[WilTimSon]

Ethical horrors aside, I'm a bit confused by their definition of depression here. I think there's a solid gap between 'constantly exposed to predators and thus feeling like there's no chance you'll survive' and 'feeling like life is just a black void of emptiness'. The latter being a very, very rudimentary description of depression that I've heard from friends.

Is there a scientist in the thread who could clear up why a mouse's will to persevere and live is equated with how depressed it is? Do mice just not perceive circumstance as well?

[mattkrause]

That description of the experiment isn’t correct. They’re not using predator calls or anything to induce depression.

Instead, the readout is how long the mouse spends scrambling to escape vs. floating immobile in the water, usually after a “training run” that demonstrates to it that it can’t escape. You can draw some vague parallel to “coping with adversity”, but the test’s value is mostly that historically, it has predicted drugs that seem to help human patients with depression: mice receiving anti-depressants tend to spend less time immobile.

[WilTimSon]

Ah, okay, that makes sense, thank you for clearing up my confusion. Basically, they're looking for the most effective substances to boost activity, which is one of the things that anti-depressants are supposed to help with.

[mattkrause]

It’s more that substances boosting activity also help with depression: nobody really knows the causal direction, or even if there really is one.

That said, one way to botch these assays is to do something that just directly increases locomotion. They did look at that in Table 1 though.