Always a good bet in biology that the thing we think is "junk" or "passive" or "dumb" is doing much more, we just don't understand it yet.

the experiment on "giving up" is pretty cool:

>All the while, the researchers monitored neurons and astrocytes in the zebra fish’s brain using advanced whole-brain imaging techniques. As the fish fruitlessly fought the current, neurons that release norepinephrine fired; in response, calcium built up in astrocytes. The buildup paralleled the number of attempts the fish made to fight the current, as if the astrocytes were keeping track — until at some point they issued a stop signal, and the zebra fish gave up. When Ahrens’ team disabled the astrocytes using a laser, the fish never stopped swimming. And if the astrocytes were artificially activated, the fish stopped right away.