Product Info

The elevated plus test is one of the most widely used tests for measuring anxiety-like behavior. The test is based on the natural aversion of mice for open and elevated areas, as well as on their natural spontaneous exploratory behavior in novel environments. This test has a strong validity profile for anxiolytic drug validation and screening. All open end arms include 1cm high end plates to ensure the mice do not fall off the maze during exploration.

Variation 2: a variation of the elevated plus maze is the elevated cross maze, which utilizes a clear central area with 4 door partitions.

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  1. Product Description
  2. Prices and Sizes
  3. Modifications Available
  4. Documentation
    4.1 Introduction
    4.2 Apparatus and Equipment
    4.3 Training Protocol
    4.4 Modifications
    4.5 Sample Data
    4.6 Strengths and Limitations
    4.7 Summary and Key Points
    4.8 References
  5. Product Blueprints
    5.1 Product Sizes
    5.2 Product Images
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Mouse

$ 1890

+ Shipping and Handling ( $200)

  • +$100 with Doors
  • Acrylic
  • No Odor
  • Matte finish for non reflective surfaces
  • Easy clean with 70% Ethanol

Rat

$ 1990

+ Shipping and Handling ($250)

  • +$100 with Doors
  • Acrylic
  • No Odor
  • Matte finish for non reflective surfaces
  • Easy clean with 70% Ethanol

 Modifications Available

Doors

Used for Mouse or Rat

Dimensions: N/A

Cost $100

Extra Wall Height

Used for Mouse

Dimensions: 40cm

Cost $125 (Add $50 for Shipping)

Extra Wall Height

 Used for Rat

Dimensions: 50cm

Cost $150 (Add $75 for Shipping)

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Introduction

The Elevated Plus Maze is a commonly used behavioral task in neuroscience for studying anxiety states in animals. The maze is based on a key survival strategy for rodents: that they generally prefer enclosed areas while avoiding open exposed areas. The maze presents the animal with four arms: two enclosed and two open, and will test the animal’s approach-avoid conflict. The maze is most commonly used to validate anxiolytic or anxiogenic effects of pharmacological compounds, drugs of abuse, and hormones (Walf & Frye 2007). It can also test the brain sites and mechanisms underlying anxiety-like behaviors (Walf & Frye 2007). Animals treated with compounds that reduce anxiety will be more willing to enter the open areas and will spend more time in the open areas than control animals.

The Elevated Plus Maze was first designed based on a series of experiments and observations performed by K. C. Montgomery in 1955 (Montgomery 1955). Several decades later, Handley and Mithani adapted these observations into an elevated maze in a plus-shape (Handley & Mithani 1984). The maze was validated for both rats and mice and proven sensitive to both anxiolytic and anxiogenic drugs in many studies in the late 1980s and early 1990s (Walf & Frye 2007). The Elevated Plus Maze remains a commonly used task for its simplicity and validity in assessing anxiety states of animals.

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The apparatus used for the Elevated Plus Maze consists of four arms arranged around a small central platform in a plus shape. Two opposite arms are enclosed with high walls and the remaining two arms are open and exposed. The length and width of each arm varies with whether mice, rats, or small primates will be tested, but generally range from 30-50 cm in length and 5-10 cm in width for rodents. The maze is supported by four legs, raising it off the floor or table. Small end plates on the open arms prevent animals from falling off while exploring. The walls of the maze can be either clear or black, and the floor of the maze should provide contrast with the color of the animals.

The level of light in the testing room can influence animal behavior in the maze. The lighting should be overhead to prevent shadows within the maze and should be consistent throughout the maze.

A mounted video camera is used to record the experiments from above the maze. Tracking software can be used to follow the moments of the animals within the maze. Live scoring can also be performed with a stopwatch.

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The purpose of the Elevated Plus Maze is to assess the anxiety state in animals by comparing a control group to a treatment group and observing their inclination to explore the open arms of the maze. Rodents will naturally tend to explore the enclosed arms where they feel safe while spending less time exploring the open exposed arms. The amount of time spent exploring the open arms provides information regarding the anxiety state of the animal. In animals treated with anxiolytic drugs, anxiety-like feelings are reduced, and the animal will spend more time in the open arms of the maze. In contrast, animals treated with anxiogenic drugs will experience heightened anxiety-like feelings and will spend less time in the open arms of the maze.

There is no pre-training required for this task or repeated trials. Instead, the animals placed in the unfamiliar maze only once.

Evaluation of Anxiety State Using the Elevated Plus Maze

Prepare the apparatus by cleaning it thoroughly. Bring the animals’ home cage into the testing room and allow an acclimation period if necessary. Begin the video recording and gently place the animal on the central platform facing one of the open arms. Make sure all animals are placed facing the same arm. Start a timer as soon as the animal is placed in the maze. Allow the animal to explore the maze for a pre-set amount of time, generally ranging from five to ten minutes. Record the number of arm entries into the open and closed arms, as well as time spent in each arm. An arm entry is counted when all four paws are within the arm. After the pre-set amount of time has elapsed, remove the animal from the maze and return it to its home cage. (Walf & Frye 2007, Komada et al. 2008)

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Since its original design, the Elevated Plus Maze has been adapted into several other maze types. The Zero Maze has a very similar design with both enclosed and open regions, but eliminates the central platform of the Elevated Plus Maze. Both of these mazes have been validated by the treatment of animals with anxiolytic drugs (Campos et al. 2013). The Cross Maze is another variation that contains a clear enclosed central area, with doors leading to each arm. In this maze, the ends of each arm are open and exposed, making each arm identical to the animal.

Many groups have also used the Elevated Plus Maze with a pre-exposure component. This means that the animals are introduced to the maze prior to the testing period and may be tested more than once over several days or weeks. Reportedly, animals exposed to the maze more than once exhibit test decay and altered behavior in the maze, such as decreased activity on the open arms. To avoid these effects, it is now common to perform the task with no pre-exposure to the maze. (Walf & Frye 2007, Campos et al. 2013)

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The data obtained from the Elevated Plus Maze generally consists of four main measures: the number of open arm entries, the number of closed arm entries, the total time spent on the open arms, and the total time spent on the closed arms. These totals can be obtained from the tracking software or by using a stopwatch and recording the animals live. Other anxiety-related measures may also be recorded, such as the number of head dips and grooming. This data is generally visualized by graphing the individual measures and then comparing across control and treatment groups of animals. If the animals are treated with anxiety-reducing drugs, the time spent in the open areas will be greater than the control animals, as shown in the example graph below.

Using graphs similar to these to compare total time spent on each arm and the number of entries into the open and closed arms allows for easy visualization of the effect of drug treatments on the anxiety state of the animals tested. The more anxiety-like feelings the animal is experiencing, the more reluctant it will be to explore the open areas of the maze. Treatments with specific drugs can decrease or increase these feelings in the animals. Generally cohorts of approximately 20 animals per group are sufficient to obtain p-values of <0.05 using ANOVA (Vorhees et al. 2011, Walf & Frye 2007).

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A major strength of the Elevated Plus Maze is its simplicity, both in terms of testing method and interpretation. Trials with many animals can be run quickly and the analysis is generally straightforward as measures can easily be compared across control and treatment groups. However, an issue arises when evaluating the time the animals spend on the central platform, either prior to entering an arm or between arm entries. There can be some ambiguity regarding how this time is represented and interpreted. The Zero Maze removes this central platform and can be an alternative to the Elevated Plus Maze for specific strains or treatments.

It is also important to remember that the Elevated Plus Maze examines emotions in animals that are comparative to feelings of anxiety in humans. However, this test is not an equivalent of the entire spectrum of human anxiety. It is evident that anxiolytic drugs are able to reduce anxiety-like behaviors in the animals in the maze, but there are other factors to consider that may play important roles in interpreting results, such as age, weight, sex, species, and strains of the animals tested.

Summary and Key Points

  • The Elevated Plus Maze is a commonly used maze that tests the anxiety state of animals
  • This task features enclosed and open areas, and records how the animal explores the different areas of the maze
  • Animals naturally prefer the enclosed areas of the maze, but are also driven to explore
  • Animals experiencing anxiety-like feelings will be more reluctant to explore the open arms of the maze, while those treated with anxiolytic drugs are more willing to explore the open arms

Mouse

Elevated Plus Maze Mouse 2

Mouse Elevated Plus Maze Size (CM)

  • Arm Length: 35cm
  • Arm Width: 5cm
  • Wall Height: 20cm
  • Stand Height: 61cm
  • Edge Bumper: 1cm

Rat

Elevated Plus Maze Rat
Elevated Plus Maze Rat

Rat Elevated Plus Maze Size (CM)

  • Arm Length: 50cm
  • Arm Width: 10cm
  • Wall Height: 30cm
  • Stand Height: 61cm
  • Edge Bumper: 1cm