The Use of the Puzzle Box as a Means of Assessing the Efficacy of Environmental Enrichment

The overall goal of the following experiment is to evaluate the efficacy of environmental enrichment on cognitive function in mice. This is achieved by first creating a puzzle box containing two chambers. Mice are then habituated to the testing arena and allowed to discover the entrance to the sheltered goal box.

Next, the mice are challenged with a variety of obstructions or puzzles blocking the shelter entrance. The results show that environmental enrichment reliably improves performance in the puzzle box. The key advantage of this technique over other methods is its ease and simplicity in both constructing the box as well as implementing, and the fact that it's, it is extremely flexible in designing tasks with different levels of cognitive load.

So this method can be used to address a range of questions in the field of neuroscience, particularly those associated with assessing the effectiveness of environmental interventions. Though this method can provide insight into the effect of environmental enrichment on cognition, it can also be applied to other systems such as genetically modified animal models of human disease and preclinical testing of novel therapeutics. To begin randomly assign pregnant mice to either standard housing conditions by placing them into a standard mouse cage or the enriched condition by placing them into rat sized cages.

Place a variety of objects designed to increase sensory and motor stimulation into the enrichment cage every two to three days. Move these objects around within the cage and refresh any that have been destroyed upon weaning sex, the pups, and segregate them into housing conditions consistent with the environment from which they were raised for the enriched condition. Ensure that there are between three and 10 mice per cage with two and five mice for the standard group.

Behavioral testing should begin once these animals reach adulthood. At 12 to 14 weeks, the puzzle box is constructed out of six pieces of white acrylic, a piece of black acrylic with a square opening cut into the side is placed 150 millimeters from one end to split the box into two compartments. A piece of white acrylic is placed over the smaller compartment to create a dark goal box.

The acrylic lid can be fixed to the body of the main box by hinges or left free to be completely removed during behavioral testing. Next, join three pieces of acrylic to make a U-shaped channel to be used as an obstruction during the testing that follows. First, thoroughly clean the puzzle box with 70%alcohol.

Repeat this step between testing each animal. Next place a clean red mouse, igloo within the goal box and replace the lid when ready. Place the mouse into the far end of the open field section facing towards the goal box.

Immediately start a timer and record the time it takes for the animal to enter the other chamber. Stop the timer. When all four paws of the animal enter the goal box section, terminate the trial.

If the animal does not enter the goal box within a preset time limit. After the trial, remove the animal and place it into a separate holding cage. Maintain a 60 to 182nd gap between trials for each animal.

Perform three trials per day for five consecutive days. Throughout the course of testing, introduce four obstruction conditions with three trials of each condition. First, introduce the U-shaped channel constructed earlier, and record the time it takes for the animal to enter the goal box to create another obstruction condition.

Place bedding within and around the channel before testing other obstructions that can be introduced. Include placing a tissue or foam plug within the doorway. The third trial of a given obstruction condition should always be administered on a subsequent day After testing is complete, calculate the time taken to complete each trial, including null trials where animals did not complete the task within the specified time.

Finally, use a repeated measures on NOVA to assess the effect of housing condition on performance within the puzzle box. This data represents puzzle box task performance of adult animals raised from birth in either enriched or standard environments. Animals raised in an enriched environment solved the obstruction tasks within the puzzle box significantly faster than those raised in a standard environment with peak differences occurring between the second and fourth days of testing.

When attempting this procedure, it is important to remember to handle your animals appropriately to prevent unexpected stress induced behaviors. So following this procedure, other methods such as immunohistochemistry, targeted surgical interventions or in vivo electrophysiology could be used to unravel the mechanisms under underlying the observed behavioral effects. So after watching this video, you should have a good understanding of how to obtain efficient and reliable preliminary assessment of cognitive function in AMAs model.