But when they switched on the device that provided the proper CA1 signal, the accuracy rate jumped to 95%. They also found that they could interfere with the memory, too, by stimulating the CA1 neurons with an incorrect signal. Then, accuracy dropped to 75%, according to results published in the Journal of Neural Engineering.
The Kernel team is starting to sketch out prototypes of the device and is conducting tests with epilepsy patients in hospitals. They hope to start a clinical trial, but first they have to figure out how to make the device portable. (Right now, patients who use it are hooked up to a computer.)
Berger says that in rats, the researchers did detect a “significant common code,” but that they couldn’t find one in their primate experiments. However, he adds, they studied far fewer primates, so they didn’t have as big a dataset to analyze. As for humans, “even if there is a generalized memory code, it’s going to be tough to find it using the tools we have right now,” Berger says.
The problem is that humans have way more neurons than rats; we have about 86 billion, while rats have about 200 million. So electrodes placed in the human hippocampus will record from a much smaller percentage of the neurons there. “Our information will be biased based on the neurons we’re able to record from,” Berger says. One of Kernel’s goals will therefore be to develop implants with denser arrays of electrodes that can record from more neurons.
Funding for Kernel was from Bryan Johnson. Johnson sold his payments company, Braintree, to PayPal for $800 million in 2013.
Joohnson then set up a $100 million fund that invests in science and technology start-ups that could “radically improve quality of life.” The fund, which comes exclusively from his personal fortune, was called OS Fund, because he wanted to support companies that were making changes at the operating-system level, he said. Johnson’s goal was to take projects from “crazy to viable” — including start-ups attempting to mine asteroids for precious metals and water, delivery drones for developing countries, and an artificial-intelligence company building the world’s largest human genetic database.
SOURCES- Washington Post, Kernel, Spectrum IEEE, PBS Nova