The playground maze: a new method for measuring directed exploration in the rat

Area of Science:

• Neuroscience
• Behavioral Science
• Pharmacology

Background:

• Assessing exploratory behavior is crucial for understanding cognitive function and the effects of psychoactive substances.
• Existing methods often involve high-stress environments or fail to differentiate between general activity and directed exploration.
• A need exists for a low-stress assay to specifically measure novelty-seeking behavior in rodents.

Purpose of the Study:

• To introduce and validate a novel behavioral test, the 'playground maze', for measuring exploratory responses to novelty in rats.
• To assess the utility of this test in differentiating the effects of psychoactive drugs on novelty exploration versus general locomotion.
• To investigate the preliminary effects of chlordiazepoxide and amphetamine on novelty responses and locomotion.

Main Methods:

• The 'playground maze' test involves exposing rats to a circular open field containing 7 familiar objects and 1 novel object.
• Exploratory responses were quantified by measuring the time spent in the vicinity of each object, expressed as a percentage of total exploration time.
• Locomotion was assessed by measuring the total path length traversed by the animals within the maze.
• Preliminary drug studies involved administering chlordiazepoxide (1-5 mg/kg) and amphetamine (1.5-4 mg/kg) and observing their effects on novelty response and locomotion.

Main Results:

• A novelty response was indicated by significantly more time spent exploring the novel object compared to the chance level (12.5%).
• Chlordiazepoxide (CDP) administration significantly increased the novelty response without affecting locomotion.
• Amphetamine at 4 mg/kg abolished the novelty response, while lower doses had no significant effect.
• All tested doses of amphetamine significantly increased locomotion.

Conclusions:

• The 'playground maze' is a valid and sensitive test for measuring exploratory responses to novelty under low-stress conditions.
• This assay effectively separates drug-induced changes in directed exploration (novelty response) from alterations in general locomotion.
• Preliminary findings suggest differential effects of chlordiazepoxide and amphetamine on novelty-seeking behavior and motor activity in rats.