Anxiety & Depression Tests

Elevated Plus Maze

$1,890.00 - $2,290.00

Standardized behavioral assay apparatus for quantifying anxiety-like behavior in mice and rats through measurement of exploratory activity in open versus enclosed elevated arms.

Doors: Yes
Color: White
$2,290.00
Key Specifications
arm_configurationFour arms at 90 degrees
arm_typesTwo enclosed arms, two open arms
Automation Levelmanual
SpeciesMouse, Rat
SKU:ME-3301/ 3302
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Choose your configuration

Validated Elevated Plus Maze configurations

Pick the apparatus configuration that matches the cohort, species, and protocol. Species-specific adaptations should be interpreted within their own validation literature.

This productMost common

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

BuyableMouse standard

Mouse EPM

30 × 5 cm arms · 15 cm walls · 40 cm elevation

Scaled-down dimensions for mouse studies. Lister 1987 mouse adaptation.

$2,295

SpecialtyRetest paradigm

Modified-EPM (mEPM)

1 cm low ledge on open arms · same other dimensions

Preserves anxiolytic responsivity on retest. Bertoglio & Carobrez 2002.

$2,695

View mEPM →

§ 1

Introduction

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

Methods

2.1 Procedure

Standard 5-minute single-trial EPM. Single exposure per animal.

Pre-test setup

  1. 1.HabituationMove home cages to the testing room 30 to 60 minutes before the first trial. Lights set to 300 lux measured at the center of the maze.
  2. 2.Apparatus checkConfirm all four arms are level using a bubble level. Verify illumination is symmetric across arms (within ±10 lux).
  3. 3.Baseline cleaningWipe maze with 70% ethanol; allow 5 min for evaporation before the first subject.
  4. 4.CameraMount overhead camera at least 1.5 m above the maze for full top-down view. Confirm tracking software calibration.

Trial sequence

  1. 1.Place subjectCenter platform, facing closed arm. Same start position for all subjects to avoid bias.
  2. 2.Record 5:00Start tracker on subject release. Standard duration: 300 seconds.1
  3. 3.Remove subjectReturn to home cage. Note any urination or defecation.
  4. 4.Clean mazeFull 70% ethanol wipe with 90 s evaporation between subjects.
  5. 5.CounterbalanceRandomize subject order across treatment groups. Test all groups within the same daily window.

Critical methodological constraints

  • Single-trial only. Animals cannot be re-tested without losing the anxiety signal (one-trial tolerance, File & Zangrossi 1993). For repeat-measure designs use the modified-EPM (mEPM) variant.4
  • Time-of-day matters. Test all subjects within the same circadian window, preferably early dark phase for nocturnal rodents.
  • Handling consistency. Stress from handling alone shifts baseline open-arm time. Standardize handler, picking-up method, and transport route from vivarium.
  • Sample size. N=8-12 per group is standard for benzodiazepine-class effects (α=0.05, power=0.80, ~40% group difference). Subtler manipulations need N=15-20.

2.2 Measurement & Analysis

The 12 metrics ConductVision auto-scores from EPM video.

Time in Open Arms

Primary anxiety axis

Cumulative duration in unprotected open arms. Higher values indicate reduced anxiety. Sensitive to benzodiazepine challenge: a 1-2 mg/kg dose roughly doubles open-arm time in C57BL/6.1

Open Arm Entries

Approach frequency

Count of full entries (all four paws) into open arms. Read alongside total entries to dissociate anxiety from locomotor effects.

Open Arm Duration Ratio

Primary anxiety index

Open-arm time ÷ total time in either arm type. Normalizes for total exploration. The standard endpoint reported in publications.

Risk Assessment

Ethological measure

Stretch-attend postures plus protected head dips from closed-arm thresholds. Sensitive to low-dose anxiolytics that have not yet shifted open-arm time.3

Closed Arm Entries

Locomotion control

Independent control for general locomotor activity. Use to determine whether reduced total entries reflects sedation versus genuine anxiety change.

+ 7 additional metrics: latency to first open entry, rearing, grooming, velocity by zone, total distance, time in center, head dips.

2.3 Open-arm duration ratio (analysis)

The standard published anxiety endpoint. Computed per animal from the 5-min trial.

Inline calculator

Type the times your tracker recorded.

Full calculator with 95% CI →
Open arm ratio

26.5%

Formula: open arm time ÷ (open arm time + closed arm time) × 100. Reference: Pellow 1985 1 standard endpoint. C57BL/6 baseline ≈ 25%, BALB/c baseline ≈ 10%.2

§ 3

Results

Aggregate publication data, sample apparatus output, and recent findings from the live PubMed feed.

3.1 Publication trends

Two views of where the paradigm sits in the current literature.

Figure 1 · EPM publications by year (PubMed)

The paradigm has been dominant for 40 years and is still growing.

Live · Weekly

2000201020202026 YTD: 117 papers

Total in PubMed since 1985: 8,577+ papers. Updated 2026-04-29.

Figure 2 · Methods co-occurring with EPM (last 12 months)

Other paradigms most often run alongside EPM in the same paper.

Live

3.2 Sample apparatus output

What real EPM data looks like. Six animals from a representative anxiolytic challenge study.

Table 1 · Per-animal EPM scoring output

Download sample CSV →
AnimalGroupOpen time (s)Closed time (s)Open entriesOpen ratio (%)
M-001Vehicle42218316.2%
M-002Vehicle38235213.9%
M-003Vehicle54202421.1%
M-004Anxiolytic98142840.8%
M-005Anxiolytic112128946.7%
M-006Anxiolytic86158735.2%

Vehicle group mean: 17.1% open ratio. Anxiolytic group mean: 40.9%. Effect size (Cohen's d) = 4.2. Synthetic example for illustration only.

3.3 Recent findings (live PubMed feed)

  • Apr 2026PMID: 38912004

    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.

  • Mar 2026PMID: 38876221

    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.

  • Feb 2026PMID: 38756432

    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.

  • Jan 2026PMID: 38645119

    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.

View all 8577 matching papers on PubMed →

§ 4

Discussion

Limitations of the paradigm, methodological caveats, and current directions.

4.1 Common confounds

Variables that shift Elevated Plus Maze results independent of anxiety state.

Asymmetric lighting

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.

Prior testing (one-trial tolerance)

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

Time-of-day

Nocturnal rodents test reliably during their active dark phase. Light-phase testing produces lower baseline activity and compressed group differences.

Handling stress

Animals handled more before testing show higher anxiety-like behavior. Standardize handling: same person, same picking-up method, same transport route from vivarium.

Strain baseline

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

4.2 Construct validity caveats

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.

4.3 Special considerations

Is a zebrafish plus maze the same assay as rodent EPM?

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.

Should I score head dips and stretch-attend postures?

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.

Why has the field shifted toward sex-as-biological-variable reporting?

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).

4.4 Current directions

Quarterly editorial review of emerging Elevated Plus Maze methodology. Q2 2026

Rising

Pose-estimation + classical scoring fusion

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.

Rising

Psychedelic anxiolytic screening

EPM is the back-translational bridge between human anxiolytic literature and novel psychedelic mechanism work. Adolescent and adult rodent studies emerging in 2025-2026.

Methodological

Sex as a biological variable

Sex × treatment interactions on EPM open-arm time are now reported in ~40% of 2026 papers vs ~15% in 2020.

Methodological

EPM in genetic risk models

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

References

50 curated Elevated Plus Maze methods and validation papers. Schema-marked as ScholarlyArticle ItemList.

  1. Pellow S, Chopin P, File SE, Briley M. Validation of open-closed arm entries in an elevated plus-maze as a measure of anxiety in the rat. J Neurosci Methods. 1985;14(3):149-167.
  2. Walf AA, Frye CA. The use of the elevated plus maze as an assay of anxiety-related behavior in rodents. Nat Protoc. 2007;2(2):322-328.
  3. Carobrez AP, Bertoglio LJ. Ethological and temporal analyses of anxiety-like behavior: the elevated plus-maze model 20 years on. Neurosci Biobehav Rev. 2005;29(8):1193-1205.
  4. File SE, Zangrossi H Jr. "One-trial tolerance" to the anxiolytic actions of benzodiazepines in the elevated plus-maze, or the development of a phobic state? Psychopharmacology (Berl). 1993;110(1-2):240-244.
  5. Hogg S. A review of the validity and variability of the elevated plus-maze as an animal model of anxiety. Pharmacol Biochem Behav. 1996;54(1):21-30.
  6. Rodgers RJ, Dalvi A. Anxiety, defence and the elevated plus-maze. Neurosci Biobehav Rev. 1997;21(6):801-810.
  7. Lister RG. The use of a plus-maze to measure anxiety in the mouse. Psychopharmacology (Berl). 1987;92(2):180-185.
  8. Cruz APM, Frei F, Graeff FG. Ethopharmacological analysis of rat behavior on the elevated plus-maze. Pharmacol Biochem Behav. 1994;49(1):171-176.
  9. Montgomery KC. The relation between fear induced by novel stimulation and exploratory behavior. J Comp Physiol Psychol. 1955;48(4):254-260.
  10. Bertoglio LJ, Carobrez AP. Previous maze experience required to increase open arms avoidance in rats submitted to the elevated plus-maze model of anxiety. Behav Brain Res. 2000;108(2):197-203.
  11. Handley SL, Mithani S. Effects of alpha-adrenoceptor agonists and antagonists in a maze-exploration model of "fear"-motivated behaviour. Naunyn Schmiedebergs Arch Pharmacol. 1984;327(1):1-5.
  12. Dawson GR, Tricklebank MD. Use of the elevated plus maze in the search for novel anxiolytic agents. Trends Pharmacol Sci. 1995;16(2):33-36.
  13. Cole JC, Rodgers RJ. An ethological analysis of the effects of chlordiazepoxide and bretazenil on the behaviour of mice in the elevated plus-maze. Behav Pharmacol. 1993;4(6):573-580.
  14. Treit D, Menard J, Royan C. Anxiogenic stimuli in the elevated plus-maze. Pharmacol Biochem Behav. 1993;44(2):463-469.
  15. Pellow S, File SE. Anxiolytic and anxiogenic drug effects on exploratory activity in an elevated plus-maze: a novel test of anxiety in the rat. Pharmacol Biochem Behav. 1986;24(3):525-529.
  16. Wall PM, Messier C. Methodological and conceptual issues in the use of the elevated plus-maze as a psychological measurement instrument of animal anxiety-like behavior. Neurosci Biobehav Rev. 2001;25(3):275-286.
  17. Cruz-Morales SE, Santos NR, Brandão ML. One-trial tolerance to midazolam is due to enhancement of fear and reduction of anxiolytic-sensitive behaviors in the elevated plus-maze retest in the rat. Pharmacol Biochem Behav. 2002;72(4):973-978.
  18. Holmes A, Rodgers RJ. Responses of Swiss-Webster mice to repeated plus-maze experience: further evidence for a qualitative shift in emotional state? Pharmacol Biochem Behav. 1998;60(2):473-488.
  19. Dalvi A, Rodgers RJ. GABAergic influences on plus-maze behaviour in mice. Psychopharmacology (Berl). 1996;128(4):380-397.
  20. Espejo EF. Structure of the mouse behaviour on the elevated plus-maze test of anxiety. Behav Brain Res. 1997;86(1):105-112.
  21. Crawley JN. Exploratory behavior models of anxiety in mice. Neurosci Biobehav Rev. 1985;9(1):37-44.
  22. Rodgers RJ, Cao BJ, Dalvi A, Holmes A. Animal models of anxiety: an ethological perspective. Braz J Med Biol Res. 1997;30(3):289-304.
  23. Hagenbuch N, Feldon J, Yee BK. Use of the elevated plus-maze test with opaque or transparent walls in the detection of mouse strain differences and the anxiolytic effects of diazepam. Behav Pharmacol. 2006;17(1):31-41.
  24. Shepherd JK, Grewal SS, Fletcher A, et al. Behavioural and pharmacological characterisation of the elevated "zero-maze" as an animal model of anxiety. Psychopharmacology (Berl). 1994;116(1):56-64.
  25. Trullas R, Skolnick P. Differences in fear motivated behaviors among inbred mouse strains. Psychopharmacology (Berl). 1993;111(3):323-331.
  26. Griebel G, Belzung C, Misslin R, Vogel E. The free-exploratory paradigm: an effective method for measuring neophobic behaviour in mice and testing potential neophobia-reducing drugs. Behav Pharmacol. 1993;4(6):637-644.
  27. Belzung C, Griebel G. Measuring normal and pathological anxiety-like behaviour in mice: a review. Behav Brain Res. 2001;125(1-2):141-149.
  28. Korte SM, De Boer SF. A robust animal model of state anxiety: fear-potentiated behaviour in the elevated plus-maze. Eur J Pharmacol. 2003;463(1-3):163-175.
  29. Ramos A, Berton O, Mormède P, Chaouloff F. A multiple-test study of anxiety-related behaviours in six inbred rat strains. Behav Brain Res. 1997;85(1):57-69.
  30. Bourin M, Hascoët M. The mouse light/dark box test. Eur J Pharmacol. 2003;463(1-3):55-65.
  31. Walf AA, Frye CA. Estradiol decreases anxiety behavior and enhances inhibitory avoidance and gestational stress produces opposite effects. Stress. 2007;10(3):251-260.
  32. Frye CA, Walf AA. Estrogen and/or progesterone administered systemically or to the amygdala can have anxiety-, fear-, and pain-reducing effects. Behav Neurosci. 2004;118(2):306-313.
  33. Borta A, Wöhr M, Schwarting RKW. Rat ultrasonic vocalization in aversively motivated situations and the role of individual differences in anxiety-related behavior. Behav Brain Res. 2006;166(2):271-280.
  34. Ennaceur A, Michalikova S, Chazot PL. Models of anxiety: responses of rats to novelty in an open space and an enclosed space. Behav Brain Res. 2006;171(1):26-49.
  35. Bouwknecht JA, Paylor R. Behavioral and physiological mouse assays for anxiety: a survey in nine mouse strains. Behav Brain Res. 2002;136(2):489-501.
  36. Carola V, D'Olimpio F, Brunamonti E, Mangia F, Renzi P. Evaluation of the elevated plus-maze and open-field tests for the assessment of anxiety-related behaviour in inbred mice. Behav Brain Res. 2002;134(1-2):49-57.
  37. File SE. The use of social interaction as a method for detecting anxiolytic activity of chlordiazepoxide-like drugs. J Neurosci Methods. 1980;2(3):219-238.
  38. Lecci A, Borsini F, Volterra G, Meli A. Pharmacological validation of a novel animal model of anticipatory anxiety in mice. Psychopharmacology (Berl). 1990;101(2):255-261.
  39. Holmes A, Parmigiani S, Ferrari PF, Palanza P, Rodgers RJ. Behavioral profile of wild mice in the elevated plus-maze test for anxiety. Physiol Behav. 2000;71(5):509-516.
  40. Adamec R, Walling S, Burton P. Long-lasting, selective, anxiogenic effects of feline predator stress in mice. Physiol Behav. 2004;83(3):401-410.
  41. Bourin M, Petit-Demoulière B, Dhonnchadha BN, Hascöet M. Animal models of anxiety in mice. Fundam Clin Pharmacol. 2007;21(6):567-574.
  42. McNaughton N, Corr PJ. A two-dimensional neuropsychology of defense: fear/anxiety and defensive distance. Neurosci Biobehav Rev. 2004;28(3):285-305.
  43. Calatayud F, Coubard S, Belzung C. Emotional reactivity in mice may not be inherited but influenced by parents. Physiol Behav. 2004;80(4):465-474.
  44. Albrechet-Souza L, Borelli KG, Brandão ML. Activity of the medial prefrontal cortex and amygdala underlies one-trial tolerance of rats in the elevated plus-maze. J Neurosci Methods. 2008;169(1):109-118.
  45. Falter U, Gower AJ, Gobert J. Resistance of baseline activity in the elevated plus-maze to exogenous influences. Behav Pharmacol. 1992;3(2):123-128.
  46. Mechiel Korte S, De Boer SF. A robust animal model of state anxiety: fear-potentiated behaviour in the elevated plus-maze. Eur J Pharmacol. 2003;463(1-3):163-175.
  47. Doremus-Fitzwater TL, Varlinskaya EI, Spear LP. Social and non-social anxiety in adolescent and adult rats after repeated restraint. Physiol Behav. 2009;97(3-4):484-494.
  48. Padovan CM, Guimarães FS. Restraint-induced hypoactivity in an elevated plus-maze. Braz J Med Biol Res. 2000;33(1):79-83.
  49. Rosa VP, Vandresen N, Calixto AV, Kovaleski DF, Faria MS. Temporal analysis of the rat's behavior in the plus-maze: effect of midazolam. Pharmacol Biochem Behav. 2000;67(1):177-182.
  50. Carobrez AP, Teixeira KV, Graeff FG. Modulation of defensive behavior by periaqueductal gray NMDA/glycine-B receptor. Neurosci Biobehav Rev. 2001;25(7-8):697-709.
Elevated Plus Maze
Elevated Plus Maze
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