The Elevated Plus Maze (EPM) is one of the most widely used and validated behavioral tests for assessing anxiety-like behaviors in rodents. Its ethological design mimics the natural conflict between an animal’s innate fear of open, elevated spaces and its drive to explore novel environments. While much attention is placed on time spent in the open arms as a measure of anxiolytic or anxiogenic responses, time spent in the closed arms is equally critical—it reflects avoidance behavior, stress response, and coping strategy.
Understanding closed-arm behavior provides researchers with insight into how an animal responds to a perceived threat. For rodents, enclosed spaces offer a sense of safety and protection. Therefore, increased time in the closed arms typically reflects a heightened anxiety state, while decreased time may indicate anxiolytic drug effects, behavioral disinhibition, or abnormal coping mechanisms.
At Conduct Science, we provide precision-built Elevated Plus Mazes designed for reproducibility and versatility. When paired with ConductVision AI tracking software or other compatible systems (e.g., ANY-maze), researchers can measure time in the closed arms with high temporal and spatial resolution, allowing for robust comparisons across genotypes, treatments, or stress models.
The duration a rodent spends in the closed arms can be influenced by several key variables:
Importantly, increased time in the closed arms doesn’t necessarily equate to a negative result. In some cases, it may indicate adaptive avoidance behavior under high-risk conditions. Conversely, reductions in closed-arm time without corresponding increases in exploratory behavior elsewhere (e.g., center or open arms) may point to locomotor suppression or impaired decision-making rather than true anxiolysis.
To demonstrate the application of closed-arm metrics, a study using Conduct Science’s Elevated Plus Maze examined the behavior of C57BL/6J mice under three treatment conditions:
| Group | Time in Closed Arms (s) | Time in Open Arms (s) | Total Entries | Movement Speed (cm/s) |
|---|---|---|---|---|
|
Control (Vehicle) |
210.3 ± 14.2 |
62.1 ± 8.9 |
16.8 ± 2.1 |
3.5 ± 0.4 |
|
Diazepam (1 mg/kg) |
145.7 ± 12.9 |
121.3 ± 10.6 |
22.4 ± 2.8 |
4.8 ± 0.5 |
|
SSRI (Chronic, 21 days) |
180.2 ± 13.5 |
89.6 ± 9.2 |
20.1 ± 2.4 |
4.2 ± 0.6 |
Here, diazepam-treated animals showed reduced time in the closed arms and increased exploration of the open arms—consistent with an anxiolytic effect. Chronic SSRI treatment resulted in a more moderate behavioral shift, aligning with the delayed onset of therapeutic action typical of this class of drugs.
Time in the closed arms is particularly informative when:
Moreover, this metric provides a robust baseline when paired with other parameters such as total arm entries, center time, and path trajectory. For example, high closed-arm time combined with low total entries may indicate sedation, while high closed-arm time with normal entry rates may reflect specific anxiety responses.
Our Elevated Plus Maze platform provides:
This allows researchers to automate the quantification of arm preference behavior, transition patterns, and time budgets with minimal observer bias.
Researchers can expand closed-arm data with physiological correlates:
By integrating behavioral data with neurophysiology, the EPM becomes a powerful platform for understanding the full landscape of anxiety disorders and treatment effects.
Time in the closed arms is not just a fallback measure—it is a core indicator of anxiety-related avoidance and behavioral inhibition. When properly interpreted, it can help distinguish between adaptive and maladaptive behavioral strategies, particularly in high-throughput screening studies and translational models.
Pellow, S., et al. (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.
Written by researchers, for researchers — powered by Conduct Science.
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.
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