The Modified T-Maze is used to study learning, cognition and memory behavior in rodents. The conventional T-Maze is modified by slightly elevating one of the goal arms of the maze. The elevated goal is an open space and is an aversive arm, while the other goal arm is enclosed by walls to create a safe space. The Modified T-Maze allows the subject to choose between the arms by following its memory and exploratory traits. The Modified T-Maze can be used to study different exploration and decision-making tasks like the Spontaneous Alteration test and the Decision-Making test.

Stress can act as a triggering factor for varying psychological disorders and impaired behavioral responses in human as well as animals. Stress-based studies conducted on animal models such as rodents help in identifying the underlying mechanisms of the psychological disturbance and its relevant treatment. The Modified T-Maze can be used to evaluate neurochemical alterations, genetics, and environmental factors leading to pathophysiological conditions in stressed animals.

The Modified T-Maze is a T shaped apparatus having an elongated arm that serves as a start area and two goal arms. The goal arms contain goal boxes that are used for confining a subject during a trial. The subject can be forced to explore or given a free choice to select between the goal arms depending upon their cognitive response. Other apparatus used to explore memory, and cognitive behavior in rodents include the Y maze, the Novel Object Recognition Assay, the Radial Arm Maze, and the Automated T-Maze.

The Modified T-Maze is a T shaped acrylic chamber consisting of three equal size arms each 41.5 cm long and 6 cm wide. The apparatus is divided into two sections secure and insecure. The central arm and the right -side goal arm of the maze are designated as secure arms. These arms are covered from the top and consists of 6 cm high acrylic walls. The left goal arm is elevated and suspended above the floor. The arm is open from the top and consists of walls with holes and serves as the insecure arm. The central arm contains a starting box to confine the subjects. A goal box is also found at the ends of both goal arms. The dimension of each box is 7.5 x 6 x 6 cm. The boxes are equipped with sliding guillotine doors to control the movement of the subject between the arms.

Clean the apparatus thoroughly before starting the trial. Maintain the hygiene of the apparatus by removing any traces of urine or feces found during the trials to avoid any disturbance cues during the experiment. An external tracking and recording systems such as Noldus Ethovision XT can be used with the Modified T-Maze for observing the rodents’ behavior.

Forced Reference Trial

Confine the subject in the start box for 10 seconds. After 10 seconds, open the door of the box and let the subject enter the central arm of the maze. Close the path towards the left arm of the maze so that the subject can only move towards the secure arm (right goal arm). Observe the subject until it reaches the goal box in the secure arm of the maze. When the subject enters the goal box with all four paws inside, close the door. Keep it confined in the box for 5 sec.

Decision-Making Task

Confine the subject for 10 seconds in the start box after it is exposed to the reference trial procedure. After 10 seconds of confinement, open the door of the box and allow it to move towards the central arm. Keep the paths towards the right and left arm open. Terminate the trial after five minutes or when the subject makes its choices towards any of the arms.

Evaluation of the impact of CUMS in decision making

The purpose of the study conducted by Pardon, Perez-Diaz, Joubert, and Cohen-Salmon (2000) was to analyze the cognitive behavioral response of B6D2F1 female mice after the exposure of chronic ultra-mild stress (CUMS). The subjects were broadly classified into two groups, control and stressed. The stressed groups underwent a 1-week stress induction regime based on environmental and social stressors over a period of 8 weeks. Following the treatments, subjects were individually evaluated on the Modified T-Maze. Both groups showed a higher frequency of avoidance response in the Modified T-Maze task. In comparison to the controls, stressed groups showed a higher frequency of the alternation response. After the fourth week of CUMS, stressed animals showed random choice behavior. It was concluded that the stress affected the decision-making ability of the subjects by increasing the capacity of processing information in treated animals.

The following parameters can be observed in a Modified T-Maze:

• Frequency of visits to the insecure arm
• Frequency of visits to the secure arm
• Time spent in the start arm
• Time spent in the insecure arm
• Time spent in the secure arm
• Latency to initiate the task

Strengths

Modified T-Maze is a simple yet powerful apparatus to observe memory and learning traits in rodents.  It is easy to operate and produces reproducible results. It can be easily adjusted according to the experimental demands. Different protocols such as the spontaneous alternation task, reference memory task and discrimination task can be applied using the Modified T-Maze. Modifications in the T-Maze also allow display of more complex behavioral responses by the subjects. The Modified T-Maze allows straightforward and simple data analysis. The insecure arm of the maze challenges the exploratory drive of the subjects by providing a novel environment.

Limitations

Subject training is an important concern while using a Modified T-Maze for the assessment of cognitive behavior in rodents. Mishandling or overtraining may influence the task performances. Presence of unnecessary stimuli such as auditory, olfactory or visual, can affect the subject’s task performances. Subject’s explorative drive is also an important factor to obtain reliable results. Factors such as the age, gender, and strain, among others, may also contribute to the task behavior.

• The Modified T-Maze is used to study learning, cognition and memory behavior in rodents.
• The task performance in the Modified T-Maze is based on the subject’s memory and exploratory behavior.
• The maze provides the subject with a safe, walled secure arm and an open, elevated insecure arm.
• The Modified T-Maze can be effectively used to observe the pathophysiological conditions triggered by stress.
• The Modified T-Maze is easy to operate and highly adaptable for the needs of the different experimental model.
• Results obtained using the Modified T-Maze are dependent on subject handling and training.

1. Deacon, R., & Rawlins, N. P. (2007). T-Maze alternation in the rodent. Nature Protocol, 1(1), 7-12. doi: 10.1038/nprot2006.2
2. Pardon, M.-C., Perez-Diaz, F., Joubert, C., & Cohen-Salmon, C. (2000). Influence of a chronic ultra mild stress procedure on decision-making in mice. Journal of Psychiatry & Neuroscience, 25(2), 167-177.