In 1998, Andy Clark and David Chalmers proposed that a computer operates together with our brains as an “extended mind,” potentially offering additional processing capabilities as we work out problems, as well as an annex for our memories containing information, images, and so on. Now a professor of biomedical engineering at the University of Southern California, Theodore Berger, is working to bring to market human memory enhancement in the form of a prosthetic implanted in the brain. He’s already testing it attached to humans.

The prosthetic, which Berger has been working on for ten years, can function as an artificial hippocampus, the area in the brain associated with memory and spatial navigation.

Hippocampus

Hippocampus (LIFE SCIENCE DATABASES)

The plan is for the device to convert short-term memory into long-term memory and potentially store it as the hippocampus does. His research has been encouraging so far.

Berger began by teaching a rabbit to associate an audio tone with a puff of air administered to the rabbit’s face, causing it to blink. Electrodes attached to the rabbit allowed Berger to observe patterns of activity firing off in the rabbit’s hippocampus. Berger refers to these patterns as a “space-time code” representing where the neurons are in the rabbit’s brain at a specific moment. Berger watched them evolving as the rabbit learned to associate the tone and puff of air. He told Wired, “As the space-time code propagates into the different layers of the hippocampus, it’s gradually changed into a different space-time code.” Eventually, the tone alone was enough for the hippocampus to produce a recallable space-time code based on the latest incoming version to make the rabbit blink.

The manner in which the hippocampus was processing the rabbit’s memory and producing a recallable space-time code became predictable enough to Berger that he was able to develop a mathematical model representing the process.

Berger then built an artificial rat hippocampus — his experimental prosthesis —to test his observations and model. By training rats to press a lever with electrodes monitoring their hippocampuses, Berger was able to acquire the corresponding space-time codes. Running that code through his mathematical model and sending it back to the rats’ brains, his system was validated as the rats successfully pressed their levers. “They recall the correct code as if they’ve created it themselves. Now we’re putting the memory back into the brain,” Berger reports. 

It’s maybe the this last statement that’s so intriguing. Does the brain have some kind of master memory index? Has it somehow integrated the artificial hippocampus’s memories into the rats’ directory? Will it also happen in humans?

Dustin Tyler, a professor of engineering at Case Western Reserve University, cautioned Wired, “All of these prosthetics interfacing with the brain have one fundamental challenge. There are billions of neurons in the brain and trillions of connections between them that make them all work together. Trying to find technology that will go into that mass of neurons and be able to connect with them on a reasonably high-resolution level is tricky.”

Still, Bergen himself is optimistic, telling IEEE Spectrum, “We’re testing it in humans now, and getting good initial results. We’re going to go forward with the goal of commercializing this prosthesis.”

What he envisions bringing to market based on his research is a brain prosthetic for people with memory problems. The tiny device would be implanted in the patient’s own hippocampus from where it would stimulate the neurons responsible for turning short-term memories into long-term memories. He hopes it can help patients suffering from Alzheimer’s, other forms of dementia, stroke victims and people whose brains have been injured.

prosthetic

(TED BERGER) 

Berger’s business partner in this is tech entrepreneur Bryan Johnson. After selling his payment gateway Braintree to PayPal for $800, he started a venture capital fund, the OS Fund. Its web site states its mission: “The OS Fund invests in entrepreneurs working towards quantum-leap discoveries that promise to rewrite the operating systems of life.” Johnson sees Berger’s work as one such discovery, and formed kernel to support it, running the company himself with Berger as the company’s Chief Science Officer.

(KERNEL)

Rats and monkeys — the prosthetic improved the memories of rhesus monkeys attached to their prefrontal cortex — are one thing. The greater number of neurons in human brains is a big issue that needs to be grappled before Berger’s implant will work well for humans: It’s difficult to gain a comprehensive view of what’s going on with larger brains due to their greater number of neurons. (Rat brains have about 200 million neurons; humans have 86 billion.) Berger warns, “Our information will be biased based on the neurons we’re able to record from,” and he looks forward to tools that can capture broader swaths of data going forward. It’s anticipated that they’ll need to pack a greater number of electrodes into prostheses.

Human trials so far have been with in-patient epileptics with electrodes already in place for their epilepsy treatments. Berger’s team has observed and recorded activity in the hippocampus during memory tests, and they’ve been encouragingly successful at enhancing patients’ memories by stimulating neurons there. kernel will be funding additional human trials.