Scientists decipher the formation of lasting memories

Researchers at Karolinska Institutet have discovered a mechanism that controls the brain's ability to create lasting memories. In experiments on genetically manipulated mice, they were able to switch on and off the animals' ability to form lasting memories by adding a substance to their drinking water. The findings, which are published in the scientific journal PNAS, are of potential significance to the future treatment of Alzheimer's and stroke. "We are constantly being swamped with sensory impression," says Professor Lars Olson, who led the study. "After a while, the brain must decide what's to be stored long term. It's this mechanism for how the connections between nerve fibers are altered so as to store selected memories that we've been able to describe." The ability to convert new sensory impressions into lasting memories in the brain is the basis for all learning. Much is known about the first steps of this process, those that lead to memories lasting a few hours, whereby altered signalling between neurons causes a series of chemical changes in the connections between nerve fibers, called synapses.