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Scripps Florida Scientists Find a Defect Responsible for Memory Impairment in Aging

JUPITER, FL, March 3, 2015 – Everyone worries about losing their memory as they grow older—memory loss remains one of the most common complaints of the elderly. But the molecular reasons behind the processes remain unclear, particularly those associated with advancing age.

Now, scientists from the Florida campus of The Scripps Research Institute (TSRI) have discovered a mechanism that causes long-term memory loss due to age in Drosophila, the common fruit fly, a widely recognized substitute for human memory studies.

The new study, published recently in The Journal of Neuroscience, describes in detail the loss of connectivity between two sets of neurons that prevents the formation of long-term memory.

“We show how long-term memory is impaired with age in Drosophila,” said Ron Davis, a TSRI professor and chair of the Department of Neuroscience who led the study. “This isn’t due to any functional defects, but to connectivity problems between neurons.”

The most widely studied form of memory in fruit flies is memory of smell. When an odor is paired with a mild electric shock, the flies develop short-term memories that persist for around a half-hour, intermediate-term memory that lasts a few hours and long-term memory that persists for days.

Using real-time cellular imaging to monitor the changes in aged flies’ neuron activity before and after learning, Davis and his colleague Ayako Tonoki found structural connectivity defects between a set of neurons known as dorsal paired medial neurons and mushroom body neurons; these defects prevented long-term memories from forming.

Long-term memories require new synapses and new proteins to be formed—as compared to short-term memory, which is built from existing proteins.

“Now that we know long-term memory loss is a connection problem,” said Davis, “to improve memory we’re going to have to think of ways of rebuilding those connections.”

The study, “Aging Impairs Protein-Synthesis-Dependent Long-Term Memory in Drosophila,” was supported by the National Institutes of Health’s National Institute of Neurological Disorders and Stroke (grant R37 NS19904) and by the Japan Society for the Promotion of Science (KAKENHI Grants 25115703, 26115505 and 26830003). For more information on the study, see http://www.jneurosci.org/content/35/3/1173.short

About The Scripps Research Institute

The Scripps Research Institute (TSRI) is one of the world's largest independent, not-for-profit organizations focusing on research in the biomedical sciences. TSRI is internationally recognized for its contributions to science and health, including its role in laying the foundation for new treatments for cancer, rheumatoid arthritis, hemophilia, and other diseases. An institution that evolved from the Scripps Metabolic Clinic founded by philanthropist Ellen Browning Scripps in 1924, the institute now employs more than 2,500 people on its campuses in La Jolla, CA, and Jupiter, FL, where its renowned scientists—including two Nobel laureates and 20 members of the National Academy of Science, Engineering or Medicine—work toward their next discoveries. The institute's graduate program, which awards PhD degrees in biology and chemistry, ranks among the top ten of its kind in the nation. For more information, see www.scripps.edu.

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Professor Ronald Davis is chair of the Department of Neuroscience at The Scripps Research Institute’s Florida campus. (High-res image)


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