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

Summary

Environmental enrichment provides a potential protective effect against neurodegenerative disorders. Currently, however, there is no easy way of determining the efficacy of enrichment procedures. This protocol describes a simple “Puzzle Box” method for assessing an animal’s cognitive function, in order to reveal the effectiveness of environmental enrichment.

Abstract

Environmental enrichment can dramatically influence the development and function of neural circuits. Further, enrichment has been shown to successfully delay the onset of symptoms in models of Huntington’s disease ^1-4, suggesting environmental factors can evoke a neuroprotective effect against the progressive, cellular level damage observed in neurodegenerative disorders. The ways in which an animal can be environmentally enriched, however, can vary considerably. Further, there is no straightforward manner in which the effects of environmental enrichment can be assessed: most methods require either fairly complicated behavioral paradigms and/or postmortem anatomical/physiological analyses. This protocol describes the use of a simple and inexpensive behavioral assay, the Puzzle Box ^5-7 as a robust means of determining the efficacy of increased social, sensory and motor stimulation on mice compared to cohorts raised in standard laboratory conditions. This simple problem solving task takes advantage of a rodent’s innate desire to avoid open enclosures by seeking shelter. Cognitive ability is assessed by adding increasingly complex impediments to the shelter’s entrance. The time a given subject takes to successfully remove the obstructions and enter the shelter serves as the primary metric for task performance. This method could provide a reliable means of rapidly assessing the efficacy of different enrichment protocols on cognitive function, thus paving the way for systematically determining the role specific environmental factors play in delaying the onset of neurodevelopmental and neurodegenerative disease.

Introduction

Environmental enrichment (EE) may be defined as surroundings that provide animals with increased opportunity for social interaction, motor activity, and greater sensory stimulation than usually experienced in a standard laboratory environment.EE has been shown to consistently affect the behavior of animals, bringing about changes such as reduction of stress and anxiety-related activity ^8-10, improved performance in learning and memory tasks ^8,11, early onset of motor coordination and exploratory activity ¹¹, changes in maternal care ⁸ as well as resistance to addictive substances ^12-15. Further, EE has been reveal....

Protocol

Ethics statement: All procedures were approved by the Animal Ethics Committee of the University of Sydney and conformed to National Health and Medical Research Council of Australia guidelines. Procedures were performed on C57/BL6J mice which were reared at the University of Sydney Bosch Rodent Facility. All mice were housed in a single adequately-ventilated room in 21 °C ambient temperature on a 12 hr light-dark cycle with lights on at 0600 hr in individually ventilated cages with ad libitum access to dry food and water. Late-pregnancy females were randomly assigned to standard or environmentally enriched housing conditions.

1. Housi....

Results

The results described here are a representative sample, with data taken from several cohorts consisting of different litters. All behavioral testing was conducted between 0700 and 1100 hr, with randomized testing order of animals within a cohort. Animals raised in an enriched environment (n = 14, 7 female and 7 male) took significantly less time to solve the obstruction tasks within the Puzzle Box than those raised within a standard environment (n = 15, 7 female and 8 male) (see Figure 3) (Repeated measu.......

Discussion

The data presented demonstrate that the Puzzle Box can be used effectively to assess the impact of EE. Mice raised in enriched environments consistently took significantly less time to solve obstruction puzzles within this behavioral assay than did animals raised within standard laboratory conditions. Moreover, this difference was most prominent in the first trial for three of the four conditions tested, suggesting EE has a greater influence on an animal’s native problem-solving ability, relative to their capacity .......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Black Acrylic Board			280 x 250 mm with a 40 x 40 mm "door" cut into one side
White Acrylic Board			280 x 250 mm
White Acrylic Board			280 x 250 mm
White Acrylic Board			750 x 250 mm
White Acrylic Board			750 x 250 mm
White Acrylic Board			150 x 280 mm
White Acrylic Board
Underpass			3 pieces of 40 x 120 mm plexiglass or acrylic
Note: If unable to access acrylic board, plexiglass or similar non-porous material will suffice.
Webcam	Logitech	C210	Fix to roof with electrical tape. Alternatively, use a tripod.
VirtualDub v1.10.4	VirtualDub	N/A	Software for recording behaviour videos. Input from webcam.
TopScan v 3.0	CleverSys Inc.	N/A	Software for automated top-view tracking and analysis of mouse behaviour. Captured videos are analysed post-hoc.