Brown Institute for Brain Science

Forced Swim Test

Rationale of Test

This task is used to assess depressive-like behavior (or a form of learned helplessness). Animals that are considered more depressive tend to give up sooner and more completely when faced with a high degree of adversity.

Apparatus

A 2 Liter beaker is filled with 1500mL of room temperature water and placed in an isolation chamber. Water is changed between subjects. The isolation chamber is placed in front of a digital camera connected to a computer with a digitizer board and video tracking software.

Procedure

The forced swim test is carried out in an isolation chamber to eliminate external cues from influencing a mouse’s behavior. A single mouse is placed in the water filled beaker for a period of 5-minutes and their behavior is digitally recorded. The mouse’s behavior is analyzed offline to measure immobility (a measure of depressive like behavior) with the aid of digital tracking software. Mice are judged to be immobile when making no movements or only those movements necessary to keep its head above water.

Interpretation

In this task, more depressive animals give up and stop struggling sooner and more completely, whereas less depressive animals tend to swim vigorously and attempt to climb out of the cylinder for greater period of time.

Relevant Controls

Care should be taken to insure no differences between groups in motor function, motor coordination, motor endurance, and balance.

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