In Eternal Sunshine of the Spotless Mind, the characters underwent a scientific procedure that allowed them to erase their memory. But what if, instead of erasing the memory, you could restore it? One eminent neuroscientist has set himself this task.
Theodore Berger of the University of Southern California is developing a prosthesis that will be able to restore memory by replacing part of the hippocampus of the human brain. Berger described his development at the international congress "Global Future 2045", which was held in New York on June 15-16 this year. This device has already been successfully tested in rats and monkeys, and is currently being tested in humans.
Memory machine
The hippocampus is a structure located deep in the temporal lobe of the brain that transforms short-term memories into long-term ones. Epilepsy and other neurological disorders can damage the hippocampus, preventing a person from forming new memories.
The device, developed by Berger and his colleagues, could replace parts of a damaged hippocampus and even enhance the ability of a healthy one. A tiny chip with electrodes is implanted in the hippocampus and records signals that represent short-term memories; the signals are then sent to a computer, where they are mathematically converted into long-term memories; and then sent to a second set of electrodes, which stimulates another part of the hippocampus.
The purpose of the device is not to identify individual memories, but to study how they are transformed into long-term ones. “It's like rules for translation,” Berger explains, adding that memories are like words, and their mathematical transformation is like translation.
Berger's team tested the devices on rats trained on a simple memorization task. Each rat with an implant was placed in a chamber with two arms. First, she was shown one lever on one side, and the rat pressed it. After a short wait, two levers appeared on either side, and if the rat pressed the second lever, it received a gulp of water. Successful completion of this task required the rat to remember which lever it pressed first.
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To test the function of memory prostheses, the researchers injected some rats with a substance that disrupts the natural function of memory, and repeated the experiment with levers. The rats were still able to use leverage correctly - which meant they were still able to form new memories. In other words, the rat implants memorized information for them.
Interestingly, the scientists found that the prosthesis was able to improve memory function even in rats that were not chemically injected.
Berger's team found the devices were equally effective on monkeys. They are currently conducting research on patients with epilepsy. They haven't collected much data yet, Berger said, but he believes the test results will be excellent.
He adds that the biggest challenge is figuring out how to mathematically transform short-term memories into long-term ones, because you only have one attempt at doing it right.
According to Berger, the ability of the brain to adapt - that is, its plasticity - is of great importance for the effectiveness of the device in patients. "The person has more influence on the device than the device on the person," says the professor.
The ultimate goal of researchers is to create a device that can restore lost or enhance normal human memory. But the philosophical aspect of memory manipulation is huge: If people can control their memories, can they also change them?
How will such a transformation affect the people themselves? Can memories be decoded and used as evidence in court? And will people be able to erase their memories and replace them with completely different ones? Today these questions remain for the future.