x
[quotes_form]

Time in the Open Arms: A Core Behavioral Measure in the Elevated Plus Maze

Learn More about our Services and how can we help you with your research!

The Ethological Foundation of Anxiety Testing

The Elevated Plus Maze (EPM) remains one of the most extensively validated and widely used paradigms in behavioral neuroscience to assess anxiety-like behavior in rodents. It harnesses the natural conflict between the rodent’s innate curiosity to explore and its evolutionary aversion to exposed, elevated spaces.

At the center of this behavioral assay lies one of its most revealing variables: Time Spent in the Open Arms. This metric provides a direct, quantifiable window into an animal’s risk assessment, affective state, and behavioral inhibition—key constructs in anxiety research.

Unlike simple locomotor assays, the EPM offers contextual decision-making under stress, with the open arms posing a dilemma between fear and curiosity. The duration an animal willingly remains in this aversive but novel area is a sensitive readout of emotional regulation, particularly under pharmacological or genetic manipulation.

Design Specifics: Why the Maze Matters

Conduct Science’s Elevated Plus Maze has been engineered with precision and reproducibility in mind, enabling consistent data generation across labs and studies. The standard EPM design consists of two open and two closed arms (each ~5 cm wide × 30 cm long), elevated ~50 cm above the floor, with a central platform (~5 × 5 cm).

Rodents are placed in the center zone facing an open or closed arm. As the session unfolds, tracking systems (such as ConductVision or ANY-maze) quantify:

  • Time spent in open vs. closed arms

  • Number of entries into each arm type

  • Latency to enter the open arm

  • Center zone dwell time and transitions

  • Velocity and freezing behavior

Each of these contributes to a behavioral profile that speaks to the animal’s anxiety state, exploratory motivation, and neurobehavioral flexibility.

The Science Behind Open Arm Exploration

Why do rodents avoid open arms?

Rodents, especially nocturnal species like mice and rats, evolved to avoid exposed areas that increase vulnerability to predators. The open arms of the EPM mimic elevated, open environments, thus serving as anxiogenic stimuli.

Therefore, time spent in these zones is inversely related to anxiety-like behavior. Animals displaying anxiolysis (reduced anxiety) will explore open arms more frequently and for longer durations.

Expanded Interpretive Framework: Not All Open-Arm Time is Equal

Metric Profile Interpretation
High open-arm time, high entries
Low anxiety, active exploration, increased risk-taking behavior
Low open-arm time, high closed-arm entries
Elevated anxiety, strong avoidance, exploration under restraint
High open-arm time, low entries
Slow, prolonged risk-taking or reduced vigilance (possibly sedated)
No open-arm entries
Severe anxiety, potential locomotor impairment or fear-induced freezing

This contextual framework is essential in parsing true anxiolytic responses from confounding factors such as hyperactivity, sedation, or sensorimotor impairment.

Neurobiology of Open Arm Behavior

Time in the open arms reflects the integrated output of multiple neural circuits:

  • Amygdala: Mediates fear and threat evaluation

  • Prefrontal Cortex: Regulates inhibition and executive function

  • Hippocampus: Encodes spatial memory and contextual cues

  • Locus coeruleus and raphe nuclei: Modulate arousal and serotonergic tone

Pharmacologically, benzodiazepines (e.g., diazepam), SSRIs, and endocannabinoid agonists have all been shown to increase open arm time, validating the EPM as a translational tool for anxiolytic drug screening.

Real-World Example: Testing a Novel Anxiolytic

Experimental Overview

Subjects: 24 adult male C57BL/6J mice
Conditions: 3 groups – Vehicle, Drug A (Low Dose), Drug A (High Dose)
Duration: 5-minute EPM exposure
Tracking: ConductVision at 30+ FPS, automated zone mapping

Results

Group Time in Open Arms (s) % of Total Duration Open Arm Entries
Vehicle
52.3 ± 8.1
17.4%
5.1 ± 1.3
Drug A – Low
91.7 ± 10.5
30.6%
8.9 ± 1.4
Drug A – High
112.5 ± 11.7
37.5%
10.2 ± 1.6

📊 Graphical Representation: Bar plot of time in open arms by treatment group.

Conclusion: Both treatment groups demonstrated increased open arm engagement, suggesting a dose-dependent anxiolytic effect of Drug A.

Methodological Recommendations

To ensure valid, reproducible results, researchers should adhere to:

  • Standardized lighting conditions (open arms at ~300–500 lux)

  • Acclimation periods before testing (30–60 mins in test room)

  • Consistent session lengths (typically 5 or 10 minutes)

  • Automated zone tracking (manual scoring is discouraged due to bias)

  • Control for estrous cycle in female subjects when applicable

For cross-paradigm studies, it’s best to run EPM alongside tests like the Light/Dark Box, Open Field, or Novelty-Suppressed Feeding to construct a comprehensive behavioral phenotype.

Why Choose Conduct Science for EPM Research?

Our Elevated Plus Maze system offers:

  • ✅ Durable and modular aluminum construction for longevity and easy cleaning

  • Species-specific configurations for both mice and rats

  • ✅ Seamless integration with ConductVision AI software for automated, accurate tracking

  • ✅ Customization support for center zone size, arm width, and lighting intensity

  • ✅ Real-time data output: distance, time per arm, velocity, freezing events

Additionally, our platform supports multi-maze configurations, enabling simultaneous testing of multiple animals in high-throughput settings.

Conclusion: Time in the Open Arms as a Window into Anxiety

In the realm of rodent behavioral testing, Time in the Open Arms is more than just a number—it’s a reflection of adaptive flexibility, emotional conflict, and decision-making under stress. Whether you’re screening compounds for psychiatric disorders, investigating neural circuitry, or examining the behavioral consequences of genetic mutations, this metric offers high sensitivity and interpretability.

With the right maze design and software tools, your lab can generate data that is robust, reproducible, and meaningful.

Ready to enhance your anxiety research toolkit?

References

  • Pellow, S., Chopin, P., File, S. E., & Briley, M. (1985). Validation of open:closed arm entries in an elevated plus maze as a measure of anxiety in the rat. Journal of Neuroscience Methods, 14(3), 149–167.
  • Walf, A. A., & Frye, C. A. (2007). The use of the elevated plus maze as an assay of anxiety-related behavior in rodents. Nature Protocols, 2(2), 322–328.
  • Carobrez, A. P., & Bertoglio, L. J. (2005). Ethological and temporal analyses of anxiety-like behavior: the elevated plus-maze model 20 years on. Neuroscience & Biobehavioral Reviews, 29(8), 1193–1205.

Written by researchers, for researchers — powered by Conduct Science.

Author:

Louise Corscadden, PhD

Dr Louise Corscadden acts as Conduct Science’s Director of Science and Development and Academic Technology Transfer. Her background is in genetics, microbiology, neuroscience, and climate chemistry.