Elevated plus maze

Elevated Plus Maze

The Elevated Plus Maze (EPM) is a widely used behavioral test in neuroscience and pharmacology research, particularly in the study of anxiety and anxiolytic drugs. The EPM is a plus-shaped apparatus with two open arms and two enclosed arms, elevated above the ground. It exploits the natural aversion of rodents to open spaces to measure anxiety-like behavior.

Design

The EPM consists of a plus-shaped platform with two open arms and two enclosed arms, typically elevated 50-70 cm above the ground. The arms are usually 30-50 cm long and 5-10 cm wide. The enclosed arms have walls around 15-20 cm high. The maze is usually made of plastic or metal and is often colored black or white to contrast with the rodent's fur color.

Procedure

In a typical EPM test, a rodent is placed in the center of the maze facing one of the enclosed arms. The rodent is then allowed to explore the maze freely for a set period, usually 5-10 minutes. The rodent's behavior is recorded, either manually or using automated tracking software. The main measures of anxiety-like behavior are the proportion of time spent in the open arms and the number of entries into the open arms.

Interpretation

Rodents naturally prefer enclosed spaces, so spending more time in the open arms is interpreted as decreased anxiety-like behavior. Conversely, spending less time in the open arms is interpreted as increased anxiety-like behavior. The EPM is sensitive to both genetic and environmental factors that influence anxiety, as well as to the effects of anxiolytic and anxiogenic drugs.

Limitations

While the EPM is a widely used and validated measure of anxiety-like behavior, it has several limitations. These include the potential for confounding effects of locomotor activity and the one-trial nature of the test, which limits its ability to measure changes in anxiety over time.

See also

• Open field (animal test)
• Light-dark box
• Novel object recognition test
• Morris water maze