gum tree

when they use animals to test drugs
they often kindle (use electric or mircowave energy aimed at the animal's brain ) parts of neural tissue that when damaged cause
either emotional problem
cognitive problems
neuro degenrative diseases
or movement orders.
..

The behavioural despair test (or Porsolt forced swimming test) is a test, centered on a rodent's response to the threat of drowning, whose result has been interpreted as measuring susceptibility to negative mood. 

Animals are subjected to two trials during which they are forced to swim in an acrylic glass cylinder filled with water, and from which they cannot escape. The first trial lasts 15 minutes. Then, after 24-hours, a second trial is performed that lasts 5 minutes. The time that the test animal spends in the second trial without making any movements beyond those required to keep its head above water is measured. This immobility time is decreased by various types of antidepressants and also by electo shock.Another common variant of this behavioral test specifically used for mice is conducted only for one trial and lasts six minutes. Modern implementations of the test score swimming and climbing behaviours separately, because swimming behaviour has been shown to be increased by selective serotonin reuptake inhibitors, while climbing behaviour is increased by selective norepinephrine reuptake inhibitors such as desipramine and maprotiline.