Use it or loose it

New brain cells die without a job to do

When it comes to brainpower they say you either use it or lose it. Now a study in mice suggests that the survival of newly formed adult brain cells depends on the amount of input they receive.

Fred Gage of the Salk Institute for Biological Studies in La Jolla, California, and his colleagues infected genetically engineered mice with a virus that stops new brain cells from producing NMDA receptors - proteins that sit on the surface of brain cells and help them communicate with each other. The virus used infects only newly generated cells, leaving other cells untouched.

Infected cells that lacked NMDA receptors died sooner than their normal counterparts, suggesting that communication is essential for survival (Nature, DOI: 10.1038/nature05028).

To confirm this the researchers injected some of the virus-infected mice with a compound that blocks all NMDA receptors. They found this increased the survival rate of the brain cells infected by the virus, and lowered that of the normal, uninfected cells. Gage speculates that preventing any brain cell communication via NMDA receptors levels the playing field, giving all the brain cells an equal chance of survival - indirect evidence that activation of NMDA receptors affects the survival of brain cells.

Since the cells the team studied were in the hippocampus, a brain region involved in learning and memory, Gage suggests that the fate of brain cells generated there helps guide the formation of memories and skills.