The elevated zero maze is a widely used scientific tool in neuroscience, specifically designed for assessing anxiety-like behaviors in rodents. It represents an advancement over the traditional elevated plus maze, having been developed to improve the accuracy and interpretation of results in behavioral studies. This apparatus provides a controlled environment to observe how rodents react to threatening open spaces versus safe, enclosed areas, offering insights into anxiety-related responses.
Understanding the Maze’s Design
The elevated zero maze is a ring-shaped runway elevated approximately 50 to 70 centimeters off the ground. This continuous track is divided into four equal sections, with alternating open and closed quadrants. Two opposite quadrants are enclosed by dark, high walls, around 30 centimeters tall, creating a sheltered space. The other two quadrants are open and exposed, bordered only by a small rim. This design leverages rodents’ natural aversion to open, elevated spaces and their preference for dark, enclosed areas.
How Anxiety is Measured
Anxiety-like behaviors in the elevated zero maze are quantified by observing the rodent’s tendency to avoid open, exposed areas. Less time spent in open quadrants and more time in enclosed sections indicates higher anxiety-like behavior. Researchers record the total time an animal spends in open versus closed quadrants, and the number of entries into each area. Other specific behaviors are also monitored, such as head dips over the edge of the platform, stretched attend postures (an elongated posture indicating cautious exploration), and rearing (standing on hind legs). Head dips and rearing suggest exploratory behavior, while stretched attend postures are associated with cautious risk assessment.
Refining Behavioral Research
The elevated zero maze demonstrates advantages over its predecessor, the elevated plus maze. It eliminates the central platform, which in the plus maze could lead to ambiguous interpretations as animals spent time in a neutral zone. The continuous, ring-shaped design of the zero maze encourages more fluid exploration and can reduce “freezing” behavior, where an animal becomes immobile. This continuous movement provides a more consistent measure of anxiety-like responses across trials. The maze also shows the effects of both anxiety-reducing (anxiolytic) and anxiety-increasing (anxiogenic) drugs; for instance, anxiolytic drugs like diazepam increase the time rodents spend in open areas, while anxiogenic substances decrease it.
Interpreting Test Outcomes
Data collected from the elevated zero maze are analyzed to draw conclusions about anxiety levels by comparing experimental groups to control groups. Researchers use video tracking systems or infrared photocells to record the animal’s movements and time spent in each section. Statistical methods analyze variables including the percentage of time in open quadrants, latency to enter an open quadrant, and the frequency of specific behaviors like head dips or stretched attend postures. A higher percentage of time in open arms or increased entries into these areas in an experimental group compared to controls suggests a reduction in anxiety-like behavior. These findings contribute to understanding the neurobiology of anxiety disorders and aid in the testing and development of therapeutic agents.