Lab humans

Remember those mice on Mount Everest?

There may be a good reason for them to limit their mountain-climbing expeditions. It might shrink their brains.

Scientists have studied human mountain climbers and found reduced volume and density of white and gray matter in areas of the brain associated with motor activity.

It is not known if this phenomenon is relevant to mouse health, but it suggests that mice should use caution when participating in high-altitude activities.

Going to the happy place

You can train a mouse to stress out on cue by having it associate a particular sound with an unpleasant experience, like a mild electric shock. A group of researchers at Columbia University did the opposite. They taught mice "learned safety" by having training them to associate a sound with the LACK of an electric shock.

Then they put the mice in the water and let them swim around. After a couple of minutes, mice usually stop moving around, apparently in despair, having lost the will to live. At least that's how scientists interpret that behavior.

As reported here (Here's the paper), mice trained in "learned safety" can regain their will to live when they hear their "happy sound" and they start swimming again. Apparently, mice can be trained to overcome depression.

And their brains showed some of the same biological changes seen in mice given antidepressant drugs.

Does this mouse have a happy place?

Feathered mice

Because of its geographical isolation, New Zealand has a unique population of native animals. Until fossil evidence showed otherwise in 2006, it was believed that there were no mammals native to New Zealand that did not swim (marine mammals) or fly (bats).

No mice.

But there was an ecological niche that, in the rest of the world, was occupied by mice. In New Zealand, that niche was occupied by the flightless Stephen's Island wren (Xenicus lyalli). Its Latin name is taken from the lighthouse keeper who first described it scientifically, David Lyall.

The wren became extinct in 1894. Legend has it that David Lyall's cat, Tibbles, was single-handedly (single-pawedly) responsible for the demise of the Stephen's Island wren. It is more likely that the wren was hunted to extinction by feral cats or rats introduced to New Zealand by human settlers.

And who arrived to occupy that now-empty niche? Immigrant mice.