First Direct Visualization Of Memory Formation In Brain

Ruzanna Harutyunyan's picture
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UCLA and McGill University researchers have, for the first time, "photographed" a memory in the making. The study clarifies one of the ways in which connections in the brain between nerve cells, called synapses, can be changed with experience.

The phenomenon is called "synaptic plasticity," and is the foundation for how we learn and remember. As we learn, the memories are stored in changes in the strength and/or number of synaptic connections between nerve cells in our brain. Long-lasting changes in synaptic connections are required for long-term memories. This is the first study to use fluorescent imaging to directly visualize protein synthesis - the making of a memory - at individual synapses during learning-related synaptic plasticity.

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Understanding how synapses can change with experience is critical to understanding behavioral plasticity and to understanding diseases in which learning and experience-dependent behaviors are impaired. Such diseases include mental retardation and Alzheimer's disease and anxiety and mood disorders. It also can elucidate potential strategies for improving normal cognition and behavioral plasticity.

The researchers used sensory and motor neurons from the sea slug Aplysia Californica that can form connections in culture. The neurons were stimulated with serotonin, which strengthens the synapses, and allowed them to detect new protein synthesis using a "translational reporter," a fluorescent protein that can be easily detected and tracked.

This is the first study to directly visualize protein synthesis at individual synapses during a long-lasting form of synaptic plasticity. The studies revealed an exquisite level of control over the specificity of regulation of new protein synthesis. "While this was not really surprising to us given the complexity of information processing in the brain," said Martin, "visualizing the process of protein synthesis at individual synapses, and beginning to discern the elegance of its regulation, leaves us, as biologists, with a wonderful sense of awe."

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