This study has been supported by the grant NIHM R01 MH091816 and R21 MH084043 to TDG.

1. Materials and Method
1.1. The water tanks
The cylindrical tanks (30 cm height x 20 cm diameters) required for the mouse forced swim test (FST) in our laboratory are constructed of transparent Plexiglas, as this material is able to withstand the frequent movement of the tanks and accidents better than glass. The water level is 15 cm from the bottom and should be marked on the tank to ensure that the volume of water is consistent across mice. The number of tanks should ideally be at least twice as many as the number of mice being tested at a time, so that the second water tank set can be filled while the first set is in use. The dimensions of the tanks should be selected in a way that the mice will not be able to touch the bottom of the tank, either with their feet or their tails, during the swimming test. The height of the tank should be high enough to prevent the mice from escaping from the tank. Please note that the diameter of tank and the depth of water are important parameters that can be adjusted to change the behavior of mice (for a detailed analysis of these issues see1-3). 
1.2. Thermometer
A water resistant infrared thermometer is preferable, since rapid measurement of temperature reduces the amount of time required to conduct the test. However, a glass mercury thermometer will also be sufficient for this task.
1.3. Timer
1.4. Video recording device
We use a video camera supported by a tripod. Since this test usually involves multiple animals being tested at the same time, live scoring will be very difficult and is not advisable. The video camera should record in high enough resolution to render a quality picture that will be used later for behavioral scoring. Always make sure there is sufficient recording memory in the camera before starting the test. We use a video camera that records digitally without the use of mechanical media (i.e. video cassette), allowing for digital transfer of videos. If there are excessive reflections on the tanks, which may occur in laboratory environments with overhead fluorescent illumination, you may want to use a polarizing lens filter with your camera.
1.5. Dividers
In our lab we have two sets of dividers (35 cm height x 22 cm width x 22 cm depth). These are rectangular with three walls and are used as both background and as dividers between tanks to prevent mice from seeing each other during the test and potentially altering their behaviors. One set can be black for albino and light colored animals; the other set can be light colored for dark colored animals in order to render high contrast. The experimenter should make sure that the surfaces of the dividers are not overly reflective so that they alter camera images, or render major differences between illumination levels.
1.6. White noise generator
This is needed in laboratory environments in which sudden loud noises can be heard that would potentially startle the animals. The noise generator will mask such intermittent disturbing sounds. The volume level of the white noise generator should be selected to be above other ambient and unexpected noises. In our experimental room the ambient noise level (without the white noise generator activated) is 60 dB. The total noise level with the white noise generator activated at the location where the tanks are placed is 70-72 dB. However it should be noted that these figures are provided as example only, and each laboratory should select the right noise levels according to their unique environment and circumstances.
1.7. Drying paper and heat lamp
Before returning the animals to their home cages, it is important to dry them gently using paper towels and it is helpful to use a heat lamp (be certain the exposure temperature does not exceed 32°C) to prevent hypothermia.
2. Behavioral Procedures
<ol>
 <li>The overall experimental design should reflect proper counterbalancing between variables specific to your experiment. For example, in our experiments, we try to represent each group equally in every FST session (i.e., if there are four treatment groups, each will be represented in each session). Also, mice are rotated, such that mice from each treatment group are placed in a different tank in each session. </li>
 <li>Place the camera and the dividers in position. The camera should be as close as possible in order to obtain the highest possible resolution of the mice.</li>
 <li>The tanks should be filled with tap water set at the room temperature (23-25°C) to the determined level, which is marked on the tank walls. If your facility does not have constant hot/cold water, you may want to prepare hot water and/or ice to quickly bring the water to the right temperature. Check the water temperature with the infrared thermometer. Alternatively, if the temperatures of hot and cold water are constant at your facility, you can draw on the tank two marks – one for the level of hot water and a second mark for the addition of cold water – to get close to the correct final water temperature rapidly.</li>
 <li>Start the white noise generator, if being used, before the mice are introduced to the testing room. The level of white noise should only be enough to mask external noises. Avoid a high volume and make sure the same level of white noise is being used for all animals.</li>
 <li>Bring the animals into the testing room. If the colony room where the animals reside and the testing room are adjacent or very close to each other, the ambient conditions are similar and the disturbance during the moving of the cage is minimal, then no acclimation period will be necessary. Otherwise, place the animals in the testing room for a period of acclimation (generally at least one hour). If an acclimation period is necessary, make sure the acclimated animals will not be affected by the mice being tested at the same time in the same room. Please be aware that olfactory and ultrasonic cues can be sensed by the other animals placed in the same room.</li>
 <li>Start video recording before placing the animals into the water tanks.</li>
 <li>Hold the animal by its tail, and gently and slowly place in the water. Once the mice is in the water, slowly release the tail. Typically, using this procedure will prevent the animal's head from being submerged under the water. </li>
 <li>Place the mice in the tanks in an order in which the obstruction of recording will be minimized. This order, of course, should be decided in conjunction with the counterbalancing of groups and other requirements specific to your experimental design.</li>
 <li>Once all mice are in the tanks-start the countdown on the stopwatch. The usual test length for mice is six minutes in the FST.</li>
 <li>During the test be certain you are at a reasonable distance from the animals and do not make any movements or noise that may be noticed by the animals. Mice can readily float in water, however, if either a new strain of mice or a new compound being tested without previous knowledge of their effect on swimming behavior, the experimenter should monitor the animals more closely. In contrast to rats, mice do not typically dive during the FST, however in the event of diving the mouse should be removed from the tank. If the experimenter leaves the room the mice should be monitored by video in the event that a mouse cannot maintain swimming and floating behavior and to stop the test if necessary.</li>
 <li>At the end of six minute testing period stop the recording. In our lab, we show a note in front of the camera that identifies the animals at the very end of each recording. When using this approach the individual subsequently scoring the recording will not know the identity of the animals since the identity is only shown at the very end of the recording. This prevents any identification and record keeping problems that may occur later related to the recordings. Regardless of the record keeping strategy that is being used, it should clearly identify the animals and also prevent the individual later scoring the test from having knowledge of group assignments. </li>
 <li>Remove the animals from the water by their tails in the same order that you put them in and gently dry them with a drying paper and place back into their homecage.</li>
</ol>
3. Behavior Analysis
<ol>
 <li>The mouse version of FST is typically, from start to finish, six minutes long. However, generally only the last four minutes of the test are analyzed. This is due to the fact that most mice are very active at the beginning of the FST, and the potential effects of the treatment can be obscured during the first two minutes.</li>
 <li>In our laboratory we upload the video files directly from the camera to a PC and do the analysis on the PC.</li>
 <li>During the behavioral analysis, the time that each mice spends mobile is measured. The total amount of mobility time is then subtracted from the 240 seconds of test time and is then stated as the immobility time. While it is possible to measure the immobility time directly, in our laboratory we have found it easier to detect and measure active movements rather than the lack of such movements. </li>
 <li>The most important aspect of behavioral analysis and usually the biggest source of variability between observers in the FST is the correct identification of movements that are counted as bona fide mobility. Our operational definition for mobility in the FST is any movements other than those necessary to balance the body and keep the head above the water4. Mice generally float in water readily, however they still manifest small movements to balance their bodies and keep their heads above the water. These behaviors are not an attempt to escape and should not be scored as mobility. Also, after a single bout of mobility, even though essentially immobile, mice can still drift in the water as a result of momentum. These movements also should not be scored as mobility. </li>
 <li>In our laboratory, we use an on-screen stopwatch software (Xnote Stopwatch, dnSoft Research Group) for time measurements. Two separate stopwatches are used on the screen. The first stopwatch counts down from 240 seconds and alerts the observer when the behavioral analysis period ends. The second stopwatch measures the time spent mobile. Some stopwatch software has the ability to assign keys to start and stop functions, so that on-screen stopwatches can be controlled by the keyboard. In our lab, instead of a regular keyboard, we use an input device commonly known as a 'gamepad' to control the stopwatches.</li>
 <li>When using a PC to quantify immobility, if there is more than one mouse tested and present on the screen, it is a good idea to cover the other animals (you can use another program window or physically cover the screen with paper), so that their movements will not distract the observer. </li>
 <li>If an on-screen stopwatch is used, be certain to cover all but the millisecond decimals of the stopwatch. The reason for this is to prevent bias in the observer, while still allowing the ability to determine if the watch is running or not running. Since the observer, while blind to the group assignments of the animals, will have a general idea of level of mobility in the mice, there might be some bias occurring if she is allowed to see the total amount of mobility time elapsed for that particular mouse before completion of the analysis session. By covering the stopwatch, she will only know whether the stopwatch is on or off at any point but will not know the total time elapsed and therefore cannot be effected by any bias.</li>
 <li>An inter-observer reliability test should be conducted for every new observer before beginning to collect data from test animals. In our laboratory, each new observer first watches an experienced observer scoring. After the new observer gains confidence to differentiate mobility from immobility, they then score with the experienced observer watching and pointing out any mistakes. Once this phase is successfully completed, the new observer will analyze a specific set of FST videos that we keep in our laboratory for training purposes. Only after a high level of inter-observer correlation is obtained with the experienced observer does an investigator start analyzing FST videos in actual experiments. We archive the data from these training analyses to constitute an internal standard for the laboratory for future use. We have observed differences between strains in the manner in which they express mobility (and immobility) behaviors, and mean immobility time between sexes. When a new strain, sex, or genetically modified mouse model is tested in the laboratory it is necessary to again undertake this type of reliability analysis. </li>
</ol>
4. Representative Results
There are marked differences between genetically distinct inbred and outbred mouse strains in terms of their baseline immobility and responding to a specific drug5-11. For example, we identified differential antidepressant-like responses to lithium in a panel of mouse strains (Figure 1)5. Experimental details of this experiment are published in Can et al., 20115.
<img src="/files/ftp_upload/3638/3638fig1.jpg" alt="Bar graph comparing immobility time across mouse strains in response to saline treatments." data-altupdatedat="1747911167000" data-alt="Figure 1"> 
Figure 1. Immobility time (in seconds) in the forced swim test, five hours after a single i.p. injection of saline, 200, 300, or 400 mg/kg in various inbred and outbred mouse strains. *:p&lt;0.05, **:p&lt;0.01, ***:p&lt;0.001 denote a significant difference compared to saline group, Dunnett's post hoc test. Data are expressed as mean ± SEM. Number of animals per group for each strain is 6-8 (Figure reproduced from5).
Not all mouse strains are suitable for the FST. Some strains, such as Black Swiss, NIH Swiss, and FVB/NJ show little or almost no immobility under control conditions, therefore representing a floor effect (Figure 1)5. The lack of baseline immobility effectively prevents detecting an anti-depressant effect of experimental manipulations. It is also possible, while very rare, that some mouse strains may behave aberrantly and dive into the tank during the test even though they can float. One such strain is DBA/1OlaHsd (unpublished observation in our laboratory). Such strains are not suitable for the FST. Because of this diving risk, however small, when testing a new strain that has not been previously tested in the FST or a mouse harboring a novel genetic manipulation, it is imperative to carefully observe the initial trials to rescue mice if they engage in potentially harmful behaviors.
In the experimental design described here, multiple animals (up to five) are tested at the same time. While the dividers we use prevent mice from seeing each other during the test, and the white noise generator suppresses audible vocalizations, our set-up does not prevent all ultrasonic or olfactory cues from being transmitted. Though unlikely given the nature of the test, these could affect the behaviors of mice. One solution to this problem would be to test the animals individually. However, this approach has its own problems. For example, commonly, the animals tested in each session come from the same homecage. This allows randomization and counterbalancing of the experimental variables. Testing mice individually would mean removing one mouse at a time from the homecage. This will cause repeated stress and disturbance of social hierarchy in the cage among the others left behind. Another issue with testing singly are the time constraints. Testing one mouse at a time will extend the experiment into many hours resulting in a situation in which mice are tested at different times of the circadian cycle. This may create confounding time of day effects. The researchers should keep these issues in mind while designing their experiments.

<ol><li>Hascoét, M., Bourin, M. In Mood and Anxiety Related Phenotypes in Mice. 42, 85-118 (2009).</li>
<li>Sunal, R., Gümüçel, aB., Kayaalp, S. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+changes+in+swimming+area+on+results+of+%22behavioral+despair+test%22%5BTitle%5D)+AND+%22Pharmacology+Biochemistry+and+Behavior%22%5BJournal%5D)">Effect of changes in swimming area on results of "behavioral despair test".</a> Pharmacology Biochemistry and Behavior. 49, 891-896 (1994).</li>
<li>Petit-Demouliere, B., Chenu, F., Bourin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Forced+swimming+test+in+mice%3A+a+review+of+antidepressant+activity%5BTitle%5D)+AND+%22Psychopharmacology.+%28Berl%29%22%5BJournal%5D)">Forced swimming test in mice: a review of antidepressant activity.</a> Psychopharmacology. (Berl). 177, 245-255 (2005).</li>
<li>Cryan, J. F., Markou, A., Lucki, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assessing+antidepressant+activity+in+rodents%3A+recent+developments+and+future+needs%5BTitle%5D)+AND+%22Trends+in+Pharmacological+Sciences%22%5BJournal%5D)">Assessing antidepressant activity in rodents: recent developments and future needs.</a> Trends in Pharmacological Sciences. 23, 238-245 (2002).</li>
<li>Can, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Antidepressant-like+responses+to+lithium+in+genetically+diverse+mouse+strains%5BTitle%5D)+AND+%22Genes%2C+Brain+and+Behavior%22%5BJournal%5D)">Antidepressant-like responses to lithium in genetically diverse mouse strains.</a> Genes, Brain and Behavior. 10, 434-443 (2011).</li>
<li>Lucki, I., Dalvi, A., Mayorga, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sensitivity+to+the+effects+of+pharmacologically+selective+antidepressants+in+different+strains+of+mice%5BTitle%5D)+AND+%22Psychopharmacology.+%28Berl%29%22%5BJournal%5D)">Sensitivity to the effects of pharmacologically selective antidepressants in different strains of mice.</a> Psychopharmacology. (Berl). 155, 315-322 (2001).</li>
<li>David, D. J., Renard, C. E., Jolliet, P., Hascoet, M., Bourin, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Antidepressant-like+effects+in+various+mice+strains+in+the+forced+swimming+test%5BTitle%5D)+AND+%22Psychopharmacology+%28Berl%29%22%5BJournal%5D)">Antidepressant-like effects in various mice strains in the forced swimming test.</a> Psychopharmacology (Berl). 166, 373-382 (2003).</li>
<li>Bai, F., Li, X., Clay, M., Lindstrom, T., Skolnick, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Intra-+and+interstrain+differences+in+models+of+%22behavioral+despair%22%5BTitle%5D)+AND+%22Pharmacol.+Biochem.+Behav%22%5BJournal%5D)">Intra- and interstrain differences in models of "behavioral despair".</a> Pharmacol. Biochem. Behav. 70, 187-192 (2001).</li>
<li>Guzzetti, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Strain+differences+in+paroxetine-induced+reduction+of+immobility+time+in+the+forced+swimming+test+in+mice%3A+Role+of+serotonin%5BTitle%5D)+AND+%22European+Journal+of+Pharmacology%22%5BJournal%5D)">Strain differences in paroxetine-induced reduction of immobility time in the forced swimming test in mice: Role of serotonin.</a> European Journal of Pharmacology. 594, 117-124 (2008).</li>
<li>Cervo, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Genotype-dependent+activity+of+tryptophan+hydroxylase-2+determines+the+response+to+citalopram+in+a+mouse+model+of+depression%5BTitle%5D)+AND+%22J.+Neurosci%22%5BJournal%5D)">Genotype-dependent activity of tryptophan hydroxylase-2 determines the response to citalopram in a mouse model of depression.</a> J. Neurosci. 25, 8165-8172 (2005).</li>
<li>Jiao, J., Nitzke, A., Doukas, D., Seiglie, M., Dulawa, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Antidepressant+response+to+chronic+citalopram+treatment+in+eight+inbred+mouse+strains%5BTitle%5D)+AND+%22Psychopharmacology%22%5BJournal%5D)">Antidepressant response to chronic citalopram treatment in eight inbred mouse strains.</a> Psychopharmacology. 213, 509-520 (2011).</li>
<li>Porsolt, R. D., Pichon, M. L. e, Jalfre, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Depression%3A+a+new+animal+model+sensitive+to+antidepressant+treatments%5BTitle%5D)+AND+%22Nature%22%5BJournal%5D)">Depression: a new animal model sensitive to antidepressant treatments.</a> Nature. 266, 730-732 (1977).</li>
<li>Porsolt, R. D., Bertin, A., Jalfre, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Behavioral+despair+in+mice%3A+a+primary+screening+test+for+antidepressants%5BTitle%5D)+AND+%22Arch.+Int.+Pharmacodyn.+Ther%22%5BJournal%5D)">Behavioral despair in mice: a primary screening test for antidepressants.</a> Arch. Int. Pharmacodyn. Ther. 229, 327-336 (1977).</li>
<li>Porsolt, R. D., Bertin, A., Jalfre, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((%22Behavioural+despair%22+in+rats+and+mice%3A+strain+differences+and+the+effects+of+imipramine%5BTitle%5D)+AND+%22Eur.+J.+Pharmacol%22%5BJournal%5D)">"Behavioural despair" in rats and mice: strain differences and the effects of imipramine.</a> Eur. J. Pharmacol. 51, 291-294 (1978).</li>
<li>Mineur, Y. S., Belzung, C., Crusio, W. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+unpredictable+chronic+mild+stress+on+anxiety+and+depression-like+behavior+in+mice%5BTitle%5D)+AND+%22Behav.+Brain.+Res%22%5BJournal%5D)">Effects of unpredictable chronic mild stress on anxiety and depression-like behavior in mice.</a> Behav. Brain. Res. 175, 43-50 (2006).</li>
<li>Millstein, R. A., Holmes, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+repeated+maternal+separation+on+anxiety-+and+depression-related+phenotypes+in+different+mouse+strains%5BTitle%5D)+AND+%22Neuroscience+%26+Biobehavioral+Reviews%22%5BJournal%5D)">Effects of repeated maternal separation on anxiety- and depression-related phenotypes in different mouse strains.</a> Neuroscience & Biobehavioral Reviews. 31, 3-17 (2007).</li>
<li>Cryan, J. F., Valentino, R. J., Lucki, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assessing+substrates+underlying+the+behavioral+effects+of+antidepressants+using+the+modified+rat+forced+swimming+test%5BTitle%5D)+AND+%22Neuroscience+%26+Biobehavioral+Reviews%22%5BJournal%5D)">Assessing substrates underlying the behavioral effects of antidepressants using the modified rat forced swimming test.</a> Neuroscience & Biobehavioral Reviews. 29, 547-569 (2005).</li>
<li>Crowley, J. J., Jones, O. 'L. eary, F, O., Lucki, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Automated+tests+for+measuring+the+effects+of+antidepressants+in+mice%5BTitle%5D)+AND+%22Pharmacology+Biochemistry+and+Behavior%22%5BJournal%5D)">Automated tests for measuring the effects of antidepressants in mice.</a> Pharmacology Biochemistry and Behavior. 78, 269-274 (2004).</li>
<li>Kurtuncu, M., Luka, L. J., Dimitrijevic, N., Uz, T., Manev, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Reliability+assessment+of+an+automated+forced+swim+test+device+using+two+mouse+strains%5BTitle%5D)+AND+%22Journal+of+Neuroscience+Methods%22%5BJournal%5D)">Reliability assessment of an automated forced swim test device using two mouse strains.</a> Journal of Neuroscience Methods. 149, 26-30 (2005).</li>
<li>Hayashi, E., Shimamura, M., Kuratani, K., Kinoshita, M., Hara, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Automated+experimental+system+capturing+three+behavioral+components+during+murine+forced+swim+test%5BTitle%5D)+AND+%22Life+Sciences%22%5BJournal%5D)">Automated experimental system capturing three behavioral components during murine forced swim test.</a> Life Sciences. 88, 411-417 (2011).</li>
<li>Cryan, J., Page, M., Lucki, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Differential+behavioral+effects+of+the+antidepressants+reboxetine%2C+fluoxetine%2C+and+moclobemide+in+a+modified+forced+swim+test+following+chronic+treatment%5BTitle%5D)+AND+%22Psychopharmacology%22%5BJournal%5D)">Differential behavioral effects of the antidepressants reboxetine, fluoxetine, and moclobemide in a modified forced swim test following chronic treatment.</a> Psychopharmacology. 182, 335-344 (2005).</li>
<li>Gould, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Beta-catenin+overexpression+in+the+mouse+brain+phenocopies+lithium-sensitive+behaviors%5BTitle%5D)+AND+%22Neuropsychopharmacology%22%5BJournal%5D)">Beta-catenin overexpression in the mouse brain phenocopies lithium-sensitive behaviors.</a> Neuropsychopharmacology. 32, 2173-2183 (2007).</li>
<li>Can, A., Grahame, N. J., Gould, T. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Affect-related+related+behaviors+in+mice+selectively+bred+for+high+and+low+voluntary+alcohol+consumption%5BTitle%5D)+AND+%22Behav.+Genet%22%5BJournal%5D)">Affect-related related behaviors in mice selectively bred for high and low voluntary alcohol consumption.</a> Behav. Genet. , (2011).</li>
<li>McKinney, W. T., Bunney, W. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Animal+Model+of+Depression%3A+I+Review+of+Evidence%3A+Implications+for+Research.%5BTitle%5D)+AND+%22Arch.+Gen.+Psychiatry%22%5BJournal%5D)">Animal Model of Depression: I Review of Evidence: Implications for Research.</a> Arch. Gen. Psychiatry. 21, 240-248 (1969).</li>
<li>Willner, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((The+validity+of+animal+models+of+depression%5BTitle%5D)+AND+%22Psychopharmacology.%28Berl%29%22%5BJournal%5D)">The validity of animal models of depression.</a> Psychopharmacology.(Berl). 83, 1-16 (1984).</li>
<li>Detke, M. J., Lucki, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Detection+of+serotonergic+and+noradrenergic+antidepressants+in+the+rat+forced+swimming+test%3A+the+effects+of+water+depth%5BTitle%5D)+AND+%22Behav.+Brain+Res%22%5BJournal%5D)">Detection of serotonergic and noradrenergic antidepressants in the rat forced swimming test: the effects of water depth.</a> Behav. Brain Res. 73, 43-46 (1995).</li>
<li>Gould, T. D., Dao, D. T., Kovacsics, C. E. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aGould%2C+TD+%22In+Mood+and+Anxiety+Related+Phenotypes+in+mice%3A+characterization+using+behavioral+tests%22">In Mood and Anxiety Related Phenotypes in mice: characterization using behavioral tests</a>. Gould, T. D. 42, Humana Press. (2009).</li>
<li>Bourin, M., Fiocco, A. J., Clenet, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((How+valuable+are+animal+models+in+defining+antidepressant+activity%5BTitle%5D)+AND+%22Human+Psychopharmacology%3A+Clinical+and+Experimental%22%5BJournal%5D)">How valuable are animal models in defining antidepressant activity.</a> Human Psychopharmacology: Clinical and Experimental. 16, 9-21 (2001).</li>
</ol>

Authors declare no conflicts of interest.

The FST (sometimes called Porsolt swim test) was developed first for rats and then modified for mice by Porsolt and colleagues12,13. In addition to the above-described protocol successful in our laboratory, a number of largely subtle test modifications have been published (see Hasco&euml;t and Bourin for a complete review1). It is a common test used for evaluation of the efficacy of anti-depressant drugs and the effects of various behavioral and neurobiological manipulations in basic and preclinical...

<table><tbody><tr><td>Water tanks</td><td></td><td></td><td></td></tr><tr><td>Thermometer</td><td></td><td></td><td></td></tr><tr><td>Timer</td><td></td><td></td><td></td></tr><tr><td>Video Camera</td><td></td><td></td><td></td></tr><tr><td>White Noise Generator (optional)</td><td></td><td></td><td></td></tr><tr><td>Drying Paper</td><td></td><td></td><td></td></tr></tbody></table>

the mouse forced swim test

The forced swim test is a rodent behavioral test used for evaluation of antidepressant drugs, antidepressant efficacy of new compounds, and experimental manipulations that are aimed at rendering or preventing depressive-like states. Mice are placed in an inescapable transparent tank that is filled with water and their escape related mobility behavior is measured. The forced swim test is straightforward to conduct reliably and it requires minimal specialized equipment. Successful implementation of the forced swim test requires adherence to certain procedural details and minimization of unwarranted stress to the mice. In the protocol description and the accompanying video, we explain how to conduct the mouse version of this test with emphasis on potential pitfalls that may be detrimental to interpretation of results and how to avoid them. Additionally, we explain how the behaviors manifested in the test are assessed.

Watch this Scientific Journal Video about The Mouse Forced Swim Test at JoVE.com

The Mouse Forced Swim Test

The forced swim test is validated as an experimental approach to assess potential antidepressant efficacy in rodents. Experimental animals are placed in a tank of water and escape-related mobility behavior is quantified. The common procedures for the mouse version of this test are described.

The forced swim test is a rodent behavioral test used for evaluation of antidepressant drugs, antidepressant efficacy of new compounds, and experimental ...

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105.2K Views.  University of Maryland School of Medicine. The forced swim test is validated as an experimental approach to assess potential antidepressant efficacy in rodents. Experimental animals are placed in a tank of water and escape-related mobility behavior is quantified. The common procedures for the mouse version of this test are described.

Video: The Mouse Forced Swim Test

Shallow Water (Paddling) Variants of Water Maze Tests in Mice

When Richard Morris devised his water maze in 19817, most behavioral work was done in rats. However, the greater understanding of mouse genetics led to the mouse becoming increasingly important. But researchers found that some strains of mutant mice were prone to problems like passively floating or diving when they were tested in the Morris water maze11. This was unsurprising considering their natural habitat; rats swim naturally (classically, the "sewer rat"), whereas mice evolved in the dry areas of central Asia.
To overcome these problems, it was considered whether shallow water would be a sufficient stimulus to provide escape motivation for mice. This would also avoid the problems of drying the small creatures with a towel and then putting them in a heated recovery chamber to avoid hypothermia, which is a much more serious problem than with rats; the large ratio of surface area to volume of a mouse makes it particularly vulnerable to rapid heat loss.
Another consideration was whether a more natural escape strategy could be used, to facilitate learning. Since animals that fall into water and swim away from the safety of the shore are unlikely to pass on their genes, animals have evolved a natural tendency to swim to the edge of a body of water. The Morris water maze, however, requires them to swim to a hidden platform towards the center of the maze - exactly opposite to their evolved behavior. Therefore the paddling maze should incorporate escape to the edge of the apparatus. This feature, coupled with the use of relatively non-aversive shallow water, embodies the "Refinement" aspect of the "3 Rs" of Russell and Burch8.
Various types of maze design were tried; the common feature was that the water was always shallow (2 cm deep) and escape was via a tube piercing the transparent wall of the apparatus. Other tubes ("false exits") were also placed around the walls but these were blocked off. From the inside of the maze all false exits and the single true exit looked the same. Currently a dodecagonal (12-sided) maze is in use in Oxford, with 12 true/false exits set in the corners. In a recent development a transparent paddling Y-maze has been tested successfully.

Shallow Water Paddling Variants of Water Maze Tests in Mice

Mice can swim, but many strains appear to find this activity stressful. To overcome this problem mazes have been devised where escape from shallow water is used to motivate behaviour. These have been demonstrated to support learning at least as good as the traditional and widely used Morris water maze.

When Richard Morris devised his water maze in 19817, most behavioral work was done in rats. However, the greater understanding of mouse genetics led to ...

Behavior

The Forced Swim Test as a Model of Depressive-like Behavior

The goal of the present protocol is to describe the forced swim test (FST), which is one of the most commonly used assays for the study of depressive-like behavior in rodents. The FST is based on the assumption that when placing an animal in a container filled with water, it will first make efforts to escape but eventually will exhibit immobility that may be considered to reflect a measure of behavioral despair. This test has been extensively used because it involves the exposure of the animals to stress, which was shown to have a role in the tendency for major depression. Additionally, the FST has been shown to share some of the factors that are influenced or altered by depression in humans, including changes in food consumption, sleep abnormalities and drug-withdrawal-induced anhedonia. The main advantages of this procedure are that it is relatively easy to perform and that its results are easily and quickly analyzed. Moreover, its sensitivity to a broad range of antidepressant drugs that makes it a suitable screening test is one of the most important features leading to its high predictive validity. Despite its appeal, this model has a number of disadvantages. First, the issue of chronic augmentation is problematic in this test because in real life patients need to be treated for at least several weeks before they experience any relief from their symptoms. Last, due to the aversiveness of the FST, it is important to take into account possible influences it might have on brain structure/function if brain analyses are to be carried out following this procedure.

This protocol describes the forced swim test, which is used for the study of depressive-like behavior in rodents. This procedure involves placing an animal in a container filled with water that eventually will lead to the exhibition of immobility behavior, which is considered to reflect behavioral despair.

The goal of the present protocol is to describe the forced swim test (FST), which is one of the most commonly used assays for the study of depressive-like ...

Applying Stereotactic Injection Technique to Study Genetic Effects on Animal Behaviors

Stereotactic injection is a useful technique to deliver high titer lentiviruses to targeted brain areas in mice. Lentiviruses can either overexpress or knockdown gene expression in a relatively focused region without significant damage to the brain tissue. After recovery, the injected mouse can be tested on various behavioral tasks such as the Open Field Test (OFT) and the Forced Swim Test (FST). The OFT is designed to assess locomotion and the anxious phenotype in mice by measuring the amount of time that a mouse spends in the center of a novel open field. A more anxious mouse will spend significantly less time in the center of the novel field compared to controls. The FST assesses the anti-depressive phenotype by quantifying the amount of time that mice spend immobile when placed into a bucket of water. A mouse with an anti-depressive phenotype will spend significantly less time immobile compared to control animals. The goal of this protocol is to use the stereotactic injection of a lentivirus in conjunction with behavioral tests to assess how genetic factors modulate animal behaviors.

Stereotactic injection of lentiviruses expressing cDNAs or shRNAs can modulate gene expression in specific brain areas of mice. Here, we present a protocol to combine stereotactic injections with behavioral tasks, such as the Open Field Test (OFT) and the Forced Swim Test (FST).

Stereotactic injection is a useful technique to deliver high titer lentiviruses to targeted brain areas in mice. Lentiviruses can either overexpress or ...

The Double-H Maze: A Robust Behavioral Test for Learning and Memory in Rodents

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their behavioral flexibility and required memory duration, the number of goals and pathways, and also the overall task complexity. A confounding feature in many of these tasks is the lack of control over the strategy employed by the rodents to reach the goal, e.g., allocentric (declarative-like) or egocentric (procedural) based strategies. The double-H maze is a novel water-escape memory task that addresses this issue, by allowing the experimenter to direct the type of strategy learned during the training period. The double-H maze is a transparent device, which consists of a central alleyway with three arms protruding on both sides, along with an escape platform submerged at the extremity of one of these arms.
Rats can be trained using an allocentric strategy by alternating the start position in the maze in an unpredictable manner (see protocol 1; &#167;4.7), thus requiring them to learn the location of the platform based on the available allothetic cues. Alternatively, an egocentric learning strategy (protocol 2; &#167;4.8) can be employed by releasing the rats from the same position during each trial, until they learn the procedural pattern required to reach the goal. This task has been proven to allow for the formation of stable memory traces.
Memory can be probed following the training period in a misleading probe trial, in which the starting position for the rats alternates. Following an egocentric learning paradigm, rats typically resort to an allocentric-based strategy, but only when their initial view on the extra-maze cues differs markedly from their original position. This task is ideally suited to explore the effects of drugs/perturbations on allocentric/egocentric memory performance, as well as the interactions between these two memory systems.

The goal of this protocol is to investigate spatial cognition in rodents. The double-H water maze is a novel test, which is particularly useful to elucidate the different components of learning, consolidation and memory, as well as the interplay of memory systems.

Spatial cognition research in rodents typically employs the use of maze tasks, whose attributes vary from one maze to the next. These tasks vary by their ...

Morris Water Maze Test: Optimization for Mouse Strain and Testing Environment

The Morris water maze (MWM) is a commonly used task to assess hippocampal-dependent spatial learning and memory in transgenic mouse models of disease, including neurocognitive disorders such as Alzheimer&#8217;s disease. However, the background strain of the mouse model used can have a substantial effect on the observed behavioral phenotype, with some strains exhibiting superior learning ability relative to others. To ensure differences between transgene negative and transgene positive mice can be detected, identification of a training procedure sensitive to the background strain is essential. Failure to tailor the MWM protocol to the background strain of the mouse model may lead to under- or over- training, thereby masking group differences in probe trials. Here, a MWM protocol tailored for use with the F1 FVB/N x 129S6 background is described. This is a frequently used background strain to study the age-dependent effects of mutant P301L tau (rTg(TauP301L)4510 mice) on the memory deficits associated with Alzheimer&#8217;s disease. Also described is a strategy to re-optimize, as dictated by the particular testing environment utilized.

This manuscript describes a Morris water maze (MWM) protocol tailored for use with a commonly used mouse model of Alzheimer's disease. The MWM is widely used in transgenic mouse models. Implementation of a procedure sensitive to the background strain of the mouse model is essential for detecting group differences.

 The Morris water maze (MWM) is a commonly used task to assess hippocampal-dependent spatial learning and memory in transgenic mouse models of disease, ...

Morris Water Maze Test for Learning and Memory Deficits in Alzheimer&#39;s Disease Model Mice

The Morris Water Maze (MWM) was first established by neuroscientist Richard G. Morris in 1981 in order to test hippocampal-dependent learning, including acquisition of spatial memoryand long-term spatial memory 1. The MWM is a relatively simple procedure typically consisting of six day trials, the main advantage being the differentiation between the spatial (hidden-platform) and non-spatial (visible platform) conditions 2-4. In addition, the MWM testing environment reduces odor trail interference 5. This has led the task to be used extensively in the study of the neurobiology and neuropharmacology of spatial learning and memory. The MWM plays an important role in the validation of rodent models for neurocognitive disorders such as Alzheimer&#x2019;s Disease 6, 7. In this protocol we discussed the typical procedure of MWM for testing learning and memory and data analysis commonly used in Alzheimer&#x2019;s disease transgenic model mice.

Morris Water Maze Test for Learning and Memory Deficits in Alzheimer's Disease Model Mice

The Morris Water Maze is a behavioral task to test hippocampal-dependent learning and memory. It has been widely used in the study of neurobiology, neuropharmacology and neurocognitive disorders in rodent models.

The Morris Water Maze (MWM) was first established by neuroscientist Richard G. Morris in 1981 in order to test hippocampal-dependent learning, including ...

T-maze Forced Alternation and Left-right Discrimination Tasks for Assessing Working and Reference Memory in Mice

Forced alternation and left-right discrimination tasks using the T-maze have been widely used to assess working and reference memory, respectively, in rodents. In our laboratory, we evaluated the two types of memory in more than 30 strains of genetically engineered mice using the automated version of this apparatus. Here, we present the modified T-maze apparatus operated by a computer with a video-tracking system and our protocols in a movie format. The T-maze apparatus consists of runways partitioned off by sliding doors that can automatically open downward, each with a start box, a T-shaped alley, two boxes with automatic pellet dispensers at one side of the box, and two L-shaped alleys. Each L-shaped alley is connected to the start box so that mice can return to the start box, which excludes the effects of experimenter handling on mouse behavior. This apparatus also has an advantage that in vivo microdialysis, in vivo electrophysiology, and optogenetics techniques can be performed during T-maze performance because the doors are designed to go down into the floor. In this movie article, we describe T-maze tasks using the automated apparatus and the T-maze performance of &alpha;-CaMKII+/- mice, which are reported to show working memory deficits in the eight-arm radial maze task. Our data indicated that &alpha;-CaMKII+/- mice showed a working memory deficit, but no impairment of reference memory, and are consistent with previous findings using the eight-arm radial maze task, which supports the validity of our protocol. In addition, our data indicate that mutants tended to exhibit reversal learning deficits, suggesting that &alpha;-CaMKII deficiency causes reduced behavioral flexibility. Thus, the T-maze test using the modified automatic apparatus is useful for assessing working and reference memory and behavioral flexibility in mice.

This article presents the protocol of T-maze tests using a modified automated apparatus for assessing the learning and memory functions in mice.

Forced alternation and left-right discrimination tasks using the T-maze have been widely used to assess working and reference memory, respectively, in ...

The Tail Suspension Test

The tail-suspension test is a mouse behavioral test useful in the screening of potential antidepressant drugs, and assessing of other manipulations that are expected to affect depression related behaviors. Mice are suspended by their tails with tape, in such a position that it cannot escape or hold on to nearby surfaces. During this test, typically six minutes in duration, the resulting escape oriented behaviors are quantified. The tail-suspension test is a valuable tool in drug discovery for high-throughput screening of prospective antidepressant compounds. Here, we describe the details required for implementation of this test with additional emphasis on potential problems that may occur and how to avoid them. We also offer a solution to the tail climbing behavior, a common problem that renders this test useless in some mouse strains, such as the widely used C57BL/6. Specifically, we prevent tail climbing behaviors by passing mouse tails through a small plastic cylinder prior to suspension. Finally, we detail how to manually score the behaviors that are manifested in this test.

The tail-suspension test is validated as an experimental procedure to assess antidepressant efficacy of drug treatments in mice. Mice are suspended by their tails for six minutes and escape-related behaviors are assessed. We describe procedures used in conducting the tail suspension test.

The tail-suspension test is a mouse behavioral test useful in the screening of potential antidepressant drugs, and assessing of other manipulations that ...

A Behavioral Test Battery for the Repeated Assessment of Motor Skills, Mood, and Cognition in Mice

Pharmacological and toxicological studies in neurodegeneration require comprehensive behavioral analysis in mice because motor dysfunctions and dysfunctions in mood and cognition are common and often shared symptoms in neurodegenerative diseases. Shown here is a behavioral test battery for motor, mood, and cognition, which can be repeatedly tested in a longitudinal study. This battery assesses the overall behavioral phenotype in mice by examining each domain of behavior with at least two independent well-accepted tests (i.e., open-field test and rotarod test for motor function, social interaction test, elevated plus maze test, and forced swim test for emotional function, and Morris water maze test and novel object recognition test for cognitive function). Therefore, this sensitive and comprehensive test battery is a powerful tool for the study of behavioral alternation in neurodegeneration.

A comprehensive behavioral test battery of motor skills, mood&#8212;including social interaction, depression, and anxiety&#8212;and cognition is designed for the repeated assessment of neurodegeneration-related behavioral changes in mice.

Pharmacological and toxicological studies in neurodegeneration require comprehensive behavioral analysis in mice because motor dysfunctions and ...

The Mouse Stroke Unit Protocol with Standardized Neurological Scoring for Translational Mouse Stroke Studies

The filament model of middle artery occlusion (fMCAo) is perhaps the most translational mouse stroke model, allowing for controlled ischemia with intravascular reperfusion/recanalization. However, it lacks alignment with current clinical advances for stroke care (e.g., Stroke Units), usually employs subjective or vague neurological scoring among laboratories, and exhibits high acute-phase mortality. Here, we address these limitations with validated video-guided protocols. We present the mouse Stroke Unit (mSU) protocol with instructional videos and a decision algorithm (Risk Stratification Score), bridging the gap between clinical and mouse stroke modeling. To increase accuracy and sensitivity of stroke neurological scoring, we present for the first time a video-standardized format of the focal Experimental Stroke Scale (fESS) and prove its value up to 6 months post-stroke. Additionally, protocols for mice Ladder-rung test, as well as the known Cylinder test, for unbiased, quantitative assessment of limbs&#180; motor function are presented. Results highlight mSU&#39;s translational efficacy. Focal ESS (fESS) excels over other known scales in detecting focal stroke deficits, capturing recovery, and maintaining sensitivity for up to 6 months post-stroke. Ladder-rung and Cylinder tests objectively quantify and monitor fore- and hind-limb motor deficits, long-term. In summary, integrating mSU, fESS, and motor function tests provides a robust framework for clinically relevant stroke investigations. Our protocols improve the translational value in mouse stroke research.

This article presents a protocol for executing the highly translational and independently proven mouse Stroke Unit (mSU) concept in large-stroke mice. It also provides a standardized protocol for executing the focal experimental stroke scale in mice, which evaluates stroke focal deficits detected even long-term.