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When a person's hippocampus becomes damaged or has to be removed (sometimes it's the only way to treat severe epilepsy), it can rob him or her of the ability to store long-term memories. A person without a hippocampus can still recall several events for a short period of time after they happen, but these memories fade after about thirty seconds. (Interestingly, when people have their hippocampuses removed, they keep memories they formed before the operation, even though they can't store new ones.) In Alzheimer's, a degenerative disease without a known cure, people also lose the ability to store long-term memories. It's a tragic illness that afflicts an estimated 5.4 million people in the United States (about 500,000 in California alone) and costs the country $183 billion a year to treat, according to the Alzheimer's Association.
Berger's tireless efforts to recreate the function of the hippocampus proved to be worthwhile. Just last year, he was the lead author of an article published in the Journal of Neural Engineering that detailed the success of a neural prosthesis used to assume the function of the hippocampus in rats' brains. (His team also worked with scientists from Wake Forest University in the study.)
In the experiment, researchers chemically severed the connection between the two major internal divisions of the hippocampus, which interact with each other to create long-term memory. Then, they implanted a tiny silicon microchip that duplicated the pattern of interaction between the two subregions and had the rats learn tasks, like pressing one lever instead of another for a reward.
To measure the activity between the two subregions of the hippocampus, the team implanted a bipolar stimulation electrode in the stratum radiatum of one subregion, which measured neural signals as the rats learned tasks. When the electrical activity peaked, it meant the new memories were sent to the hippocampus for long-term storage. To further prove that the microchip was functioning as a real hippocampus would, researchers disabled the chip and the rats lost their ability to store long-term memories. When they reactivated the device, long-term memory capability returned.
"Flip the switch on, and the rats remember," Berger was quoted as saying in a PR Newswire article shortly after the study was completed. "Flip it off, and the rats forget."
Basically, the study showed that a damaged part of the brain can be replaced with a silicon part that acts the same way. But the device can't retrieve old memories; it can only store new ones on the microchip. It also relies on functional live tissue to teach it what it needs to know, so it couldn't be used to replace tissue that was already damaged.
Koene says that while this work is impressive, it doesn't mean that the chip stores meaningful memories. The cells, he says, aren't actually storing a long-term memory; instead, they're creating impermanent and shallow neural connections after an episode occurs.
There's still a lot of work to be done. But when Berger started talking about his plans to create a synthetic hippocampus, the scientific and philosophy communities never thought it would happen.
Gallant was one of his skeptics. "I thought this was just silly, that it would never work," he wrote in an email. "After all, no one had ever done this before. And there are lots of reasons to think that it is much, much easier to decode information from the brain than it is to encode new information and put it into the brain." But since reading the paper Berger and his team wrote, Gallant gives them major credit for accomplishing such a complicated feat. "What they have achieved is indeed quite impressive. I think that it is very, very cool."
Koene says that one of his biggest accomplishments is convincing prominent scientists, including Berger, to not only take whole brain emulation seriously, but to do so publicly. It's forward thinkers like this that move theory into reality, but like every major feat, it takes hard work and perseverance.
"When you really think about it, things still have to make sense the way they always have. Time goes on and you want to achieve certain things," said Koene. "To do them, you need to put the work in, and you don't sit around and wait for trends to happen."
Ultimately, however, Koene's main obstacle may not be his detractors or funding; instead, it may be the very thing he seeks to understand. Perhaps the main problem isn't that we don't comprehend what creates our identities, but that our most advanced tool — the human brain — isn't sophisticated enough to crack its own code.
Maybe the brain just isn't designed to understand itself in its entirety. But that doesn't mean Koene and other proponents of mind uploading will stop trying.
Editor's Note: The original version of this story got wrong the year Randal Koene was born; it was 1971. We also got wrong the year Koene co-founded CarbonCopies.org; it was 2010. This version has been corrected.
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