Sunday, February 26, 2012

Memory relies on a balance of old and new

In the brain, there are various structures involved with the generation of memories. What Japanese scientists found is that there are also variations in cells and their functionality when it comes to memory formation. It appears that age determines how the brain cell functions, which is rather peculiar. The study increases our understanding of creating and holding on to memories, which is in turn beneficial for studies regarding how to prevent or treat dementia.

To maintain the memory functionality of our brain, various tasks need to be carried out. What the Japanese scientists found is that neural cells created by young stem cells are required to form new memories, while older stem cells generate neurons required for holding on to them. Experiments were performed in mice, and the researchers found a way to shut down either old or young cells, in order to discover what happens to memory processes in the brain. The memory neurons of young and old age are found in a brain area called the dentate gyrus, which has already been implied in memory formation.

Mice were given tasks that required their brain to look at patterns which involved the use of memory. During a pattern separation test, the brain ought to compare events with each other. That means an event currently happening, for example, is compared with something that happened before, and the brain is supposed to tell the difference. During this process, new memories are formed so that the differences can be recorded. During the pattern completion test, however, the brain is supposed to retrieve a memory based on just a few clues. For this, only currently existing memories are used.

MIT scientists found that pattern separation was not possible without the presence of young neurons. On the other hand, pattern completion proved to be impossible without the older neurons. That means the brain associates different functions to cells of different age. It is peculiar that the brain does not create different forms of neurons, but rather uses age as a determining factor for whether a memory cell is involved with generation or holding on to memories.

In addition to an interesting brain process, it could help us to unravel the causes for various neurodegenerative diseases that affect memory formation or retrieval. It can also help us to find out how ageing affects the formation of memory. As stem cells grow older, it may explain why memory formation for old people is harder than for those who are young. 

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