Researchers at the Montreal Neurological Institute and Hospital, a research and instruction department of McGill University in Montreal, say that they were able to capture the very first image ever taken of a mechanism that underlies the formation of long-term memories. Their finding is the first visual proof that when the mind forms a new memory, new proteins are produced at the synapses between nerve cells in the brain. This "protein translation" process increases the strength of the connection and thereby reinforces individual memories.
At a molecular level, there are two properties related to memory that researchers must take into account. The first is stability, because more information is being maintained for a long time. Second, the memory system must be very flexible, to allow for adaptation and continued learning. Most research to date has focused on the synapses between cells, which are the primary site of storage and exchange of information, in the brain. Synapses form a tremendous, constantly changing network of connections. Their ability to adapt to change, which is called synaptic plasticity, is likely to be the fundamental concept behind memory and learning, according to researchers.
However, if this network of connections is constantly undergoing changes, then how are memories formed in the first place and how are they retained? Scientists have known for a long time that one of the most important steps in the formation of long-term memories is the creation of new proteins at a synapse - called "translation" - which strengthens the synaptic connection related to the reinforcing of a memory. Until now, it has been only a theory and has not been actually imaged.
Researchers with the McGill study used a translational reporter, which is a fluorescent protein, easy to detect and track, as it moves through the brain. They were able to visualize the increase in local translation - protein synthesis - during the formation of a memory. The translation they viewed was specific to synapses, and it depended on the cell being able to receive a signal, coming from across the synapse. Therefore, this communication required that the pre- and post-synaptic parts of the neurons, be able to communicate with each other. The resulting image proved that local translation, that is highly regulated, occurs at the synapses during plasticity.
Synaptic plasticity and long-term memory, require certain changes to the activity of genes, according to researchers, and they can occur in a manner that is specific to certain synapses. This study offered solid evidence that the mechanism operating behind this gene activation that takes place during neuronal plasticity is related to the translation of controlled protein at the synapses. These findings are exciting and important because they can offer insight into the disease processes of chronic ailments that involve memory impairment.
The ability to learn, and the ability to create new memories and retain them is critical to the daily existence and personal identity of most human beings. Thanks to this groundbreaking study, scientists are one step closer to learning how to help people retain the memories of a lifetime as they grow older.