Triggering a Mouse's Happy Memories With Lasers Gives It the Will To Struggle On

the_newsbeagle writes: With optogenetics, scientists can tag neurons with light-responsive proteins, and then trigger those neurons to "turn on" with the pulse of a light. In the latest application, MIT researchers used light to turn on certain neurons in male mice's hippocampi that were associated with a happy memory (coming into contact with female mice!), and then tested whether that artificially activated memory changed the mice's reactions to a stressful situation (being hung by their tails). Mice who got jolted with the happy memory struggled to get free for longer than the control mice. This tail-suspension test was developed to screen potential antidepressant drugs: If a rodent struggles longer before giving up, it's considered less depressed.

Comments

less depressed or more insane?

[slew]

The tail suspension test (TST) was developed as a rodent screening test for potential (human) antidepressant drugs. It is based on the assumption that an animal will actively try to escape an aversive (stressful) stimulus. If escape is impossible, the animal will eventually stop trying ("give up"). In the TST a mouse is suspended by the tail so that its body dangles in the air, facing downward. The test lasts for six or more minutes and may be repeated multiple times. Mice initially struggle to face upward and climb to a solid surface. When the animal stops struggling and hangs immobile it is considered to have “given up”. Longer periods of immobility are characteristic of a depressive-like state. The validity of this test stems from the finding that treatment with an antidepressant drug will decrease the time the animal spends immobile.

I imagine if the drug made the mouse more insane (i.e., struggling more against the impossible). Conversely, I imagine if the drug made the mouse smart enough to know it was impossible, it would appear depressed.

Reminds me of a scene in the Bruce Lee film Enter The Dragon where he realizes he finds himself in a trap and just sits down and waits to make his move.