Princeton scientists have discovered a key mechanism the brain uses to transfer short-term memories into permanent storage, a finding that could have broad implications for understanding how the brain maintains long-term stability.

Researchers led by neuroscientist Joe Tsien found that the brain appears to have a system of repeatedly replaying and reinforcing the same cellular event that led to the initial formation of a memory. The reinforcement is critical for creating the cell-to-cell connections that constitute long-term memories, the researchers found.

"It's really surprising to find out we need to reactivate this initial learning event," said Tsien. "It's like learning something again in your brain, only this time it's due to some kind of spontaneous reactivation mechanism."

This observation could yield insights into the much broader question of how the brain maintains a continuity of knowledge and memories over a lifetime despite the constant turnover of molecules and proteins.

The insight also may one day help with the understanding of human diseases such as schizophrenia, said Tsien. If the process of consolidating new experiences into long-term memories goes wrong, it could result in the incorrect association of a real memory with a mentally created experience, thereby leading to delusions, he said.

Tsien's study, published in the Nov. 10 issue of Science, also is interesting in its development of a cutting-edge genetic engineering technique that allowed him to control the function of a gene not only in a very specific region of the brain, but also at specific points in time. He created a strain of mice that had a modified version of a gene critical for memory formation. He constructed this gene so that it would stop functioning when the animals received a dose of the common antibiotic doxycycline in their drinking water. Taking the drug away restored the gene to its normal function.

The study focuses on a feature called the NMD
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Contact: Steven Schultz
sschultz@princeton.edu
609-258-3601
Princeton University
9-Nov-2000