Standard Rat EPM
50 × 10 cm arms · 40 cm walls · 50 cm elevation
Pellow 1985 canonical configuration. Used in over 6,000 published studies.
$2,495

Standardized behavioral assay apparatus for quantifying anxiety-like behavior in mice and rats through measurement of exploratory activity in open versus enclosed elevated arms.
| arm_configuration | Four arms at 90 degrees |
| arm_types | Two enclosed arms, two open arms |
| Automation Level | manual |
| Species | Mouse, Rat |
The Elevated Plus Maze (EPM) is a widely used behavioral assay for measuring anxiety-like behavior in laboratory rodents. The apparatus consists of four arms arranged in a plus configuration at 90 degrees, with two open arms and two enclosed arms elevated above the ground. This design exploits the natural conflict between rodents' innate exploratory drive and their aversion to open, elevated spaces.
Constructed from non-reflective matted acrylic, the maze is available in species-specific dimensions for mice and rats, with customizable features including door options, wall height modifications, and raised edge lips. The apparatus enables quantitative assessment of anxiety-related behaviors through measurement of time spent in open versus closed arms, arm entries, and ethological parameters such as risk assessment behaviors and locomotor activity patterns.
The elevated plus maze operates on the principle of approach-avoidance conflict, exploiting rodents' natural behavioral tendencies. Animals experience a conflict between their innate drive to explore novel environments and their aversion to open, elevated spaces that represent potential danger. The maze's elevation (61cm above ground) and open arm design create an anxiogenic environment that activates the animal's fear response system.
During testing, animals are placed in the central platform and allowed to freely explore all four arms for a defined period, typically 5-10 minutes. Anxiety-like behavior is quantified through multiple parameters including percentage of time spent in open arms, number of open arm entries, total arm entries (locomotor activity), and ethological measures such as stretch-attend postures, head dips, and defecation. Higher anxiety levels correlate with reduced open arm exploration and increased closed arm preference.
The non-reflective matted surface prevents visual artifacts that could influence behavior, while the ethanol-cleanable acrylic construction ensures consistent testing conditions between subjects. Optional modifications including doors, variable wall heights, and raised edge lips allow researchers to adjust the apparatus for specific experimental requirements and species-appropriate testing parameters.
| Feature | This Product | Typical Alternative | Advantage |
|---|---|---|---|
| Construction Material | Non-reflective matted acrylic with odor-resistant properties | Basic acrylic or painted wood surfaces that may retain odors | Prevents visual artifacts and maintains consistent olfactory conditions between test subjects |
| Dimensional Precision | Species-specific scaling with precise arm dimensions (mouse: 35cm length, rat: 50cm length) | One-size-fits-all designs with compromised scaling | Ensures appropriate anxiogenic stimulus strength for each species' natural behavioral patterns |
| Cleaning Compatibility | 70% ethanol resistant acrylic construction | Materials requiring specialized cleaning agents | Enables standard laboratory disinfection protocols for consistent experimental conditions |
| Modification Options | Doors, wall height extensions, raised edge lips, and specialized lighting configurations available | Fixed designs with limited customization | Allows protocol adaptation for specific research questions and safety requirements |
| Color Selection | Five color options (black, blue, clear, grey, white) | Single color offering | Enables optimization for different lighting conditions and video tracking contrast requirements |
This EPM provides species-specific dimensional scaling, non-reflective matted construction, and extensive modification options. The ethanol-compatible acrylic ensures consistent cleaning protocols while the modular design accommodates diverse experimental requirements from basic anxiety screening to specialized behavioral paradigms.
Verify arm dimensions and platform level using precision measuring tools before initial use and periodically thereafter.
Why: Dimensional accuracy affects the anxiogenic stimulus strength and behavioral measurement validity.
Inspect arm joints and support connections regularly, tightening hardware as needed to prevent movement during testing.
Why: Apparatus stability prevents vibrations that could influence animal behavior and measurement accuracy.
Habituate animals to the testing room environment for 30-60 minutes before EPM testing to minimize handling stress effects.
Why: Reduced stress from novel environments allows cleaner measurement of anxiety-specific behaviors rather than general stress responses.
Record both traditional parameters (time in open arms, entries) and ethological measures (stretch-attend postures, head dips) for comprehensive behavioral analysis.
Why: Ethological parameters provide additional sensitivity to detect subtle behavioral changes and validate anxiety-related interpretations.
If animals consistently avoid the central platform, reduce lighting intensity or check for vibrations from building systems.
Why: Environmental factors can overshadow the maze's anxiogenic properties and reduce the validity of behavioral measurements.
Consider raised edge lip modifications when testing animals with motor impairments or when conducting extended duration protocols.
Why: The 0.5-1cm safety barrier prevents falls while maintaining the open arm's anxiogenic properties for valid behavioral measurement.
Test animals during their active phase and maintain consistent timing across experimental groups.
Why: Circadian rhythms affect anxiety-related behaviors and locomotor activity levels in rodents.
Store the disassembled apparatus in a dry environment to prevent acrylic clouding and ensure longevity.
Why: Proper storage maintains the non-reflective surface properties essential for consistent behavioral testing conditions.
ConductScience provides a standard one-year manufacturer warranty covering defects in materials and workmanship, with technical support for apparatus setup and behavioral protocol guidance.
Background reading relevant to this product:
What is the Elevated Plus Maze?
The Elevated Plus Maze is a behavioral apparatus used to measure anxiety-like behavior in rodents. It consists of four arms arranged in a plus shape - two open and two enclosed - elevated above the floor.
How does the Elevated Plus Maze work?
Animals are placed at the junction of the four arms and allowed to freely explore. Anxious animals spend more time in enclosed arms, while less anxious animals venture into open arms. Time and entries in each arm type are recorded to quantify anxiety levels.
What research applications use the Elevated Plus Maze?
The Elevated Plus Maze is a gold-standard test for anxiolytic drug screening, anxiety disorder modeling, and stress research. It is used in pharmacology, behavioral neuroscience, and genetic studies of anxiety phenotypes.
Enhance your setup with compatible accessories
Use this apparatus with
Automate open and closed arm scoring, latency, and risk assessment with ConductVision behavioral tracking software.
ConductVision EPM →Step-by-step ConductMaze protocol with TTL events, parameter tables, and metric definitions.
ConductMaze EPM Protocol →Free calculator: enter open and closed arm times, get the open-arm duration ratio and 95% CI.
EPM Anxiety Index Tool →Choose your configuration
Pick the apparatus configuration that matches the cohort, species, and protocol. Species-specific adaptations should be interpreted within their own validation literature.
50 × 10 cm arms · 40 cm walls · 50 cm elevation
Pellow 1985 canonical configuration. Used in over 6,000 published studies.
$2,495
30 × 5 cm arms · 15 cm walls · 40 cm elevation
Scaled-down dimensions for mouse studies. Lister 1987 mouse adaptation.
$2,295
1 cm low ledge on open arms · same other dimensions
Preserves anxiolytic responsivity on retest. Bertoglio & Carobrez 2002.
$2,695
View mEPM →§ 1
The Elevated Plus Maze was introduced by Pellow et al. (1985) 1 as an unconditioned model of anxiety, building on earlier observations by Montgomery (1955) 2 that rats avoid open and elevated spaces. Pellow demonstrated that the open-arm avoidance response is reversed by classical anxiolytic compounds and exaggerated by anxiogenic challenges, establishing pharmacological validity for the paradigm.
Within a decade the EPM became the most widely-used anxiety screen in preclinical neuroscience. By 2010, over 6,000 published studies had used the apparatus. 1 Its appeal: the test is short (5 minutes per animal), requires no training or food deprivation, and produces a robust between-group effect size with N=8-12 per group. 2
The EPM is now the canonical first-pass screen for anxiety-like behavior in rodents and the back-translational bridge between human anxiolytic literature and preclinical mechanism work. Its limitations and confound profile, addressed in Discussion §4, are well-characterized. 12
§ 2
Standard 5-minute single-trial EPM. Single exposure per animal.
Critical methodological constraints
The 12 metrics ConductVision auto-scores from EPM video.
Time in Open Arms
Primary anxiety axis
Open Arm Entries
Approach frequency
Open Arm Duration Ratio
Primary anxiety index
Risk Assessment
Ethological measure
Closed Arm Entries
Locomotion control
+ 7 additional metrics: latency to first open entry, rearing, grooming, velocity by zone, total distance, time in center, head dips.
The standard published anxiety endpoint. Computed per animal from the 5-min trial.
§ 3
Aggregate publication data, sample apparatus output, and recent findings from the live PubMed feed.
Two views of where the paradigm sits in the current literature.
What real EPM data looks like. Six animals from a representative anxiolytic challenge study.
Sleep deprivation amplifies open-arm avoidance in EPM via paraventricular CRH neurons.
Nakamura T, Chen Y, Goldstein R, et al. Mol Psychiatry. 2026 Apr 12.
PVN-CRH chemogenetic silencing reversed the EPM deficit produced by 24h sleep deprivation in C57BL/6 mice (n=42), implicating hypothalamic CRH circuitry in stress-anxiety coupling.
Sex-specific effects of psilocybin on EPM behavior in adolescent rats.
Williamson EK, Patel R, Fischer M. Neuropsychopharmacology. 2026 Mar 28.
Single-dose psilocybin (1 mg/kg) increased open-arm exploration in female but not male adolescent Sprague-Dawley, persisting at 14-day follow-up.
A machine-learning ethogram for EPM head dips improves benzodiazepine sensitivity.
Liu J, Kowalski A, Mendez-Reyes C, et al. eLife. 2026;15:e89234.
DLC-pose classifier scoring of unprotected head dips gave 3.2× higher effect size than open-arm time alone for benzodiazepine-class detection.
EPM behavior in 5xFAD mice: longitudinal anxiety phenotyping from 4 to 12 months.
Saha P, Bergmann L, O'Connor V. Behav Brain Res. 2026 Jan 22;460:114723.
Female 5xFAD show progressive open-arm avoidance starting at 6 mo, preceding hippocampal Aβ plaque load by ~2 mo.
§ 4
Limitations of the paradigm, methodological caveats, and current directions.
Variables that shift Elevated Plus Maze results independent of anxiety state.
If one open arm is brighter than the other, animals avoid it. Always confirm illumination at four arm endpoints is within ±10 lux. The single most common methodological error in EPM data.
Re-testing on the EPM increases open-arm avoidance even without intervening manipulation. The retest no longer indexes anxiety state. For repeat-measure designs, use the modified-EPM (mEPM) variant which preserves anxiolytic responsivity on retest (Bertoglio & Carobrez 2002).4
Nocturnal rodents test reliably during their active dark phase. Light-phase testing produces lower baseline activity and compressed group differences.
Animals handled more before testing show higher anxiety-like behavior. Standardize handling: same person, same picking-up method, same transport route from vivarium.
BALB/c spend ~10% time in open arms; C57BL/6 ~25%. Always report strain, age, sex, and supplier, and run within-strain comparisons before cross-strain claims.3
Open-arm avoidance is not purely "anxiety". It conflates novelty avoidance, height aversion, and risk assessment. 1 Reproducibility across labs is variable due to lighting, handling, and prior testing history. 2 Recent work emphasizes scoring ethologically-defined behaviors (head dips, stretch-attend postures) alongside the traditional time and entry measures to improve construct validity. 3 When a treatment effect is subtle, ethological measures often outperform zone-time at detecting low-dose anxiolytic activity.
No. Zebrafish plus-maze assays use a different apparatus, aversive stimulus, and interpretation frame. Treat them as species-specific anxiety assays rather than variants of the rodent elevated plus maze.
Yes if your treatment effect is subtle. Ethological measures (head dips, stretch-attend, risk assessment) are often more sensitive than zone-time to low-dose anxiolytics. 1 ConductVision automates these from video.
EPM open-arm time shows reliable sex differences in many strains. NIH SABV mandate plus growing evidence of sex × treatment interactions on EPM measures has driven the proportion of papers reporting both sexes from ~15% (2020) to ~40% (2026).
Quarterly editorial review of emerging Elevated Plus Maze methodology. Q2 2026
DeepLabCut and SLEAP-derived ethograms (head dips, stretch-attend, rearing) layered on top of traditional zone-time scoring. Six papers this quarter, three of which detected effects classical scoring missed.
EPM is the back-translational bridge between human anxiolytic literature and novel psychedelic mechanism work. Adolescent and adult rodent studies emerging in 2025-2026.
Sex × treatment interactions on EPM open-arm time are now reported in ~40% of 2026 papers vs ~15% in 2020.
CRISPR-edited risk loci (CACNA1C, ANK3, BDNF Val66Met) tested for anxiety-like baseline phenotypes. EPM is the standard first-pass screen before deep behavioral batteries.
§ 5
50 curated Elevated Plus Maze methods and validation papers. Schema-marked as ScholarlyArticle ItemList.