Columbia University Medical Center

Results Published In Neuron Shed New Insight On The Way Humans Maintain Long-Term Memories

Promise for Enhancing Human Memory Possible in Novel Work with Sea Snail

NEW YORK (Sept. 25, 2008) – New ways to enhance memory and, moreover, prevent one’s memory from slipping over time – either as a result of natural aging or the onset of diseases such as Alzheimer’s – are considered by many scientists to be one of the final frontiers of scientific exploration, much like space or the world’s oceans.

Turns out that a sea snail off the California coast is yielding new insight into the way memory works, and the possibilities that the little creature may hold for understanding and deepening human memory is the subject of a paper published in Neuron today by Columbia University Medical Center’s Craig Bailey, Maria Concetta Miniaci and Eric Kandel, who won a Nobel Prize in 2000 for his work with Aplysia californica, the giant marine snail.

One of the most fascinating questions in the study of learning and memory is identifying the cellular and molecular mechanisms that lead to the persistence of memory storage – our ability to remember events for extended periods, in some cases even for a lifetime. Since neurons communicate via chemical synapses, and because memories are believed to be stored within these synapses, elucidating the precise mechanisms that regulate this communication has been the focus of intense scientific investigation the world over.

The size of the Aplysia neuron makes it a good candidate for memory research. Credit: Spira, University of Jerusalem.
The brain of Aplysia, which compared to a mammalian brain, has fewer and larger cells, makes it easier for researchers to isolate simple behaviors and their underlying neural circuitry and thus to study how the synaptic connections between these cells are modified by learning and memory. Previous studies in Aplysia and mammals have found that the storage of long-term memories requires the activation of new gene expression, the synthesis of new proteins and is often accompanied by the growth of new synaptic connections.

Experimenting with specific synaptic connections between identified sensory and motor neurons in Aplysia, Drs. Kandel, Miniaci and Bailey have examined the time required for local protein synthesis at synapses involved in the creation and recall of new and old memories, dubbed long-term facilitation (LTF). The results of their study provide the most direct evidence to date that the stable maintenance of long-term memories requires a specific stabilization phase for the storage of long-term memory. In this phase, newly formed synapses can be disrupted and require sustained local protein synthesis to acquire the more stable properties of mature synapses necessary for the persistence of memory storage.

“The Aplysia system is an important model for dissecting the mechanisms that link formation of synapses with long-term memory,” Dr. Miniaci said.

Research into the snail, and the discovery of the role of protein synthesis in maintaining long-term memories, could allow clinicians to someday chemically strengthen the neuro-circuitry of humans so that memory loss, either as a result of aging, dementia or Alzheimer’s, is a rarer phenomenon among humans, the researchers said.

Eric Kandel, M.D., is a university professor of physiology and the Kavli Professor in the Department of Neuroscience at Columbia University. Maria Concetta Miniaci is a professor in the Department of Neuroscience, College of Physicians and Surgeons, Columbia University as well as in the Department of Experimental Pharmacology, University of Naples Federico II, Naples, Italy. Craig Bailey, Ph.D., is an Associate Professor in the Department of Neuroscience at Columbia University Medical Center.

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