Scientists know little about how the brain assigns cells to participate in encoding and storing memories.
Now a UCLA/University of Toronto team has discovered that a protein called CREB controls the odds of a neuron playing a role in memory formation. The April 20 edition of Science reports the findings, which suggest a new approach for preserving memory in people suffering from Alzheimer's or other brain injury.
"Making a memory is not a conscious act," explained Alcino Silva, principal investigator and a professor of neurobiology and psychiatry at the David Geffen School of Medicine at UCLA. "Learning triggers a cascade of chemicals in the brain that influence which memories are kept and which are lost.
"Earlier studies have linked the CREB protein to keeping memories stable," added Silva, a member of the UCLA Brain Research Institute. "We suspected it also played a key role in channeling memories to brain cells that are ready to store them."
Silva and his colleagues used a mouse model to evaluate their hypothesis. They implanted CREB into a virus, which they introduced into some of the cells in the animal's amygdala, a brain region critical to emotional memory.
Next they tested the mouse's ability to recall a specific cage it had visited before. The cage was outfitted with patterned walls and a unique smell.
To visualize which brain cells stored the mouse's memories about the cage, the scientists tracked a genetic marker that reveals recent neuron activity. When the team examined the animals' amygdalas after the experiment, they found substantial amounts of CREB and the marker in neurons.