A Molecular Signal of Cognitive Decline

Scientists are on the verge of discovering the specifics about genetic effects age has on memory-loss. German neuroscientist Andre Fischer and his colleagues are conducting a study using old and young mice. They test the mice's memory by fixing chambers with shockers and other obstacles. They hypothesized that the aging of the mice cause the histones to associate with the DNA differently, causing modified gene expression. After the mice had been trained for an hour in the chamber, over 2000 genes in the hippocampus became more active in the younger mice compared to only six in the older mice. The reason for the staggering results seems to be that younger mice undergo acetylation at a specific spot on the histone protein (H4K12).

In order to test if indeed the acetylation is the cause of the memory enhancement, a drug was administered to the older mice to help restore the acetylation effects in the hippocampus. The result was similar gene expression to the younger mice AND an increased memory of the shock locations of the chamber.

I thought it was interesting how researchers can tell a mouse has memorized a shock placement in the chamber. When a mouse sees the familiar location of a shock, they do a "fearful freezing behavior" and hesitate before they continue through the chamber. Hopefully someday the information gained from these experiments can be applied to drugs that thwart dementia and other cognitive difficulties associated with old age.