Dr. Grumpy, a very interesting neurologist, brings up a tale he found in The Journal of Experimental Biology, in which snails improved their memory by getting whacked out on amphetamines. Wait, what?
Apparently, snails can breathe in two ways. One, in high oxygen environments like air, they can absorb enough oxygen through their skin. Should they have to crawl through a low-oxygen pond, they can also extend breathing tubes to the surface, like a snorkel. This principle was used to get the snails to crawl through a meth-pond, getting the snail totally high. Probably to verify effects in human users of such drugs.
Human users of meth experience distortions of memory, remembering more strongly traumatic things that happened during drug binges, and tend to follow habits obsessively. The scientists were curious as to if this were cultural or biological, and so tried to test it on snails, which have no culture.
Snails in deoxygenated ponds tend to bring up a breathing tube. However, it can "hold its breath" if this proves unwieldy. So they had snails crawl through ponds, and poked the snail in a way that annoyed it every time the snail tried to open a breathing tube. Some of the ponds were just low oxygen, but others were full of meth.
Sure enough, snails that crawled through ordinary ponds didn't remember the previous ones, and got poked. Snails that crawled through meth ponds tended to remember the previous pond, and held their breath.
This may be yet another reason why amphetamines are addictive drugs -- they reinforce existing obsessive-compulsive behaviors, one of which is obtaining and using amphetamines.