Scientists from the Gladstone Institutes in California (United States) have deciphered how a protein called Arc is involved in the formation of lasting memories. The finding is published in the magazineNature Neuroscience. Previous studies had revealed that Arc was involved in thelong term memory, since when a mouse lacked the protein it was able to learn new tasks but did not remember them the next day.
The new work, led by researcher Steve Finkbeiner, professor of Neurology and Physiology at the University of California, has delved into the inner workings of synapses – the highly specialized junctions that process and transmit information between neurons. Most of the synapses in our brain are not created during early brain development, but can form, break, and strengthen throughout our lives. Thesynapses that are more active get stronger, a process that is essential for storing new memories.
In laboratory experiments, first in animal models and then in Petri dishes, scientists tracked Arc movements and found that when individual neurons are stimulated during learning,Arc begins to accumulate in the synapses, but immediately afterwards it moves to the nucleus of the neuron. “A closer look revealed three regions within the Arc protein that direct its movements: one exports Arc from a nucleus, another transports it to the nucleus, and a third keeps it there,” explains Erica Korb, co-author of the study. That this system is so complex and tightly regulated shows that the process is biologically important.
In fact, the team’s experiments revealed that Arc acted as a master regulator of the entire homeostatic scaling process – that is, the mechanism that allows individual neurons to strengthen new synaptic connections that have enabled memories to form while protecting neurons from too much excitement (which could cause epileptic seizures). During memory formation, certain genes must be turned on and off at very specific times in order to generate the proteins that help neurons establish new memories. From inside the core, the authors found that it is Arc who directs this process and allows learning to translate into long-term memory .
Scientists recently discovered that Arc is depleted in the hippocampus or brain memory center in Alzheimer’s patients. Arc production and transport dysfunctions can also be an important element in autism .
