Behavioral sciences. An animal model used to measure depressive-like behavior.
The rat or mouse is placed into a glass cylinder filled with water. The water depth allows the animal only to swim or float without their hindlimbs touching the bottom of the tank. In the beginning the animal tries to find an exit by swimming or diving. If it has no success it makes only the minimum movements to stay afloat and to keep the head over the water surface. When immobility occurs the animal is rescued. On the next day the animal is again placed in the water tank, and within a minute it remains again in the state of immobility. This behavior is called depression-like behavior.
During the experiments the different types of movements as swimming, climbing, jumping, diving, or immobility are observed. The forced swim test is used for example to study the effects of antidepressants.