The Morris Water T maze insert for the Morris Water Maze is made to fit the 4 foot, 5 foot, or 6 foot sizing for the MazeEngineers Morris Water Maze. Made of stainless steel inserts for maximum stability within a large fluid container, long term use and easy cleaning.
The T-Maze is a popular behavioral assay for assessing reference memory and working memory. The apparatus was used by Dember and Fowler in the late 1950s to study alternation behavior in animals. Another popular behavioral assay is the Morris Water Maze, developed by Richard G. Morris in 1984. Both tasks have their own set of unique advantages and disadvantages. Thus, a hybrid version, the Water T-Maze was created to combine the best elements of both the apparatuses.
The Water T-Maze (WTM) is an effective paradigm in determining perseverance that conventional methods fail to address. The WTM combines rapid learning and averseness of the water seen in the Morris Water Maze task with the simplicity of the T-Maze. Unlike with other tasks, the WTM does not require food deprivation. The Water T-Maze overcomes the difficulties in ascertaining perseverative behavior and is an easy to implement and a high-throughput and straightforward task.
The apparatus consists of a pool within which T-Maze inserts are placed. The pool is filled with just enough water such that the walls of the maze cannot be used by the subject to climb over. The choice arms of the maze are covered with Plexiglas to prevent the subject from climbing over once it has reached the escape platform.
The apparatus is composed of a circular pool of diameter 45 cm and a T-Maze constructed of aluminum placed within the pool. The arms of the T-Maze are 18.5 cm long and 5 cm wide. The escape platform measures 5 x 5 cm and is placed in one of the choice arms of the maze. The tops of the choice arms are covered with Plexiglas rectangles to prevent the subject from jumping out of the pool once it has reached the escape platform.
The pool is filled with 13 cm of water, and it is ensured that the platform is covered with 1 cm of water. The water is colored opaque. The temperature of the water is maintained at 23o C, and the apparatus is well-lit. The task is straightforward and can be manually scored, but a tracking and video software such as the Noldus Ethovision XT can also be used to assist with the scoring.
The pre-training of the subject involves placing the subject in the start arm and allowing it to explore the maze for 60 seconds freely. During the pre-training, an escape platform is not placed in either of the choice arms. The first arm entered by the subject is noted, and during the trials, the escape platform is placed under the opposite arm.
During the training period, if the subject failed to find the escape platform after 60 seconds, it is gently guided to the platform and allowed to rest on it for 10 seconds. After completion of the trials, the subjects are removed from the maze, dried and allowed 7 to 10 minutes between trials. Ten trials are conducted each day for four days.
Determination of position habit acquisition
After pre-training, the subject is placed on the start arm, and the escape platform is placed in the arm that was not chosen by the subject previously. The subjects are given 60 seconds to find the platform location, and on finding the platform, they are trained to stay on it for 5 seconds. In case the subjects do not find the platform at the expiration of 60 seconds, it is gently guided towards the platform and left to sit there for 10 seconds. Errors are recorded for each trial. The criterion is met if the subject chooses the correct arm in 8 out of the 10 trials per day over four consecutive test days. The subject is then trained for reversal positioning training (Guariglia and Chadman 2013).
Determination of reversal position learning
On fulfillment of the criterion for position habit acquisition, the subjects are trained in reversal position task. For this task, the position of the platform is changed to the opposite arm. The subjects are placed in the start arm and are expected to find the new position of the escape platform. In case the subjects do not find the platform at the expiration of 60 seconds, it is gently guided towards the platform and left to sit there for 10 seconds. Errors are recorded for each trial. On completion of 8 successful trials out of 10 training trials per day, the subject is marked as having met the criterion for that day (Guariglia and Chadman 2013).
The data collected from the task is based on the errors committed during the trials. For the training task, position acquisition and reversal learning, the following data is recorded:
In the reversal learning task, two observations can also be made:
Other data collection such as latency to find the platform, velocity, and other data specific to the investigation requirements can also be easily made. The data collected from the sessions can be visualized using graphs for ease of comparisons between groups or for analysis.
The below graph depicts a sample of perseverative and regressive errors made on Day 1, Trials 1–10 of reversal learning training. It is observed that the BTBR mice made a significantly greater number of perseverative errors and regressive errors on Day 1 as compared to B6 mice. (Guariglia and Chadman 2013)
Following is another graph plotting sample data for percentage of trials completed without error during position habit acquisition over 5 days of testing. (Guariglia and Chadman 2013)
Magnetoreception is a widely observed phenomenon across vertebrate classes, and the MWM plus maze is an undoubtedly necessary development in research on magnetically-influenced spatial behavior among rodents. Given the significance of the magnetic field as a global reference, it is highly unlikely that magnetic cues do not influence any directional or spatial behavior in some way (Phillips et al., 2013). Therefore, the MWM plus maze provides a means for understanding the extent of the impact that magnetic cues have on spatial orientation. Further, the apparatus can also shed light on previously unforeseen roles played by magnetic cues in rodent’s spatial behavior and cognition.
The apparatus’ design provides accurate manipulation of magnetic field alignments. The strict setup also ensures the absence of any alternative cues that may disrupt magnetoreception. Additionally, the method of electromagnetic shielding as a means of minimizing radio frequency interference also addresses any unexplained variability in past studies of magnetic compasses as used in spatial behavior. The simple and minimal training required for the MWM plus maze also serves to illustrate the robustness of the phenomenon of magnetoreception.
Morris, R. (1984). Developments of a water-maze procedure for studying spatial learning in the rat. Journal of neuroscience methods, 11(1), 47-60.
Phillips, J. B., Youmans, P. W., Muheim, R., Sloan, K. A., Landler, L., Painter, M. S., & Anderson, C. R. (2013). Rapid learning of magnetic compass direction by C57BL/6 mice in a 4-armed ‘plus’ water maze. PloS one, 8(8), e73112.
