Open Field test is a popular protocol used to assess exploratory behavior and anxiety. Thigmotaxis in the open field is used to evaluate anxiolytic, anxiogenic and even non-pharmacological treatments. Ambulation is the most common behavior studied with this maze, but others such as latency or rearing can also be measured. In addition, objects can be added for a modification similar to the novel object recognition field.
- Walls can be both opaque or clear. We recommend that clear walls are used for measurements of anxiety, while opaque walls are used if assessments include novel object recognition.
- Walls are easily detachable for easy cleaning.
- Grid floor insert available for video tracking.
$ 590+ Shipping and Handling (approx $100)
- Removable base for easy clean
- Easy clean with 70% Ethanol
- Matte Finish for non shine
- No odors
$ 790+ Shipping and Handling (approx $150)
- Removable base for easy clean
- Easy clean with 70% Ethanol
- Matte Finish for non shine
- No odors
$ 440+ Shipping and Handling (approx $80)
- Removable base for easy clean
- Large singular box can serve as large Open Field
- Separator included to divide into 4 individual mouse/rat boxes
- Easy clean with 70% Ethanol
- Matte Finish for non shine
- No odors
Mouse (Set of 4)
$ 1790+ Shipping and Handling (approx $300)
- With wall insert
Rat (Set of 4)
$ 1890+ Shipping and Handling (approx $400)
- With wall insert
XS (Stroke - Set of 4)
$ 1590+ Shipping and Handling (approx $150)
- With wall insert
Mouse - 40x40cm to fit
Rat - 60x60cm to fit
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Open Field Test (OFT) is a simple apparatus used in the assessment of locomotion, exploration, and anxiety. The open field task explores the innate responses of the subject to open spaces apart from their explorative drive. Thigmotaxis is often seen in animals such as rats and mice. This behavior of avoiding brightly lit open spaces is believed to be an evolutionary adaptive behavior that can be observed in many species. The Open-Field test exploits this fear in species to evaluate the different aspects of anxiety-related behaviors. Animals with a decreased level of anxiety are more likely to explore the central area of the open arena than animals with high levels of anxiety. Animals with high levels of anxiety will display reduced locomotion and exploration, with a preference to stay close to the walls of the open field arena. However, despite the fear, animals have also been known to explore threatening stimulus as part of their exploratory drive.
The apparatus was developed in the early 1930’s by Calvin S. Hall to observe rat behavior in an open arena (Hall & Ballechey 1932). Hall and Ballachey’s experiment used a square arena that was marked into a grid. The experiment involved the observation of the rats to food stimulus placed within a barrier in the center of the arena. This experiment allowed observation of the influence of a positive stimulus on thigmotaxic behaviors of the rats and their emotionality. Though the apparatus is useful in the assessment of anxiety and explorative behaviors, it is debated that the task does not provide a specific measure of anxiety. To overcome these shortcomings, the 3-D Open Field apparatus can be used to allow a more precise measure of anxiety and fear-related behaviors.
The Open Field Test is usually used alongside other mazes that measure anxiety, such as the Elevated Plus Maze, Elevated Zero Maze, and Elevated Y-Maze (see also T-Maze), following anxiolytic and anxiogenic drug treatments. The Ziggurat task is a variation of the Open Field apparatus that uses ziggurats in the open space to create a complex environment. Another task that uses a similar apparatus to the Open-Field task is the Novel Object Recognition task used to evaluate the subject’s responses to novel objects.
The Open Field apparatus has a simple construct. Usually, a square arena that is surrounded by high walls to prevent escaping is used, though circular arenas are also used. These walls can be transparent to allow the subject to view any visual stimuli placed around or can be opaque to limit observation to behaviors in response to brightly lit open spaces. The floors are often marked with square grid crossings, and the center of the arena is marked with a square. In addition, the apparatus can have additions and modifications to test different behaviors and responses.
The first use of an Open-Field was described in Hall and Ballechey’s 1932 paper, “A study of the rat’s behavior in a field: a contribution to method in comparative psychology.” In their experiment, they utilized a 7 x 7-foot walled arena that had been marked into 49 square grids. In the center, a cylinder wire mesh covering 25 squares was placed to contain a food reward. When the animals were introduced into the arena from a start point, it was observed that the presence of food reward resulted in animals circling the wire-mesh barrier more than when no food reward was present. A similar set-up was once again used by Hall in his 1934 experiment to highlight “the importance of needs or drives and emotionality as factors determining adjustment or maladjustment” (Hall, 1934a). In the same year, Hall published a paper aimed at validating the correlation between the defecation and urination and the individual emotionality of the rats in an open-field task (Hall, 1934b). Although, it has been argued that a measure of defecation or urination simply measures timidity in a controlled environment.
Hall’s experiment for determining the relationship between emotional behavior and the speed of ambulatory activity in an open-field task suggested that emotional rats tended to be less active than their non-emotional counterparts (Hall, 1936). This behavior was further observed by Hall in the “The inheritance of emotionality” paper published in 1938. In the experiment, it was observed that males were more likely to be emotional than the females and the quality of emotionality was inheritable as evident from the higher defecation and urination rates of the progeny of most emotional males and females compared with the progeny of least emotional males and females (Hall, 1938).
Since its initial use as a test for emotionality by Hall, the Open-Field task has seen different modifications and adaptations and a wider range of applications. In 1945, Anderson utilized the open-field task to assess timidity and role of gender in timidity in normal and gonadectomized rats. The results of the investigation showed that the females were less timid than their male counterparts and that gonadectomy before puberty did not affect the sex difference in timidity,
Stern (1957) evaluated the effect of frontal area lesions on the behavioral performances of male albino rats in an open-field task. The author found that the subjects with frontal lesions showed similar and long-lasting behavioral changes in the open field as animals subjected to a series of electroconvulsive seizures (ECS). Subjects showed an increase in emotionality and changes in behavior was more gradual than in the ECS animals.
The effect of aging on the open-field behavior was evaluated by Werboff and Havelena in their 1962 paper. Their test assessed the performances of both sexes of Sprague-Dawley at ages 90, 180, 360, and 540 days. The evaluation of age and gender-based performance in the open-field concluded that activity and emotionality declined with increasing age and that the females exhibited higher activity and emotionality scores than the males.
Levine et al. evaluated the relationship between open-field behavior and changes in adrenal corticoid in male Purdue-Wistar rats. The animals were grouped into two groups based on if they had been handled in infancy or not. The animals were tested on the open-field for 4 days in their adulthood and were immediately killed at the termination of the test. As expected animals that were handled in their infancy were more active in the open-field task, defecated less on all days of testing and had lesser corticosterone response throughout the testing period.
Itoh et al. investigated the behavioral effects of neuromedin B (NMB) and neuromedin C (NMC) in an open-field task using male Wistar rats. Subjects were intracerebroventricularly (ICV) administered either 5 μl peptide or saline and tested at 1 and 30 minutes after administration in the open-field. At both evaluation points a decrease in the duration of locomotion, the distance moved, and rearing behavior was observed with an increase in excessive grooming and violent scratching. However, the pronounced behavioral changes after 30 minutes was only observed in NMC administered rats.
Brotto’s et al. experiment assessed the effect of chronic melatonin administration and sex differences in forced-swim test and open-field task. Results from both the test showed that females displayed higher activity than the males. Melatonin administration led to decreased activity in the forced-swim test while increasing ambulatory behavior in the open-field task for both genders. The study concluded based on both the tests results that melatonin, in general, did not have an inhibitory effect on the motor activities of the subjects.
Popović et al. tested the effects of low and high doses of scopolamine on the open field habituation task using male Wistar rats. Subjects were administered either 1 mg/kg (low dose) or 30 mg/kg (high dose) of scopolamine soon after their acquisition task in the open-field. Behavioral observation of the subjects after reintroduction to the open-field after 48 hours showed that subjects treated with a low dose significantly decreased grooming while the opposite was true for subjects treated with high dose of scopolamine. Further, the defecation rate was maintained in the low dose group while it increased significantly in the high dose group. Based on the data it was concluded that post-training scopolamine administration increased defecation and grooming, behaviors that are associated with fear and stress.
Apparatus and Equipment
The Open Field apparatus is a square arena that is available in a 27 x 27 cm and 50 x 50 cm sizes to accommodate different sized animals. The arena is surrounded by high walls to prevent the subjects from escaping the apparatus. In general, the walls are clear. However, opaque colors and matte finish are also available. Floor inserts for the apparatus are available with or without gridlines. These gridlines divide the area into equal smaller squares and can be helpful for both manual scoring, as well as video recording and scoring with tracking software. A square area in the very center of the area may also be outlined.
Literature Review: Disease Model
|Title||Authors, Year published, Journal||Subject||Disease Model||Comments / Outcome|
|Stress inhibits psychomotor performance differently in simple and complex open field environments.||Faraji J, Soltanpour N, Jafari SY, Moeeini R, Pakdel S, Moharreri A, Metz GA.|
Hormones and behavior.
|Adult male Long-Evans rats||Stress||Subjects underwent seven days of restraint stress or no-stress conditions and were individually tested in the open field, central ziggurat and 16 ziggurat tasks.|
No stress-induced changes were revealed by the simple open-field arena.
|Quantitative evaluation of 3D mouse behaviors and motor function in the open-field after spinal cord injury using markerless motion tracking.||Sheets AL, Lai PL, Fisher LC, Basso DM.|
|C57BL/6J mice||Spinal cord injury||Based on the Basso Mouse Scale (Basso et al., 2006) subjects were divided into mild, moderate and severe spinal cord injury groups.|
|Reduction in open field activity in the absence of memory deficits in the AppNL-G-F knock-in mouse model of Alzheimer’s disease.|
|Whyte LS, Hemsley KM, Lau AA, Hassiotis S, Saito T, Saido TC, Hopwood JJ, Sargeant TJ.|
Behavioral Brain Research
|AppNL-G-F knock-in (C57BL/6J background)||Alzheimer’s disease|
|AppNL-G-F knock-in showed a reduction in locomotor/exploratory activity in an open field, despite a lack of demonstrated cognitive deficits in other behavioral tests.|
|Assessment of anxiety in the open field and elevated plus maze using infrared thermography.|
|Lecorps B, Rödel HG, Féron C.|
Physiology and Behavior
|Domestic mice||Anxiety||Subjects that spent more time in the central zone of the open field during the duration of the test showed a stronger decrease in standard deviation of temperatures.|
Initial tail and eye temperature measured immediately after entering the animals into the OF arena were significantly and positively correlated with the distance the animals covered during the first 5 minutes of testing.
Literature Review: Pharmacological Studies
|Drug / Toxin||Title||Authors, Year published, Journal||Subject||Comments / Outcome|
|Propranolol||Propranolol reverses open field effects on frustration.||Justel N, Psyrdellis M, Pautassi RM, Mustaca A|
Neurobiology of learning and memory
|Male Wistar rats||Incentive relativity was studied using the consummatory successive negative contrast (cSNC) paradigm.|
Subjects exposed to the open-field showed the higher consummatory behavior of the downshifted reward than animals without OF exposure. Propranolol blocked the effect of OF before OF exposure but not after OF exposure.
Subjects that explored OF showed an enhanced contrast in comparison to controls in OF exposure prior to second post-shift trial. These effects were blocked by propranolol administration applied before or after OF exposure.
|Lithium||Lithium ameliorates open-field and elevated plus maze behaviors, and brain phospho-glycogen synthase kinase 3-beta expression in fragile X syndrome model mice.||Chen X, Sun W, Pan Y, Yang Q, Cao K, Zhang J, Zhang Y, Chen M, Chen F, Huang Y, Dai L, Chen S|
|Fmr1 knockout mice||Lithium significantly decreased total distance, crossing, central area time, and center entry in the open-field test (p<0.05).|
|Phenazepam||Effects of phenazepam on the behavior of C57BL/6 and BALB/c mice in the open field test after naloxone pretreatment.||Seredenin SB, Nadorova AV, Kolik LG, Yarkova MA.|
Bulletin of experimental biology and medicine
|C57BL/6 and BALB/c mice||Naloxone increased motor activity BALB/c mice and decreased motor activity in C57Bl/6 mice in the open field in.|
Naloxone potentiated the activating effects of phenazepam on the open-field behavior of BALB/c mice and slightly increased the sedative effect of this drug in C57Bl/6 mice, in the combined treatment trials.
|Amphetamine||Differential sensitivity to amphetamine’s effect on open field behavior of psychosocially stressed male rats.||Pohorecky LA, Sweeny A, Buckendahl P.|
|Male adult Long-Evans rats||Subjects were either diad-housed or single housed and designated as dominant (DOM) or subdominant (Sdom) based on the agnostic behaviors. Subjects were tested in an open field after injections of saline or amphetamine (0.9 or 2.7 mg/kg IP) prior to and again while diad-housing.|
At the pre-diad test, amphetamine treatment elevated locomotor activity of all rats, while stimulation of center entries was more marked in future DOM rats. At the diad test, amphetamine’s locomotor stimulant effect was evident in all experimental groups with DOM rats showing higher effects compared to Sdom and single-housed rats.
|Caffeine||Strain-dependent effects of acute caffeine on anxiety-related behavior in PVG/c, Long-Evans, and Wistar rats.||Hughes RN, Hancock NJ.|
Pharmacology, biochemistry, and behavior
|PVG/c, Long-Evans, and Wistar rats||For all three strains, increased occupancy of the center of the open field suggested caffeine-induced anxiolysis while increased grooming in the open field suggested caffeine-induced angiogenesis.|
Caffeine also increased open-field ambulation for PVG/c rats and walking for all rats.
Several overall sex differences were also observed that supported female rats being more active and less anxious than males.
Open-Field test is used in the assessment of exploration, locomotion, and anxiety. The test can be used to compare animals in a sham control group to animals in a treatment or disease model group by observing their behaviors and tracking their movements in the Open Field. Animals with minimal anxiety are likely to move about the area and perform other behaviors such as grooming and rearing, while animals with increased anxiety may freeze or exhibit stretch attend postures.
Prior to beginning the experiment, the apparatus should be thoroughly cleaned to prevent the influence of any lingering stimuli. Overhead lighting set-up is recommended to prevent shadows. The arena should be sufficiently, but dimly, lit to allow subject to see and explore their surroundings while avoiding stress from bright lights. Observation of the Open-Field task can be done using tracking software and video camera, such as Noldus Ethovision XT, mounted above the apparatus. Live scoring is also possible.
Since the Open Field task is based on the novelty of the environment, the test does not require any pre-training. The subject is placed in the center of the arena, and its behaviors are observed for a period of at least 5 minutes without any interference.
The simplicity of the Open Field apparatus makes it a highly modifiable apparatus. Simple modifications include using opaque walls, different lights, different floor inserts (shock floor inserts) and varying the size of the arena. Each modification can be tailored to the needs of the research with the Open Field apparatus.
The Ziggurat task apparatus is a modification of the Open Field that uses ziggurats to create a complex environment for the subject to explore. The task involves assessment of the subject’s spatial memory and navigation (Faraji et al., 2008). The Novel Object Recognition task is another battery that uses apparatus similar to the Open Field task. This task is commonly used in the assessment of memory and response to novel objects (Bevins & Besheer 2006, Leger et al., 2013).
The Social Defeat application of the apparatus is used to the underlying mechanisms of affective-like disorders (Jöhren et al., 1994). This apparatus has also been applied for the development and understanding of new drugs and treatments (Berton and Nestler 2006, Berton et al., 2006).
Modification of the protocol can also be of interest in research. Repeated exposure to the Open-Field apparatus can be used to evaluate habituation behaviors of the animals.
The primary observation made using the Open Field apparatus is the behavioral response of the subjects to the open space. Subjects with less anxiousness in the open arena usually will explore the entire space. However, subjects treated with anxiogenics or disease models such as stress, will avoid the central arena and stay close to the walls. The following parameters can be measured using the Open Field task,
- Frequency of line crossing: The number of times the subject crosses the grid lines on the grid floor insert with all four of its paws.
- Frequency of central square entries: The number of times the subject enters the center of the arena marked by the square on the grid floor insert.
- Time spent in the center of the arena: The duration of time spent in the center of the arena.
- Time spent close to the walls: The duration of time spent staying close to the walls of the arena.
- Frequency of rearing behavior: The number of times the subject stands on its hind paws. In general, unsupported rearing (subject does not rest its front paws on the walls) is a better measure of anxiety.
- Frequency of stretch attend postures: The number of times the subject elongates forward its head and shoulders and retracts it.
Other observable behaviors can include urination/defecation, grooming and climbing behaviors.
The Open-Field test has also been directly applied in human studies. Walz et al. utilized a soccer field to evaluate thigmotaxic behaviors in human participants with agoraphobia or high anxiety sensitivity. Participants’ behavior data was recorded using GPS and heat maps in addition to visual analyses. It was observed that participants with agoraphobia and high anxiety sensitivity showed enhanced thigmotaxis as evident from the long durations spent close to the walls and reluctance to explore the central area. This behavior was further observed in the city walk experiment; wherein, the participants walked through a market area to allow observation of real-life behavior. Observations of both experiments, Open Field task and real-life scenario, strongly suggested that thigmotaxis is related to agoraphobia and anxiety sensitivity.
A study by Perry et al. evaluated over-activity and exaggerated goal-directed behavior in an attempt to distinguish manic bipolar disorder (BD) from highly activated states of schizophrenia (SCZ). Subjects selected for the study included patients with Bipolar Disorder, (Current Episode Manic), Schizophrenia-paranoid subtype and Schizophrenia non-paranoid subtype (including disorganized or undifferentiated) between the ages of 18 to 55 participated. Non-patients were used as controls. For their experiment, Perry et al. used an open field setting scattered with novel and interactable objects to monitor the behavioral patterns of the participants. The 15-minute experiment revealed that patients with Bipolar Disorder showed greater physical interaction with the objects in the open field, more perseverative and socially disinhibited behaviors relative to Schizophrenia patients and non-patients. Further, the investigation was also able to observe distinctive behaviors between different subtype of schizophrenia. Using a similar open field set-up, Henry et al. examined the effect of methamphetamine dependence on inhibitory deficits using 16 abstinent methamphetamine-dependent individuals and 18 matched drug-free comparison subjects. The result from the experiment revealed that abstinent methamphetamine-dependent individuals displayed increased interaction with novel objects in the open field task suggesting impaired inhibition.
The availability of latest technology also makes execution of the open-field task using virtual reality a possibility. With virtual reality, setting up of different open field environments with varying levels of complexity can be easily accomplished. Environments can include an apartment room, a closed room, cityscape or an outdoor nature set-up. The benefit of the virtual environments is that they are easily modifiable, cost-effective and provide a safe environment for the participants.
Strength and Limitations
The Open-Field task is a simple apparatus that is both easy to construct and use. Since the apparatus does not require any pre-training, the evaluations can be performed in a much shorter time in comparison to other tests of anxiety. The simplicity of the apparatus makes it easy to adapt it for different investigations such as assessment of effects of aging, drugs, and lesions on behaviors of the animals. Open-field apparatus can also be used to evaluate social defeat, hopelessness or in novel object recognition task.
Using the open-field task behaviors of treatment or disease model animal groups can be compared with sham and normal group of animals to help understand the behaviors of the former group and develop and improve treatments. Apart from testing the animals to the novelty of the open arena, animals can also be subjected to habituation task by reintroducing them to the arena. This allows improvement in the understanding of habitation behaviors of animals. Availability of virtual open-field tasks also allows direct application of the assay in human subjects, with the capability of easy modification of virtual environments
Though the Open-Field task is a straightforward and simple assay, it is debated that it does not differentiate between anxiety and fear induced behaviors. This can be remedied by using a 3D Open-Field apparatus that does not provide any safe regions, unlike the open-field arena’s walls. Further, since the open-field task does not provide a specific measure of anxiety, it is recommended that it should be used in combination with other behavioral assays. It is also important to remember that many different processes play into the behaviors observed during the task.
Apart from these limitations, the handling of the animal, gender and the intensity of the light used can also influence the outcome of the open-field test. Further, the apparatus must be cleaned before every use to prevent the influence of any lingering stimuli.
- Open field test was developed by C. S. Hall in the early 1930’s.
- Open Field task is used in the assessment of locomotion, exploratory and anxiety-related
- Open field task explores the innate thigmotaxic responses and exploratory drive.
- Hall’s used the rate of defecation and urination as a measure of emotionality.
- Open field test is a simple and easily modifiable apparatus with a wide range of research applications including aging, drug effects, and lesions.
- Open field task may not provide a specific measure of anxiety. Hence, it should be used in conjunction with other behavioral batteries.
- Open field task may also not satisfactorily differentiate anxiety from fear.
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Whyte LS, Hemsley KM, Lau AA, Hassiotis S, Saito T, Saido TC, Hopwood JJ, Sargeant TJ (2018). Reduction in open field activity in the absence of memory deficits in the AppNL-G-F knock-in mouse model of Alzheimer’s disease. Behav Brain Res. 336:177-181. doi: 10.1016/j.bbr.2017.09.006.