THE FORCED SWIM TEST

The FST task is used as a measure of behavioral despair. When rats are forced to swim in a closed space from which they cannot escape, they will eventually stop attempting to escape and become immobile (except from small movements in order to keep their heads above the water). The immobility reflects a state of despair and depression. Adapted from Porsolt (1978), in this task the rats will be individually placed in a vertical cylinder (height: 40 cm; diameter: 18cm) containing 15 cm of water maintained at 25 °C. Twenty-four hours later, the rats will be placed in the cylinder and during a five minute testing period, the time spent immobile will be measured. The rat will be considered immobile whenever it remains floating passively in the water in a slightly hunched but upright position, with its head just above the water surface. This task will be carried after the completion of RAWM testing.