The findings appear in the early online edition of the Proceedings of the National Academy of Sciences.
"This study presents strong evidence that a molecular process fundamental during development is retained in the adult and recycled in the service of memory formation," said Thomas J. Carew, Donald Bren Professor and chair of UCI's Department of Neurobiology and Behavior. "It is a striking example of how molecular rules employed in building a brain are often reused for different purposes throughout a lifetime."
The researchers have shown that proteins known as growth factors are as essential for the induction of long-term memory as they are for the development of the central nervous system. These growth factors, such as brain derived neurotrophic factor (BDNF), bind onto the brain cell through a specific type of receptor known as TrkB, much the same way a key fits into a lock. As an experimental strategy to determine the importance of BDNF-like growth factors in forming memories, the researchers used a "molecular trick" to keep the proteins from binding with the appropriate TrkB receptors.
For the experiment, the scientists used wild-caught Aplysia, a marine snail frequently studied in learning and memory because of its large brain cells. The Aplysia received a series of five tail shocks, spaced 15 minutes apart. The shocks cause the animals to exhibit heightened withdrawal reflexes days and weeks after the shocks are over.
When the animals are shocked, a brain chemical known as serotonin is released that promotes the formation of a long-term memory associated with the shocks. However,
Source:University of California - Irvine