One of humanity's most incredible abilities is being able to remember things that happened many years, perhaps even many decades ago. But it's only now that neuroscience is able to really explain how we can form such long-lasting memories.
Scientists have long suspected that the key to remembering things from long ago is what's known as long-term potentiation, or LTP. This basically involves a long-lasting increase in the signals sent along the connections between particular brain cells, which in turn allows us to keep recalling things we experienced decades after they first occurred. But what actually causes LTP had eluded scientists...until now.
Duke researchers have discovered a cascade of special molecules that make an otherwise very short-lived signal last for tens of minutes. That might not seem like a very long time, and yet that's the likely building block on which all our long-term memories rest. Over time, these minutes-long connections, or synapses, would be reinforced and strengthened into connections that can rest months, years, and even decades.
Lead researcher Ryohei Yasuda explains the team's findings:
"We found that a biochemical process that lasts a long time is what causes memory storage," said Yasuda, who is a Howard Hughes Medical Institute Early Career Scientist. The signaling molecules could help to rearrange the framework, and give more volume and strength to the synapses. We reasoned that a long-lasting memory could possibly come from changes in the building block assemblies."
Two of the crucial molecules in strengthening these connections - and, by extension, maintaining the long-term plasticity of the synapses and our continued ability to learn new things - are known as Rho and Cdc42. We already know that mental diseases including Alzheimer's disease are linked to abnormal signals from these molecules, and Yasuda is optimistic that this new research will help us understand more about the underpinnings of the conditions.