MICHIGAN, NETRALNEWS.COM - For decades, scientists have scratched their chins over how we make and store memories that can be retrieved years later. The answer may finally have been reached.
A group of US and Japanese researchers say an experiment using mice has shown that the brain “doubles up” by simultaneously making two memories of events.
The phenomenon, which researchers believe is similar to the function of human brains, goes against the long-held assumption that all memories start as short-term within the hippocamus, before being slowly converted into long-term memories and “banked” in the cortex region.
That theory became famous in the 1950s after the case of Henry Molaison, whose hippocampus was damaged during epilepsy surgery and he was no longer able to make new memories, but ones from before the operation were still there.
The team at the Riken-MIT Center for Neural Circuit Genetics believe they have shown that the memory bank theory is not the case – and it could lead scientists to rethink some of the popular models of how memories are captured and stored. It could also lead toward a better understanding of diseases such as Alzheimer’s. The study is published in the journal Science.
Professor Susumu Tonegawa , the senior author on the paper, said he and his fellow researchers were able to watch how memories were stored in both regions of the brain. “This paper tells us in more detail how this cooperation between the dual systems . . . actually takes place.”
After watching specific memories form as a cluster of connected brain cells in reaction to a mild electric shock, the team used light beamed into the brain to control the activity of individual neurons – they could literally switch memories on or off.
The results showed that memories were formed simultaneously in the hippocampus and the cortex.
Professor Tonegawa, the director of the research centre, said: “This was surprising. This is contrary to the popular hypothesis that has been held for decades. “This is a significant advance compared to previous knowledge, it’s a big shift.”
Dr Amy Milton, who researches memory at Cambridge University, called the study as “beautiful, elegant and extremely impressive."