The Modified Flex Maze is a variation of the Flex Maze, designed to learn spatial navigation and learning in rodents. 

The Modified Flex Maze from MazeEngineers is available for both mice and rats.

The Modified Flex Maze is designed to study spatial navigation and learning in rodents. The hippocampus is mainly involved in short-term memory and learning or memorizing spatial environments in rodents (Schoenfeld et al., 2020). The hippocampal place cells encode the spatial location through spatially localized firing fields (O’Keefe & Dostrovsky, 1971; Gupta et al., 2010). In addition to the hippocampus, the dentate gyrus, which is responsible for the continual addition of neurons throughout life, also contributes to rodent’s spatial navigation (Lieberwirth, Pan, Liu, Zhang, & Wang, 2016). Different Mazes such as the Moris Water Maze and the Contextual fear conditioning are currently used to learn spatial navigation and learning in rodents. However, they utilize aversive and stressful motivation to complete the task. The Modified Flex Maze helps study spatial navigation and learning in complex spatial environments through escape-motivated tasks in the absence of aversive and stress-inducing stimuli (Schoenfeld et al.,2020). 

The Modified Flex Maze is a variation of the conventional Flex Maze, consisting of a flexibly modifiable labyrinth. The maze has a detachable floor with surrounding walls. The internal walls are detachable and can be arranged to create different maze configurations. The subject is trained through multiple maze configurations in the presence of distinctive visual and olfactory cues and then learns to search for the reward. The Modified Flex Maze can measure allocentric navigation and long-term memory (Schoenfeld et al.,2020). It is very useful to study hippocampal disorder and neurological illnesses in rodents.  

Other apparatuses to learn spatial learning and memory in rodents include the Water Moris Maze, the T Maze, the Radial Arm Maze, and the Barnes Maze. 

The Modified Flex Maze is comprised of an open arena (1 m length × 1 m width) with outer walls (50 cm high). The Maze floor is removable and contains a grid (9 × 9) of high cylindrical pins (24 cm). The Modified Flex Maze is also provided with removable walls (8 cm-width × 24 cm height) that can be placed and fit in between the pins to create a labyrinth with several maze configurations in the interior of the same open arena. The Modified Flex Maze is made of acrylic. 

Properly clean the maze before each trial to avoid the influence of any lingering stimuli. Properly lit the maze. The Nodulus Ethovision XT can be used to assist with observations and recordings. 

Habituation 

Allow subjects to habituate to the maze environment. Place the subject at the start corner of the passage and allow it to follow the route to reach the food reward placed at the end of the route, but in the same corner where the subject starts. The subject has to navigate through the whole maze to reach the food reward. Conduct four trials daily for five consecutive days. 

Pretraining

Configure the maze such that it provides nine directional choice points to reach the food reward. Place an odor cue at the start of the maze’s passage and place visual cues above the maze on the wall. Conduct four trials daily with an intertrial interval of 1 hour for three consecutive days. On the 4th day, conduct two training trials. Conduct two probe trials on the 4th day, allowing the subject to start the trial from the corner other than the start or end corner. 

The Long-term memory task 

After one week of training, allow the subject to complete the maze with nine directional choice points to reach the reward with the same odor stimuli present in the start corner. Conduct one trial. 

• The subject’s latency to finish the Maze (sec)
• Total time taken to reach the reward
• The number of Maze intersections crossed by the subject
• The number of vicarious trial and error 

Investigation of the effect of neurogenesis deficiency on spatial learning and memory of rats

 Schoenfeld et al. (2020) investigated spatial learning and memory in neurogenesis deficient rats. The study comprised two groups: the TK rat group (n=7), in which the pharmacogenetic method was utilized to generate a loss of neurogenesis, and the control group (n=7). Both control and TK rats were tested for real-time behavior with peppermint present during various training and testing trials. A Mint odor test was also conducted in the Open Field.  The results of the study showed that in the cinnamon and banana scented maze tasks, both groups performed similarly during learning (p>0.05) and showed similar spatial knowledge when started from probe corners (p>0.05). They also showed similar long-term memory for the route (p>0.05). However, in the peppermint-scented maze task, controls were slower than the TK rat group during acquisition, and they took a long time to reach the reward from different start positions (p<0.05). They also showed lower performance after a delay (p<0.05).  The results of the open field task revealed that both groups avoided the corner presented with peppermint. They spent more time in the non-peppermint corners (p < .0001), which suggested peppermint odor as aversive and showed altered exploration of both groups. The study concluded that the loss of new neurons doesn’t impose any impact on rats’ spatial learning and memory; however, loss of new neurons distracts rats from completing the maze. 

Strengths 

The Modified Flex Maze task is easy to perform. The removable internal walls of the Modified Flex Maze allow various maze configurations. The surrounding walls prevent subjects from falling off the maze. The Modified Flex Maze is spatially complex compared to other mazes such as the T Maze, the Elevated Plus Maze, the Radial Arm Maze, the Morris Water Maze, or the Barnes Maze. The task performance is not difficult as subjects can learn to reach reward through efficient routes within 4-12 trials. 

Limitations 

The Modified Flex Maze requires pretraining of the subjects; therefore, it is time-consuming. The repeated handling may cause stress to the subjects. The presence of surrounding olfactory, visual, and auditory cues may alter task performance. The factors such as age, gender, the strain of the subject may influence observations. 

• • • The Modified Flex Maze is a variation of the Flex Maze, designed to learn spatial navigation and learning in rodents. 
    • It consists of an open arena with surrounding walls and a detachable floor. 
    • The Modified Flex Maze contains detachable walls inserted in the Maze to create a flexibly configurable labyrinth. 
    • The subject searches the food reward placed at one corner of the Maze with the help of olfactory and visual cues.  
    • The Modified Flex Maze requires pretraining of the subject. 
    • The Modified Flex Maze can be utilized to study the impact of neurological and hippocampal illnesses in rodents.