Much as turning the television dial changes what comes into the living room, these brain cells are able to change what they allow in by swapping one kind of channel, or membrane opening, for another. Doing so lets the cells fine-tune their messages and adjust connections within the cerebellum, the brain region that controls fine motor skills.
Although the cells' channel-changing ability has been recognized for a few years, the key players controlling it hadn't been identified. Now, by studying mice, the Hopkins team has identified two proteins, called PICK1 and NSF for short, that help replace channels that let charged calcium ions in with another kind of channel that keeps calcium out. If muscle-controlling nerve cells can do the same thing, forcing the swap might help protect them from a calcium overdose that can kill them in Lou Gehrig's disease.
"We don't know yet whether this happens in muscle-controlling nerve cells, but we're looking into it," says Richard Huganir, Ph.D., professor of neuroscience and a Howard Hughes Medical Institute investigator in Johns Hopkins' Institute for Basic Biomedical Sciences.
So far, no one has really looked for the channel changing in other cells in the brain, he says, in part because the swapped channels are most common in these particular cells in the cerebellum (so-called stellate cells). But Huganir thinks the channel changing is going to be relatively common in the brain.
Whether through channel changing or other, more well-understood ways of fine-tuning its responsiveness, a brain cell's activity level depends on its neighbors, the nerves and other
Contact: Joanna Downer
Johns Hopkins Medical Institutions