Researchers at Duke University Medical Center have found a cascade of signaling molecules in the brain that allows a usually very brief signal to last for tens of minutes. This provides the brain framework for stronger connections (synapses) that can summon a memory for a period of months or even years, says Ryohei Yasuda, Ph.D., assistant professor of neurobiology.

Long-term potentiation (LTP) — the long-lasting increase of signals across a connection between brain cells — underlies our ability to remember over time and to learn. The team used a 2-photon microscopy technique to visualize molecular signaling within single synapses undergoing LTP. This technique allowed the team to monitor molecular activity in single synapses while measuring the synapses for increase in their volume and strength of the connections.

They found that signaling molecules Rho and Cdc42, regulators of the actin cytoskeleton, are activated by CaMKII, and relay a CaMKII signal into signals lasting many minutes. These long-lasting signals are important for maintaining long-lasting plasticity of synapses — the ability of the brain to change during learning or memorization.

How synapses change their strength of connections could have a bearing on Alzheimer’s disease, autism, and mental retardation, says Yasuda.

Their work appears March 20 in the journal Nature.