Genes2Cognition

Documentation - Behaviour Data

This is the documentation for the behaviour data in the G2Cdb. Click on one of the field headings below, or just scroll down to browse the available information.

Summary
The behaviour section of the G2Cdb summarises the literature on the behavioural phenotypes of knockout mice.
Much of the data is derived from a systematic literature curation, covering 518 papers. Of these, 167 papers have been curated in detail. These 167 papers study a total of 123 genes.
For each experiment we provide information on the nature of the genetic modification used and some other background, before proceeding to a detailed annotation of the behavioural phenotype observed. Summaries are provided for reported studies of perceptual and motor abilities, as well as tests designed to assess their emotional state (particularly their level of behavioural anxiety).
However, G2C's main area of interest is learning and memory, and these areas of study are given a particularly detailed analysis. A wide range of different learning tests is included in the database, and in some cases have been separated into their component stages for an even more detailed analysis. Furthermore, the learning and memory tests have been grouped according to the brain region within which the learning process is thought to occur. The classifications are quite broad, reflecting the difficulties with attributing a cognitive process to a clearly delineated brain region. References providing evidence for the given attributions are given in the documentation for each test. The brain regions are listed in the table below. For details of brain anatomy, see the Allen Brain Atlas.

Brain regions
Cerebellum
Amygdala
Hippocampus
Striatum
Multiple or Undetermined Brain Regions

Classification of Phenotypes
For each behavioural test reported, the phenotype is described according to a two-step system. To allow a simple display, the classifications have been assigned codes.
In the first step, the behaviour report is classified as either normal, impaired or enhanced. For a classification to be assigned, a statistical test must have been performed on the data and a significant difference reported - any data that have not been statistically analysed are included as Anecdotal Observations.
The classification codes are shown in this table:

Basic Phenotypes
Classification	Code
Impaired	imp
Enhanced	enh
Normal	nor

Secondly, further information about the nature of the behavioural effect is provided. This can be quite complex, reflecting the intricacy of behavioural science. For example:

Many studies investigate how the mice acquire a task (learning), i.e. how or if they improve over a series of repeated attempts. Acquisition can be assessed in two different ways. Firstly, the mutant and control mice can each be given the same number of trials and (typically) be compared at the end of this training. Alternatively, the experimenter may decide to use a particular criterion of performance and then train the mice until they achieve this criterion - the mice can then be assessed on whether they manage to reach this criterion, and whether there are differences between the mutant and control mice in the number of trials required. Each of these possibilities is included in our classification system.
If retention of a particular task is tested following training (assessing memory), this can require the animal to use different memory systems depending on the retention interval. Hence, we have classified such behaviours as 'short-term', 'intermediate-term', 'long-term' and 'very-long-term' memory according to the retention interval. We do not claim that the classifications we have used reflect different memory systems; rather, they reflect the different intervals generally used by behavioural geneticists.
A further set of possibilities arises when the experimenters compare performance of mutant mice to control mice on a test, when another variable is introduced. For instance, it is reasonably common for experimenters to vary the environment in which the mice live (perhaps by enriching it with stimuli), as this is known to have an effect on their ability to learn. If a particular environmental manipulation improves learning in the control mice, but has no effect on the mutants, then the mutants are classified as being 'impaired with respect to environment', or 'imp envi'. Analogous statements are made for experiments that give the mice drugs or hormones, or vary their diet, stress levels or age.
The mouse might fail a task in a range of different ways; perhaps by using the wrong strategy to solve it.

The complete list of classifications that we have used are given in the table below. Following on from this, some 'worked examples' are also given.

Details of Phenotypes
Classification	Code
General/No Details Supplied	ns
Acquisition Over a Fixed Number of Trials	acqfn
Acquisition to a Pre-Defined Criterion (mouse fails to do so)	acqcr
Acquisition to a Pre-Defined Criterion (delayed)	dacqcr
Short-Term Memory (less than 24 hours)	stm
Intermediate-Term Memory (1-3 days)	itm
Long-Term Memory (4-10 days)	ltm
Very-Long-Term Memory (over 10 days)	vltm
Consolidation	con
Latent Learning	lat
Strategy Choice	stch
With Respect to Drug	drug
With Respect to Hormone	hor
With Respect to Time of Day	tod
With Respect to Age	age
With Respect to Stress Levels	stress
With Respect to Diet	diet
With Respect to Environment	envi
With Respect to Lesion	les

Here are some examples of entries, and what they mean:

imp acqfn - the mutant mice and control mice have been given the same number of training trials to acquire a task, and the mutant mice have performed worse than the control mice over the course of these trials.
nor stm - the mutant and control mice have been tested for their retention of a task, less than 24 hours after their last training trial. There is no statistical difference between the two groups' performance.
enh stch - the mutant mice have used a better strategy to solve the task compared to the control mice.
imp ns - the mutant mice are impaired compared to the control mice. No further information can be supplied about the nature of their impairment - this may be because the description in the original paper was vague, or simply that none of our additional classifications apply. The latter is generally the case with tests of perception, motor control and emotional state, as our classifications are targeted principally at tests of learning and memory.

Some good general references on behavioural phenotyping of knockout mice are:

10448192, Crawley JN, 'Behavioral phenotyping of transgenic and knockout mice: experimental design and evaluation of general health, sensory functions, motor abilities, and specific behavioral tests', Brain Res, 1999 Jul 17; 835(1): 18-26.
Eumorphia, an integrated research programme focused on phenotyping, mutagenesis and bioinformatics.

Citation

Reference
The full citation for the paper. The authors, title, journal name, issue, volume and year are given.

PubMed ID
The PubMed ID for the paper. The ID acts as a link to the paper's entry on PubMed.

Experiment number
A single paper may contain more than one genetic experiment, for instance knockout of two or more genes, or knocking out a gene in different brain regions. Each such experiment is assigned a number (generally reflecting the order in which they are reported in the paper), to serve as an identifier. For each such genetic manipulation, all the individual behavioural tests performed are stored within that one experiment.

Gene
The common gene name.

Mutation type
The type of mutation the gene has been subjected to in the paper. Mutations were classified as belonging to one of the following categories:

Mutation type Code

Knockout ko

Over-Expression ov

Point po

Truncation tr

Conditional co

Other ot

Tissue
The brain region(s) in which the gene was knocked out (or otherwise mutated). Typically mutations are 'global', meaning that the gene is mutated in all regions of the brain. In recent years technology has been developed enabling genes to be knocked out in limited areas of the brain, for example the forebrain or the hippocampus; in such cases, the affected area is specified.

Zygosity
Mouse are diploid organisms, meaning that their chromosomes come in pairs (such chromosomes are called autosomes). The animals therefore have two chromosomal copies of all their autosomal genes. A mutation in an autosomal gene may thus be homozygous (also known as HOMO, null mutant or -/-), meaning that it is present in both copies, or heterozygous (also referred to as HET or -/+), meaning that only one of the gene copies contains the mutation.
A third possibility occurs in males, which have non-identical sex chromosomes: they have one X and one Y chromosome, whereas the females have two X chromosomes. Genes present on the X or Y chromosome in males are present in one copy only, and mutations in such genes are referred to as hemizygous (also referred to as HEMI or -/Y). Sex chromosomes are also referred to as heterosomes.
The tables below summarise the different scenarios that arise in male and female mice.

Male
Mutation in 1 copy Mutation in 2 copies
Autosomal Hetero Homo
Heterosomal Hemi N/A

Female
Mutation in 1 copy Mutation in 2 copies
Autosomal Hetero Homo
Heterosomal Hetero Homo

Mouse strain
The strain of mice used as the basis of the genetic experiments. Two typical laboratory strains are C57Bl/6J and 129S5. Where strains have been crossed, it is indicated thus: 'C57Bl/6J x 129S5'. If embryonic stem cells were used as a vehicle for carrying a mutation, this is also indicated here, as is the strain of mice from which the ES cells were derived.
A detailed guide to official mouse strain nomenclature can be found here; our descriptions follow these guidelines as far as possible, but in some cases (particularly regarding crossed strains) it is not possible to define the strain to this level of detail, due to a paucity of description in the source paper.

Backcrosses/Intercrosses
Two descriptions of the breeding programme used to generate the mice. Backcrossing is the process of mating a hybrid animal (e.g. C57BL/6J x 129S5)with an animal of the same strain as one of its parents (e.g. C57BL/6J). The number of backcrosses is represented using the letter N, so for example an entry of N5 would mean that the hybrid line has been backcrossed five times.
Intercrossing is the process of breeding hybrid animals using brother-sister mating pairs. The number of intercrosses is represented using the letter F, so for example an entry of F3 would mean that the hybrid line has been intercrossed three times.

Mouse supplier details
Details of the individual/organisation that supplied the mice to the experimenters. Many authors only note that they used the same strain of mice used 'previously', in which case we supply details of the original paper, including a PubMed link.

Control mice
Details of the control mice used. Were they littermates of the experimental animals or unrelated? Were they wild-type, heterozygous or some other zygosity?

Battery testing or Experimentally Naive?
Were all mice used for all behavioural tests (a battery), or were separate groups of mice used for each test (naive)? This information is only rarely supplied in the literature.

General Observations

Anecdotal observation
Observations noted in the paper that do not have quantitative experimental evidence to support them. Typical observations are that the mice 'appear grossly normal', engage in normal behaviours such as nesting, and are able to eat and drink.

Weight
The average weight of the mutant mice, in grams, compared to the control mice.

Size
The average size (measured as length in centimetres) of the mutant mice compared to the control mice.

Age
The age of the mice, in days, when they began behavioural testing.

Sex
The sex(es) of the mice used for behavioural testing. In some cases experimenters use a mixture of male and female in both the mutant and control groups, but ensure that the two groups have the same proportion of male and female mice: such cases are marked as 'matched'.

Developmental landmarks
Any information given in the paper about changes to the mutants' ability to reach key developmental landmarks compared to the control mice.

Physiology (non-neural)
Any information given in the paper about changes to the mutants' physiology compared to the control mice.

Neurophysiology
Any information given in the paper about changes to the mutants' neurophysiology compared to the control mice.

Perceptual Tests

An excellent resource for tests of vision, hearing and balance is Steel KP, Hardisty R, Assessing Hearing, Vision and Balance in Mice, 1996, Washington, DC: Society of Neuroscience.

Vision
Results of vision tests.
A typical test is the visual cliff, in which the mice are placed on a surface painted so as to give the impression that there is a large cliff down which they might fall. Mice with functional vision tend to stay away from the visual cliff. Two early descriptions of the visual cliff can be found in 13442652, Walk RD, Gibson EJ, Tighe TJ, 'Behavior of light- and dark-reared rats on a visual cliff', Science, 1957 Jul 12; 126(3263): 80-1, and 5835839, Fox MW, 'The visual cliff test for the study of visual depth perception in the mouse', Anim Behav, 1965 Apr-Jul; 13(2): 232-3.
Another test of vision is eye closure reflex to approaching objects. In this test an object, typically a rubber rod, approaches the mice from above and is halted about 1cm from their eyes. Mice with normal vision will tend to reflexively close their eyes in response to the approaching object. The test is described in 10680758, Gerlai R, Thibodeaux H, Palmer JT, van Lookeren Campagne M, Van Bruggen N, 'Transient focal cerebral ischemia induces sensorimotor deficits in mice', Behav Brain Res, 2000 Feb; 108(1): 63-71.
More advanced tests use custom-built software to produce stimuli that the mouse must discriminate. An illustrative video, and further information, can be found on the Cerebral Mechanics website (the video requires QuickTime).

Hearing
Tests of hearing; two widely-used tests are acoustic startle and the Preyer reflex.

In acoustic startle, sounds of different intensities are played to the mouse in a small chamber and their startle response is measured. Mice with functional hearing tend to startle to loud noises, whereas hearing impaired mice do not. An early description of acoustic startle can be found in Prosser CL, Hunter WS, 'The extinction of startle responses and spinal reflexes in the white rat', Am J Physiol, 1936; 117: 609-618. For a detailed analysis, see 7086484, Davis M, Gendelman DS, Tischler MD, Gendelman PM, 'A primary acoustic startle circuit: lesion and stimulation studies', J Neurosci, 1982 Jun; 2(6): 791-805. The acoustic startle procedure is also the basis for tests of Pre-pulse inhibition.
A similar test is the Preyer reflex (one-click response), which looks for a reflexive ear-twitch in response to a sudden sound such as a hand clap. The Preyer reflex was first described in Preyer W, 'Die Seele des Kindes', 1882 (Grleben-Verlag, Leipzig, Germany). A detailed analysis of the test is presented in 11583390, Jero J, Coling DE, Lalwani AK, 'The use of Preyer's reflex in evaluation of hearing in mice', Acta Otolaryngol, 2001 Jul; 121(5): 585-9.

Olfaction
Tests of olfactory abilities (sense of smell); several procedures can be used.

A widely-used test is Habituation/Dishabituation, which tests the mice's ability to discriminate between two different odours. The odours are presented on an applicator such as a cotton-wool bud. A typical procedure is to give the mouse multiple trials of three odours each. The first is simply water (odourless), followed by two different strong smells (for instance cinnamon and cocoa) in random order. If the mouse can discriminate, it should show the same level of sniffing behaviour to the second odour as the first; however, if it cannot discriminate them, it should habituate to the first odour and thus pay little attention to the second. Good descriptions of the test can be found in 3174848, Brown RE, 'Individual odors of rats are discriminable independently of changes in gonadal hormone levels', Physiol Behav, 1988; 43(3): 359-63, and 12031548, Luo AH, Cannon EH, Wekesa KS, Lyman RF, Vandenbergh JG, Anholt RR, 'Impaired olfactory behavior in mice deficient in the alpha subunit of G(o)', Brain Res, 2002 Jun 21; 941 (1-2): 62-71.
A commonly-used test is the buried cookie test. For this, the mouse is habituated to a test cage with a deep layer of bedding all over the floor, then removed from the test cage. An odour-rich reward, for example a cookie, is then buried in the bedding layer. The mouse is then returned to the cage, and the experimenter records the time taken to find the reward. The test was first described in 5149455, Alberts JR, Galef BG Jr, 'Acute anosmia in the rat: a behavioral test of a peripherally-induced olfactory deficit', Physiol Behav, 1971 May; 6(5): 619-21.
An alternative procedure is to give mice the choice between 'attractive' bedding from their own cage and 'repellent' bedding that has been treated with an unappealing substance such as lemon juice. Mice that can smell will generally choose the bedding with the pleasant smell. The test was first described in 938408, Cornwell CA, 'Selective olfactory exposure alters social and plant odor preferences of immature hamsters', Behav Biol, 1976 May; 17(1): 131-7.

Pain
Tests of response to painful stimuli. Such tests include hotplate, tail-flick, shock sensitivity, writhing and formalin-induced inflammation of the paw. Good reviews of pain tests, discussing the appropriateness and value of the various methods, can be found in 11682095, Wilson SG, Mogil JS, 'Measuring pain in the (knockout) mouse: big challenges in a small mammal', Behav Brain Res, 2001 Nov 1; 125(1-2): 65-73, and 15494180, Mogil JS, Crager SE, 'What should we be measuring in behavioral studies of chronic pain in animals?', Pain, 2004 Nov; 112(1-2): 12-5.

In the hotplate test, the mouse is placed on a warmed surface. A typical measure of sensitivity to pain is the time they wait before licking their rear paw. The temperature of the hotplate may also be varied, but is typically 55^oC. A key early reference on the hotplate test is 1168252, O'Callaghan JP, Holtzman SG, 'Quantification of the analgesic activity of narcotic antagonists by a modified hot-plate procedure', J. PharmacoL exp. Ther., 1975; 192: 497-505.
In the tail-flick test, a radiant source of heat is focused on the mouse's tail. The time taken for the mouse to move (flick) its tail away from the heat is considered to be a measure of its sensitivity. The tail-flick test was first described in D'Amour FE, Smith DL, 'A method for determining loss of pain sensation', J. PharmacoL exp. Ther., 1941; 72: 74-79 (not available online). A typical apparatus is described in 4549764, Mayer DJ, Liebeskind JC, 'Pain reduction by focal electric stimulation of the brain: an anatomical and behavioral analysis', Brain Research, 1974; 68: 73-93. The test was modified somewhat in the late 1980s: this literature can be traced from 2293148, Hole K, Berge OG, Tjolsen A, Eide PK, Garcia-Cabrera I, Lund A, Rosland JH, 'The tail-flick test needs to be improved', Pain, 1990 Dec; 43(3): 391-3.
A third test is to subject the mouse to electrical shocks of varying intensity and record what level of shock is required to elicit a response such as a jump, flinch or squeak. This is a shock sensitivity test, also known as the flinch-jump test. The test was first described in Evans WO, 'A new technique for the investigation of some analgesic drugs on a reflexive behavior in the rat', Psychopharmacology, 1961; 2(5): 318-325 (available through SpringerLink). A good description can be found in 16707171, Lehner M, Taracha E, Skorzewska A, Maciejak P, Wislowska-Stanek A, Zienowicz M, Szyndler J, Bidzinski A, Plaznik A, 'Behavioral, immunocytochemical and biochemical studies in rats differing in their sensitivity to pain', Behav Brain Res, 2006 Aug 10; 171(2): 189-98.
Writhing, also known as abdominal constriction, involves injecting the animal with a pain-inducing substance such as acetic acid. The experimenter then observes the number of 'writhes' (abdominal constrictions) the mouse engages in. A typical writhe consists of a stretching of the whole animal so that it looks elongated. The abdomen touches the surface; there is also torsion to one side, drawing up of the hind limbs and usually 'sucking in' of the abdomen. The test was first described in 4230818, Collier HOJ, Dinneen LC, Johanson CA, Scheider C, 'The abdominal constriction response and its suppression by analgesic drugs in the mouse', Br J Pharmacol Chemother, 1968, 32; 295-310. An excellent description can be found in 7865865, Adachi K, 'A device for automatic measurement of writhing and its application to the assessment of analgesic agents', J Pharmacol Toxicol Methods, 1994 Oct; 32(2): 79-84.
The formalin paw test uses a mouse's response to a longer-lasting form of acute pain. A small bolus of formalin is injected into the mouse's paw, causing inflammation. In humans, the sensation is one of burning, throbbing pain. The pain response generally lasts approximately 30 minutes. The mouse's behaviour is observed throughout, and the experimenter records the amount of time spent doing a number of things, e.g. licking the paw, biting it, elevating it or reducing the weight put on it, all of which are taken as indicative of the amount of pain being experienced. The original formalin paw paper is 564014, Dubuisson D, Dennis SG, 'The formalin test: a quantitative study of the analgesic effects of morphine, meperidine, and brain stem stimulation in rats and cats', Pain, 1977 Dec; 4(2): 161-74. A detailed review of the test was presented in 1454405, Tjolsen A, Berge OG, Hunskaar S, Rosland JH, Hole K, 'The formalin test: an evaluation of the method', Pain, 1992 Oct; 51(1): 5-17.

Vestibular function
Tests of the mice's vestibular function (balance). The most common test is contact righting, in which the mice are placed on their backs in a tight tube with a square cross-section and scored on their ability to turn themselves the right way up. Good descriptions of the test can be found in 3696494, Pellis SM, Pellis VC, Teitelbaum P, ''Axial apraxia' in labyrinthectomized lateral hypothalamic-damaged rats', Neurosci Lett, 1987 Nov 23; 82(2): 217-20, and 15283975, Khan Z, Carey J, Park HJ, Lehar M, Lasker D, Jinnah HA, 'Abnormal motor behavior and vestibular dysfunction in the stargazer mouse mutant', Neuroscience, 2004; 127(3): 785-96.

Motor Control Tests

A good general reference for motor control tests is 9789738, 'Shukitt-Hale B, Mouzakis G, Joseph JA, 'Psychomotor and spatial memory performance in aging male Fischer 344 rats', Exp Geron 1998; 33: pp. 615-624.

Rotarod (non-learning)
The rotarod is a test of motor coordination. The mouse is placed on a horizontal rod, the height of the rod above a surface is such that it forms an incentive for the mouse to remain on it and not fall to the floor. The rod rotates, obliging the mouse to keep moving in order to stay on it. The length of time the mouse manages to stay on the rod before falling is taken as a measure of motor coordination. A modification is that the rod may gradually accelerate until even the most competent mice are unable to remain.
A key early reference is 13502156, Dunham NW, Miya TS, 'A note on a simple apparatus for detecting neurological deficit in rats and mice', J Am Pharm Assoc Am Pharm Assoc (Baltim), 1957 Mar; 46(3): 208-9 (also available through ScienceDirect) A more recent description of the test can be found in 7478307, Lalonde R, Bensoula AN, Filali M, 'Rotorod sensorimotor learning in cerebellar mutant mice', Neurosci Res, 1995 Jul; 22(4): 423-6.

Grip strength: wire hang test
The mouse is made to hang by its front paws from a horizontal wire (the prehensile reflex). The length of time it manages to hold on for is taken as a measure of grip strength.
The test is described in 8451272, Lalonde R, Joyal CC, Botez MI, 'Effects of folic acid and folinic acid on cognitive and motor behaviors in 20-month-old rats', Pharmacol Biochem Behav, 1993 Mar; 44(3): 703-7.

Grip strength: loaded grid
On a similar principle to the wire hang test, the mouse is placed on a grid (perhaps of wire mesh), to which it can hold on with its paws. It is then gently pulled backwards by the tail. A device such as an isometric transducer is attached to the grid, allowing the force being applied to be controlled and measured. The lowest force at which the mouse loses its grip is taken as a measure of grip strength.
The test was first described in 551317, Meyer OA, Tilson HA, Byrd WC, Riley MT, 'A method for the routine assessment of fore- and hindlimb grip strength of rats and mice', Neurobehav Toxicol, 1979 Fall; 1(3): 233-6.
A good description of a similar test, in which the grid is replaced with a ring to which the mouse clings, can be found in 16860407, Lalonde R, Kim HD, Fukuchi K, 'Exploratory activity, anxiety and motor coordination in bigenic APPswe + PS1/DeltaE9 mice', Neurosci Lett, 2004 Oct 14; 369(2): 156-61.

Locomotor activity
The mouse is placed in a large open field; typically a flat surface surrounded by high, vertical walls. The amount of locomotor activity is then recorded. This is typically done using infra-red beam recording technology. This entails setting up a grid of infra-red beams at regular intervals around the arena; the experimenter then counts the number of beam breaks made by the animal. A second grid, higher from the floor, can also be used to detect rearing, which is accentuated, for example, in some drug-states.
NB: this test is not to be confused with the Open field test, although in apparatus and procedure they are superficially similar. The open field measures different parameters of the mouse's behaviour, and is specifically used as a measure of exploratory behaviour and anxiety.

Walking tests
Tests of mice's ability to walk include bar-crossing and beam balance.

The bar-crossing test involves placing the mouse at one end of a horizontal bar or plank. The distance it travels along the bar, and the number of turns executed, are taken as measures of its walking abilities and motor coordination. A detailed description can be found in 15561463, de Caprona MD, Beisel KW, Nichols DH, Fritzsch B, 'Partial behavioral compensation is revealed in balance tasked mutant mice lacking otoconia', Brain Res Bull, 2004 Dec 15; 64(4): 289-301.
In the beam balance test, the mouse is placed on a horizontal beam above the table surface, and its latency to fall off is recorded. The test is well described in 14637233, Lalonde R, Hayzoun K, Selimi F, Mariani J, Strazielle C, 'Motor coordination in mice with hotfoot, Lurcher, and double mutations of the Grid2 gene encoding the delta-2 excitatory amino acid receptor', Physiol Behav, 2003 Nov; 80(2-3): 333-9.

Vertical pole test
The vertical pole test is used to investigate the motor balance ability of mice. The mouse is placed onto a vertical pole (the pole may start out horizontal but then be gently elevated to the vertical). The experimenter either records the length of time before the mouse falls off the pole, or whether the mouse manages to descend the pole and how long it takes to do so.
A good description of the test can be found in 16753976, Abramow-Newerly W, Lipina T, Abramow-Newerly M, Kim D, Bechard AR, Xie G, Clapcote SJ, Roder JC, 'Methods to rapidly and accurately screen a large number of ENU mutagenized mice for abnormal motor phenotypes', Amyotroph Lateral Scler, 2006 Jun; 7(2): 112-8.

Locomotor sensitisation to a Drug or Hormone
Various drugs and hormones are known to produce sensitisation in rodents, i.e. over repeated exposures to the drug, the mice show an increased locomotor response to it. This is observed, for example, with cocaine. It is often informative to investigate whether this sensitisation also occurs in knockout mice. A key early reference on locomotor sensitisation procedures is Kendall JW, 'Dexamethasone stimulation of running activity in the male rat', Hormone Behav, 1970, 1: 327-336 (no PubMed ID). A detailed description of the test can be found in 1606506, Segal DS, Kuczenski R, 'Repeated cocaine administration induces behavioral sensitization and corresponding decreased extracellular dopamine responses in caudate and accumbens', Brain Res, 1992 Apr 17; 577(2): 351-5.

Swimming
Swimming is less frequently used as a measure of motor ability, due to the increased stress it places on the mice and the consequent confounds with anxiety-related changes in behaviour. Typical measures are the distance travelled and the speed achieved.
Detailed procedures for analysing swimming ability are described in 8919091, Bolivar VJ, Manley K, Fentress JC, 'The development of swimming behavior in the neurological mutant weaver mouse', Dev Psychobiol, 1996 Mar; 29(2): 123-37 (available on Wiley InterScience).

Gait analysis
Gait analysis is the process of analysing the mouse's walking process in detail, recording for example the length of its stride. Key reference describing optimal methods of gait analysis are 10405098, Clarke KA, Still J, 'Gait analysis in the mouse', Physiol Behav, 1999 Jul; 66(5): 723-9, and 11772434, Fernagut PO, Diguet E, Labattu B, Tison F, 'A simple method to measure stride length as an index of nigrostriatal dysfunction in mice', J Neurosci Methods, 2002 Jan 30; 113(2): 123-30.

Emotional State/Anxiety Tests

A good review of anxiety tests can be found in 2858080, Crawley JN, 'Exploratory behavior models of anxiety in mice', Neurosci Biobehav Rev, 1985 Spring; 9(1): 37-44.

Elevated plus maze
The elevated plus maze is a commonly-used test of anxiety. It uses a plus- or cross-shaped maze, elevated some distance above the ground. Two of the arms are enclosed while two are open. When first exposed to this novel environment, mice experience an approach/avoidance conflict: they wish to explore but are also anxious and thus inclined to retreat. The enclosed arms are less fearful than the open arms. Consequently, anxious rodents would be expected to spend more time in the enclosed arms than in the open ones.
The test was first described in 2864480, 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 Aug; 14(3): 149-67. A good review of the test's use can be found in 3110839, Lister RG, 'The use of a plus-maze to measure anxiety in the mouse', Psychopharmacology (Berl), 1987; 92(2):180-5 (also available through SpringerLink).

Open field
The open field test can use essentially the same apparatus as the Locomotor activity test described previously, but more parameters are measured.
The mouse is placed in an open arena and allowed to explore freely. Mice will generally stay close to the outer walls of the arena, as they have a strong avoidance reaction towards open spaces; they typically show a latency to approach the centre of the arena. Anxious mice will show exhibit a stronger form of this behaviour: they may take longer to approach the centre, and in some cases will not leave the walls at all. In most modern laboratories, the time at centre and time at walls is measured with automated digital video-tracking systems.
The test was first described in Hall CS, 'Emotional behavior in the rat. I. Defecation and urination as measures of individual differences in emotionality', Journal of Comparative Psychology, 1934 Dec, 18(3) 385-403.

Light/dark box
In this test, the mice are placed in a two-chambered arena, one chamber being illuminated and the other dark. Mice are free to move between the two areas, and more anxious mice will generally remain in the dark chamber, making relatively few forays into the light chamber.
The test was first described in 6106204, Crawley J, Goodwin FK, 'Preliminary report of a simple animal behavior model for the anxiolytic effects of benzodiazepines', Pharmacol Biochem Behav, 1980 Aug; 13(2): 167-70.

Emergence neophobia

Mirror box
Here the mouse is placed in a large box, which contains a smaller, mirrored box. The mouse's latency to enter the mirror box is recorded. Anxious mice will generally be more reluctant to enter the mirror box.
The test was first described in 2315349, Toubas PL, Abla KA, Cao W, Logan LG, Seale TW, 'Latency to enter a mirrored chamber: a novel behavioral assay for anxiolytic agents', Pharmacol Biochem Behav, 1990 Jan; 35(1): 121-6.

Hole board
Here the mouse is placed on a flat board that has a number of holes in it, opening into small pits. Anxious mice will tend to avoid these holes, and will consequently show a reduced number of head-dipping movements to them.
The test was first described in Boissier JR, Simon P, 'Dissociation de deux composantes dans le comportement d'investigation de la souris', Arch Int Pharmacodyn, 1964; 147: 372-387 (not available online). Good references are 5389125, Valzelli L, 'The exploratory behaviour in normal and aggressive mice', Psychopharmacologia, 1969; 15(3): 232-5, and 1197579, File SE, Wardill AG, 'The reliability of the hole-board apparatus', Psychopharmacologia, 1975 Oct 14; 44(1): 47-51 (available through SpringerLink).

Porsolt forced-swim test
The Porsolt forced-swim test is a measure of 'behavioural despair'. It is considered to be an animal model of learned helplessness, a symptom also observed in human depression. The mouse is placed in a small, liquid-filled container from which escape is impossible. Consequently, after a period of activity the mouse lapses into immobility and floats. Mice that take longer to float can be regarded as 'less prone to depression'. As latency to float increases in mice that are treated with anti-depressants, it is widely used as a screening model for antidepressants in the pharmaceutical industry.
The test was first described in 596982, Porsolt RD, Bertin A, Jalfre M, 'Behavioral despair in mice: a primary screening test for antidepressants', Arch Int Pharmacodyn Ther, 1977 Oct; 229(2): 327-36. The phenomenon of learned helplessness was first described in rodents in 1150936, Seligman ME, Rosellini RA, Kozak MJ, 'Learned helplessness in the rat: time course, immunization, and reversibility', J Comp Physiol Psychol, 1975 Feb; 88(2): 542-7.

Tail suspension test
Similarly to the Porsolt forced-swim test, the tail suspension test is a measure of 'behavioural despair'. The mouse is suspended above a surface by its tail for a fixed period of time. It is impossible for the mouse to escape this situation. The amount of time the mouse spends immobile is recorded, either through an automated system, or by an observer with a stopwatch.
The test was first described in 3923523, Steru L, Chermat R, Thierry B, Simon P, 'The tail suspension test: a new method for screening antidepressants in mice', Psychopharmacology (Berl), 1985; 85(3): 367-70. A good recent reference is 11297714, Liu X, Gershenfeld HK, 'Genetic differences in the tail-suspension test and its relationship to imipramine response among 11 inbred strains of mice', Biol Psychiatry, 2001 Apr 1; 49(7): 575-81.

Resident intruder
The resident intruder test is used as a measure of territorial aggression. A 'resident' mouse is housed alone in a cage for 24 hours, after which time a naive 'intruder' mouse is placed in the cage. The vast majority of resident mice will defend their territory from the intruder, by attacking it. Changes in the latency to attack, the resident's success rate and the level of wounding inflicted are all taken to be measures of aggression. More modern labs place the intruder into a separate cage within the resident's environment, so contacts can be observed but unnecessary harm to the intruder mouse is limited.
The test was first described in 1237905, Thurmond JB, 'Technique for producing and measuring territorial aggression using laboratory mice', Physiol Behav, 1975 Jun; 14(6): 879-81.

Social / Sexual Behaviour
Mice normally perform a wide variety of social, sexual and parental behaviours. For example, males will sometimes engage in post-oestrous coitus. Mice will also build nests using the bedding in their cages. Mothers will retrieve their pups to the nest. Changes in any of these types of behaviour are recorded here.

Cerebellar Tests

Eyeblink conditioning
Eyeblink conditioning is a form of classical (Pavlovian) conditioning in which an animal learns to associate a neutral stimulus (such as a tone) with an aversive stimulus, (a puff of air to the eye). The presentation of the aversive stimulus will cause a behaviour (physiological response) to be elicited (eye-blink). Eventually, presentation of the neutral stimulus (tone) alone will cause the animal to blink. Learning is said to have occurred when the animal blinks in response to the tone.
Evidence for cerebellar involvement is presented in 8786457, Chen L, Bao S, Lockard JM, Kim JK, Thompson RF, 'Impaired classical eyeblink conditioning in cerebellar-lesioned and Purkinje cell degeneration (pcd) mutant mice', J Neurosci. 1996 Apr 15; 16(8):2829-38.

Rotarod learning
Rotarod learning is an extension of the Rotarod procedure used to assess motor coordination.
As in the standard rotarod test, the mouse is placed on a rotating horizontal bar and the latency to fall off is recorded. However, if the procedure is repeated several times, one can determine how much the mouse improves with successive trials. It is therefore a test of learning as well as of motor coordination.
Evidence for a cerebellar involvement in this task can be found in 8833100, Lalonde R, Filali M, Bensoula AN, Lestienne F, 'Sensorimotor learning in three cerebellar mutant mice', Neurobiol Learn Mem, 1996 Mar; 65(2): 113-20, and in 16860407, Goddyn H, Leo S, Meert T, D'Hooge R, 'Differences in behavioural test battery performance between mice with hippocampal and cerebellar lesions', Behav Brain Res, 2006 Oct 2; 173(1): 138-47.

Pre-pulse inhibition
PPI is a form of sensory gating, in which a preceding sub-threshold stimulus reduces an animal's startle response to a loud tone (acoustic startle, itself used as a measure of hearing). Mice are placed in to a small chamber, which is fitted with a motion detection system. They then hear a number of sounds, at different volumes. On some trials, a brief, quieter sound is played immediately before the louder sound. The animals learn that the quick, soft tone is a signal for a loud noise, allowing them to prepare for the loud noise and thus to show a reduced startle response.
PPI was first described in 7375610, Hoffman HS, Ison JR, 'Reflex modification in the domain of startle: I. Some empirical findings and their implications for how the nervous system processes sensory input', Psychol Rev, 1980 Mar; 87(2): 175-89.
A good review of the literature on PPI can be found in 8297213, Swerdlow NR, Braff DL, Taaid N, Geyer MA, 'Assessing the validity of an animal model of deficient sensorimotor gating in schizophrenic patients', Arch Gen Psychiatry, 1994 Feb; 51(2): 139-54.

Amygdalar Learning Tests

Fear-potentiated startle
Fear-potentiated startle is another form of conditioning. The mice are exposed to two different conditioned stimuli, typically an auditory tone and a visual stimulus such as a light. For each mouse, one of these stimuli will be associated with an aversive stimulus such as an electric shock.
Following training, the mice are subjected to startle-inducing stimuli, generally loud tones. Some of these stimuli are preceded by one of the two conditioned stimuli. The stimulus that was previously associated with the electric shock triggers a fear reaction, enhancing the startle reaction to the subsequent loud tone. By contrast, the stimulus that was not associated with an electric shock does not potentiate the startle response in this way. The startle response is thus potentiated by one conditioned stimulus but not the other.
For evidence that this test is amygdala-dependent, see 10959534, Heldt S, Sundin V, Willott JF, Falls WA, 'Posttraining lesions of the amygdala interfere with fear-potentiated startle to both visual and auditory conditioned stimuli in C57BL/6J mice', Behav Neurosci, 2000 Aug; 114(4): 749-59, 3954873, Hitchcock J, Davis M, 'Lesions of the amygdala, but not of the cerebellum or red nucleus, block conditioned fear as measured with the potentiated startle paradigm', Behav Neurosci, 1986 Feb; 100(1):11-22, and 7891168, Campeau S, Davis M, 'Involvement of the central nucleus and basolateral complex of the amygdala in fear conditioning measured with fear-potentiated startle in rats trained concurrently with auditory and visual conditioned stimuli', J Neurosci, 1995 Mar; 15(3 Pt 2): 2301-11.

Conditioned emotional response
Conditioned emotional response (CER) is a form of conditioned learning. Mice are placed in an operant chamber and taught a simple operant task, typically to press a lever to obtain food rewards. Once they have achieved a stable response rate, the operant trials are interspersed with a second trial type in which an auditory tone is presented, followed by a footshock. The footshock produces a decrease in the lever-pressing behaviour. After a few such trials, the tone alone will also produce a drop in lever-pressing. The response is deemed to be emotional, as it causes a conflict in the mouse, which is hungry and wants the food, but does not want the shock.
Key evidence that CER is amygdala-dependent can be found in 11184794, Molino A, 'Sparing of function after infant lesions of selected limbic structures in the rat', J Comp Physiol Psychol, 1975 Oct; 89(8): 868-81, and in 12458789, Jain S, Mathur R, Sharma R, Nayar U, 'Recovery from lesion-associated learning deficits by fetal amygdala transplants', Neural Plast, 2002; 9(1): 53-63.

Cued / delayed fear conditioning
Cued (also known as 'delayed') fear conditioning is one of the basic forms of fear conditioning. A conditioned stimulus (CS), such as an auditory tone, is paired with an unconditioned aversive stimulus (US), generally an electric footshock. The defining feature of cued conditioning is that the CS is first presented, then there is a short delay, and then the US is presented. This differs from trace fear conditioning, in which the US occurs immediately as the CS concludes. Normal mice will readily form an association between the CS and US. This is tested by presenting the CS on its own and recording fearful behaviours such as freezing; such testing must be conducted in a new chamber to avoid any confounding effects from contextual learning.
A paper showing the neural dissociation between cued and contextual fear conditioning is 1590953, Phillips RG, LeDoux JE, 'Differential contribution of amygdala and hippocampus to cued and contextual fear conditioning', Behav Neurosci, 1992 Apr; 106(2): 274-85.

Radial arm maze: conditioned cue preference
The radial arm maze consists of a central area with eight arms radiating out from it. It can be adapted to a wide range of behavioural tests.
In this task, each arm of the maze is signified by a different visual marker, such as a pattern on floor or lining of the tube. Four of the arms, consistently the same four for each mouse, are baited with food pellets. Over successive trials, the mice have to learn which arms (which patterns) are baited. The order and positions of the arms is varied randomly. The task is non-hippocampal and is primarily about learning a visual discrimination.
The task was shown to be amygdala-dependent in 8447956, McDonald RJ, White NM, 'A triple dissociation of memory systems: hippocampus, amygdala, and dorsal striatum', Behav Neurosci, 1993 Feb; 107(1): 3-22. The authors showed a dissociation between the conditioned cue preference task (impaired by amygdala lesions), the win-shift task (impaired by hippocampal lesions) and the win-stay task (impaired by striatal lesions).

Step-through/down passive avoidance
In passive avoidance, mice are placed in a shuttlebox with two connected chambers. One of the chambers is fitted with a footshock apparatus. The mouse is initially placed in the safe chamber. As soon as it crosses into the other chamber, it receives a footshock. The mouse's task is to learn to stay in the first chamber and not to explore the other chamber. It is therefore a passive avoidance mechanism, as the mouse learns not to take a particular action. This is in contrast to active avoidance.
For evidence that passive avoidance is amygdala-dependent, see 996162, Nagel JA, Kemble ED, 'Effects of amygdaloid lesions on the performance of rats in four passive avoidance tasks', Physiol Behav, 1976 Aug; 17(2):245-50, and 4001190, Jellestad FK, Bakke HK, 'Passive avoidance after ibotenic acid and radio frequency lesions in the rat amygdala', Physiol Behav, 1985 Feb; 34(2): 299-305.

Hippocampal Learning Tests

Trace fear conditioning
Trace fear conditioning is one of the basic forms of fear conditioning. A conditioned stimulus (CS), such as an auditory tone, is paired with an unconditioned aversive stimulus (US), generally an electric footshock. The defining feature of trace conditioning is that the CS is first presented, and then the US is presented either while the CS is still continuing (in which case they usually co-terminate) or immediately as it finishes. This differs from cued fear conditioning, in which the US occurs some time after the CS has concluded. Normal mice will readily form an association between the CS and US. This is tested by presenting the CS on its own and recording fearful behaviours such as freezing; such testing must be conducted in a new chamber to avoid any confounding effects from contextual learning.
For a sample of the evidence of hippocampal requirement for trace fear conditioning, see 16504548, Rogers JL, Hunsaker MR, Kesner RP, 'Effects of ventral and dorsal CA1 subregional lesions on trace fear conditioning', Neurobiol Learn Mem, 2006 Jul; 86(1): 72-81 and 15669102, Misane I, Tovote P, Meyer M, Spiess J, Ogren SO, Stiedl O, 'Time-dependent involvement of the dorsal hippocampus in trace fear conditioning in mice', Hippocampus, 2005; 15(4): 418-26.

Contextual fear conditioning
The procedure for contextual fear conditioning is the same as is used for cued and trace fear conditioning, and indeed the training sessions for the two can be shared, with only a distinct testing session required to assess the mouse's learning.
When a mouse goes through a fear conditioning training trial, as well as acquiring the association between the tone and the footshock, it will also learn to associate the footshock with the environment it is in, typically a shuttlebox. This can be assessed by returning the mouse to the training chamber but presenting no stimuli, i.e. neither the tone nor the footshock. Normal mice will nevertheless show increased freezing behaviour when placed back in the chamber.
A classic paper showing the neural dissociation between cued and contextual fear conditioning is 1590953, Phillips RG, LeDoux JE, 'Differential contribution of amygdala and hippocampus to cued and contextual fear conditioning', Behav Neurosci, 1992 Apr; 106(2): 274-85.

Water maze acquisition
The water maze, originally developed by Morris, has become one of the most widely-used procedures in behavioural science. A great many variations on the task have also been developed. See also the visible platform version, which is normally performed as a control.
The water maze consists of a circular tank, the dimensions of which vary considerably between different labs. It is filled with water, made opaque with some form of white powder. Somewhere in the maze, in a consistent location throughout training, is a platform that is just under the surface of the water, and consequently invisible. A mouse placed in the maze will typically swim around randomly until by chance it locates the platform. Because mice have a strong aversion to water, finding the platform serves as a strong reward. On subsequent trials, they must learn the location of the platform and to navigate to it, using conspicuous distal cues spaced around the room. Their behaviour can be assessed on a number of variables, such as time taken to find the platform and distance travelled to the platform. Modern labs generally use automated tracking systems to obtain a complete record of the mouse's movements.
The water maze was first described in Morris RGM, 'Spatial localisation does not depend on the presence of local cues', Learning Motivation, 1981; 12: 239-260. An early description can be found in 6471907, Morris R, 'Developments of a water-maze procedure for studying spatial learning in the rat', J Neurosci Methods, 1984 May; 11(1): 47-60.
The literature on the water maze is very extensive. Two key early papers indicating that it is hippocampus-dependent are 6830648, Sutherland RJ, Whishaw IQ, Kolb B, 'A behavioural analysis of spatial localization following electrolytic, kainate- or colchicine-induced damage to the hippocampal formation in the rat', Behav Brain Res, 1983 Feb; 7(2): 133-53 and 7088155, Morris RG, Garrud P, Rawlins JN, O'Keefe J, 'Place navigation impaired in rats with hippocampal lesions', Nature, 1982 Jun 24; 297(5868): 681-3.

Water maze probe
The water maze, originally developed by Morris, has become one of the most widely-used procedures in behavioural science. A great many variations on the task have also been developed. See also the visible platform version, which is normally performed as a control.
The probe trial is a standard method of assessing whether learning has occurred during training. In the water maze probe, the hidden platform is removed and the mouse is once again placed in the tank. If it has learned the platform's location, it should spend the majority of its time in the platform's last known location, or at least in the same quadrant of the tank. This is indeed observed in normal mice, and thus provides a sensitive assay for learning in mutant mice.
The literature on the water maze is very extensive. Two key early papers indicating that it is hippocampus-dependent are 6830648, Sutherland RJ, Whishaw IQ, Kolb B, 'A behavioural analysis of spatial localization following electrolytic, kainate- or colchicine-induced damage to the hippocampal formation in the rat', Behav Brain Res, 1983 Feb; 7(2): 133-53 and 7088155, Morris RG, Garrud P, Rawlins JN, O'Keefe J, 'Place navigation impaired in rats with hippocampal lesions', Nature, 1982 Jun 24; 297(5868): 681-3.

Water maze reversal
Reversal learning is an additional test of the mouse's ability to learn, once the initial acquisition trials (and generally a probe) have been performed. The location of the hidden platform is moved to the opposite end of the tank. The mouse is assessed on how rapidly it manages to learn the new location.
Performance in reversal learning trials seems to depend on more systems than the standard acquisition trials.

For evidence of hippocampal involvement, see 8515847, Netto CA, Hodges H, Sinden JD, Le Peillet E, Kershaw T, Sowinski P, Meldrum BS, Gray JA, 'Effects of fetal hippocampal field grafts on ischaemic-induced deficits in spatial navigation in the water maze', Neuroscience, 1993 May; 54(1): 69-92.
Reversal training, as well as testing the animal's learning ability, is also a measure of behavioural flexibility. This is thought to involve the prefrontal cortex: for instance, see 7953746, de Bruin JP, Sanchez-Santed F, Heinsbroek RP, Donker A, Postmes P, 'A behavioural analysis of rats with damage to the medial prefrontal cortex using the Morris water maze: evidence for behavioural flexibility, but not for impaired spatial navigation', Brain Res, 1994 Aug 1; 652(2): 323-33.
There is also evidence for involvement of other regions: for example, see 2354359, Mundy WR, Barone S, Tilson HA, 'Neurotoxic lesions of the nucleus basalis induced by colchicine: effects on spatial navigation in the water maze', Brain Res, 1990 Apr 2; 512(2): 221-8.

Plus-shaped water maze (cues in room)
The plus-shaped water maze is a delayed-match-to-sample test using an apparatus similar to the conventional circular water maze. The apparatus is again a water tank, the water having been made opaque by the addition of a white powder. However, the tank is now plus-shaped, with four identical arms radiating at right angles off a central square. At the end of one of the arms, a platform is hidden just under the surface of the water; it provides a means by which the mouse can escape the water, but is invisible. The platform is consistently placed at the end of the same arm, in the same spatial location in the room, on each trial. The mouse is placed in the pool in one of the arms that does not contain the platform. Its task is to learn which arm consistently contains the platform, and to swim directly to it.
A good early reference describing the plus-shaped water maze is 2702490, Decker MW, McGaugh JL, 'Effects of concurrent manipulations of cholinergic and noradrenergic function on learning and retention in mice', Brain Res, 1989 Jan 16; 477(1-2): 29-37.
Evidence that delayed-match-to-sample in the water maze (though not using a plus-shaped maze) is hippocampus-dependent is given in 10226773, Steele RJ, Morris RG, 'Delay-dependent impairment of a matching-to-place task with chronic and intrahippocampal infusion of the NMDA-antagonist D-AP5', Hippocampus, 1999; 9(2): 118-36.

Barnes maze
The Barnes maze is a circular surface, with a large number (normally 20) of holes around the circumference. One of these holes leads to a 'drop box', which provides shelter underneath the surface. The surface of the maze is brightly lit, and other aversive stimuli such as loud buzzing noises are also present. This negative reinforcement encourages the mouse to seek shelter, which the drop box provides. Normal mice learn to go directly to the drop box after only a small number of trials.
The Barnes maze was first described in 221551, Barnes CA, 'Memory deficits associated with senescence: a neurophysiological and behavioral study in the rat', J Comp Physiol Psychol, 1979 Feb; 93(1): 74-104.
There is evidence for hippocampal involvement in 2792242, McNaughton BL, Barnes CA, Meltzer J, Sutherland RJ, 'Hippocampal granule cells are necessary for normal spatial learning but not for spatially-selective pyramidal cell discharge', Exp Brain Res, 1989; 76(3): 485-96.

T-maze: spatial
T-mazes can be used for a wide variety of behavioural tests, probing a range of different cognitive faculties.

In the spatial version, each trial consists of an information run followed by a choice run. In the information run, the mouse is placed in the stem of the T and walks to the choice point. However, one of the arms has been blocked off so the mouse is forced to enter the other one, where it finds a food reward and is allowed to eat it. It is then returned to the start point. For the second, choice, run the blockage is removed, so the mouse has the choice of which arm to enter. However, only the arm that it was not previously allowed to enter contains a food reward. The mouse's task is therefore to enter the arm that it did not visit on the information run. The task taps working memory as well as spatial memory.
The literature on T-mazes is extensive. Evidence that spatial learning in T-mazes is hippocampal can be found in 6785882, Thompson R, 'Rapid forgetting of a spatial habit in rats with hippocampal lesions', Science, 1981 May 22; 212(4497): 959-60, and 7126316, Rawlins JN, Olton DS, 'The septo-hippocampal system and cognitive mapping', Behav Brain Res, 1982 Aug; 5(4): 331-58.

T-maze: spontaneous alternation (non-rewarded)
Spontaneous alternation is a naturally-occurring behaviour in mice that are repeatedly placed in a T-maze. The mouse is placed in the stem of the T and allowed to explore freely until it enters one of the arms. It is then returned to the start point. Normal mice will enter the arm that they have not previously entered - the task therefore provides a sensitive test for hippocampal functioning. Note that at no point in the task does the mouse receive any reward.
Spontaneous alternation was first described in 5969595, Douglas RJ, 'Cues for spontaneous alternation', J Comp Physiol Psychol, 1966, 62: 171-183.
Evidence for involvement of the hippocampal system is given in 2765174, Pacteau C, Einon D, Sinden J, 'Early rearing environment and dorsal hippocampal ibotenic acid lesions: long-term influences on spatial learning and alternation in the rat', Behav Brain Res, 1989 Aug 1;34(1-2): 79-96 and 3675832, Gibbs RB, Yu J, Cotman CW, 'Entorhinal transplants and spatial memory abilities in rats', Behav Brain Res, 1987 Oct; 26(1): 29-35.

Y-maze: spatial
Y-mazes can be used for two-way active avoidance tasks; such tests are classed as 'Two-way active avoidance', below.
Many Y-maze tasks are hippocampal: see for example 2590146, Sutherland RJ, McDonald RJ, Hill CR, Rudy JW, 'Damage to the hippocampal formation in rats selectively impairs the ability to learn cue relationships', Behav Neural Biol, 1989 Nov; 52(3): 331-56, 8986335, Conrad CD, Galea LA, Kuroda Y, McEwen BS, 'Chronic stress impairs rat spatial memory on the Y maze, and this effect is blocked by tianeptine pretreatment', Behav Neurosci, 1996 Dec; 110(6): 1321-34, and 8397861, Kelsey JE, Vargas H, 'Medial septal lesions disrupt spatial, but not nonspatial, working memory in rats', Behav Neurosci, 1993 Aug; 107(4): 565-74.

Y-maze: non-spatial

Y-maze: spontaneous alternation

Reactivity to spatial change
In this test, the mouse is first placed in an area containing two novel objects. It is allowed to explore them freely and to habituate to them. It is then removed from the arena for a period that varies. Following this delay, it is returned to the arena. The same two objects are still present, but one of them has been moved to a new spatial location within the arena. Normal rats will preferentially explore the object that has been moved, as it is novel.
This test was first described in 9108217, Ennaceur A, Neave N, Aggleton JP, 'Spontaneous object recognition and object location memory in rats: The effects of lesions in the cingulate cortices, the medial prefrontal cortex, the cingulum bundle and the fornix', Exp Brain Res, 1997; 113: 509-519.
A recent paper showing that the test is hippocampus-dependent (and that object recognition is not) is 11992015, Mumby DG, Gaskin S, Glenn MJ, Schramek TE, Lehmann H, 'Hippocampal damage and exploratory preferences in rats: memory for objects, places, and contexts', Learn Mem, 2002 Mar-Apr; 9(2): 49-57.

Radial arm maze winshift
The radial arm maze consists of a central area with eight arms radiating out from it. It can be adapted to a wide range of behavioural tests.
The winshift task is a test of spatial working memory. Food pellets are placed in all 8 arms. The mouse is placed in the central arena and is allowed to freely explore. The mouse enters an arm, finds a food pellet and eats it. When it returns to the centre, doors lower to temporarily close off all the arms. After a delay, the doors are opened and the mouse is once again allowed to enter an arm - the whole process is then repeated. In order to obtain all the food, the mouse has to go to each arm in turn. The trial continues until the mouse finds all eight food pellets. The experimenter records every action the mouse takes and grades its behaviour. It loses marks if it returns to a previously-visited arm.
The earliest description of the radial arm maze is given in Olten DS, Samuelson RJ, 'Remembrance of places passed: Spatial memory in rats', Journal of Experimental Psychology: Animal Behavior Processes, 1976, 2, 97-116.
The neural underpinnings of the different radial arm maze tasks were dissociated in 8447956, McDonald RJ, White NM, 'A triple dissociation of memory systems: hippocampus, amygdala, and dorsal striatum', Behav Neurosci, 1993 Feb; 107(1):3-22. The authors showed a dissociation between the conditioned cue preference task (impaired by amygdala lesions), the win-shift task (impaired by hippocampal lesions) and the win-stay task (impaired by striatal lesions).

Visual radial arm maze
The radial arm maze consists of a central area with eight arms radiating out from it. It can be adapted to a wide range of behavioural tests.
The test was first described, and shown to be hippocampus-dependent, in 7215498, Olton DS, Feustle WA, 'Hippocampal function required for nonspatial working memory', Exp Brain Res, 1981; 41:380-389.

Striatal Learning Tests

Radial arm maze winstay
The radial arm maze consists of a central area with eight arms radiating out from it. It can be adapted to a wide range of behavioural tests.
The winstay task is run in a dark room. Four of the arms of the maze are baited with food pellets; these arms are also selectively illuminated. The mouse starts in the centre of the maze and is allowed to freely explore. Upon entering one of the lit arms, it will discover and eat the food pellet therein. It then returns to the centre, at which point entry to the arms is blocked by descending doors. The mouse stays blocked in the centre for about 10 seconds, during which time the food it has eaten is replenished. The doors are then opened and it is again allowed to freely explore. The 'correct' choice is to return to the first arm, where it will again discover food. Upon returning to the centre for the second time, the light in that arm is switched off. The procedure can then be repeated for the three remaining illuminated and baited arms.
The task was shown to be striatum-dependent in 8447956, McDonald RJ, White NM, 'A triple dissociation of memory systems: hippocampus, amygdala, and dorsal striatum', Behav Neurosci, 1993 Feb; 107(1): 3-22. The authors showed a dissociation between the conditioned cue preference task (impaired by amygdala lesions), the win-shift task (impaired by hippocampal lesions) and the win-stay task (impaired by striatal lesions).

Stimulus-response learning
This is a test of habit learning in which the animal learns to make a response only when a certain stimulus is present.
A typical set-up is to place the mouse in a box with a lever and a light. When the light is on, pressing the lever causes a food pellet to be deposited in the box with 100% reliability. However, when the light is not on, pressing the lever has no effect. The mouse must therefore learn to press the lever only when the light is on.

T-maze: non-spatial (left/right discrimination)
Evidence that 'brightness discrimination in a T-maze' is non-hippocampal is given in 7248806, Munoz C, Grossman SP, 'Spatial discrimination, reversal and active or passive avoidance learning in rats with KA-induced neuronal depletions in dorsal hippocampus', Brain Res Bull, 1981 May; 6(5): 399-406.

2-way active avoidance
1521605, Sengstock GJ, Johnson KB, Jantzen PT, Meyer EM, Dunn AJ, Arendash GW, 'Nucleus basalis lesions in neonate rats induce a selective cortical cholinergic hypofunction and cognitive deficits during adulthood', Exp Brain Res, 1992; 90(1): 163-74.

Tests requiring Multiple or Undetermined Brain Regions

Water maze visible platform
Evidence that the visible platform test is non-hippocampal (and indeed non-limbic) is presented in 1449643, McNamara RK, Kirkby RD, dePape GE, Corcoran ME, 'Limbic seizures, but not kindling, reversibly impair place learning in the Morris water maze', Behav Brain Res, 1992 Sep 28; 50(1-2): 167-75.

Lashley maze I
This is the simplest of the four Lashley mazes, and is rarely used.

Lashley maze II
This is the second simplest of the four Lashley mazes, and is rarely used.

Lashley maze III

This is a relatively complex maze; it contains cul-de-sacs that the mouse must to learn to avoid, as well as T-choices where the mouse has to learn to make the correct left or right turn. Sometimes the maze is filled with water. The picture below illustrates the layout of the maze.

Layout of a Lashley III
maze

The mice can learn the maze allocentrically, i.e. by using spatial cues, or egocentrically by memorizing the chain of correct left and right turns. Their performance can be measured in several ways, such as a 'learning index' (number of correct entries divided by total number of entries). Other useful measures are the number of cul-de-sac entries when swimming towards the goal, the number of incorrect left/right turns at choice points, and the number of backward errors (swimming away from the goal box).

Some evidence of hippocampal involvement is presented in 2288673, Dickson CT, Vanderwolf CH, 'Animal models of human amnesia and dementia: hippocampal and amygdala ablation compared with serotonergic and cholinergic blockade in the rat', Behav Brain Res, 1990 Dec 21; 41(3): 215-27.
However, a hippocampal lesion was shown not to impair performance on the maze in 12048174, Deacon RM, Bannerman DM, Kirby BP, Croucher A, Rawlins JN, 'Effects of cytotoxic hippocampal lesions in mice on a cognitive test battery', Behav Brain Res, 2002 Jun 15; 133(1): 57-68.
Further evidence, suggesting a role for the cortex, comes from 7552277, Rosen GD, Waters NS, Galaburda AM, Denenberg VH, 'Behavioral consequences of neonatal injury of the neocortex', Brain Res, 1995 May 29; 681(1-2): 177-89.
There is also evidence for a striatal component: 1521605, Sengstock GJ, Johnson KB, Jantzen PT, Meyer EM, Dunn AJ, Arendash GW, 'Nucleus basalis lesions in neonate rats induce a selective cortical cholinergic hypofunction and cognitive deficits during adulthood', Exp Brain Res, 1992; 90(1): 163-74.

Lashley maze IV
This is the most complex of the four Lashley mazes, and is rarely used.

PPI / sensorimotor gating (as learning test)

16644276, Frings M, Awad N, Jentzen W, Dimitrova A, Kolb FP, Diener HC, Timmann D, Maschke M, 'Involvement of the human cerebellum in short-term and long-term habituation of the acoustic startle response: a serial PET study', Clin Neurophysiol, 2006 Jun; 117(6): 1290-300 suggests that this is cerebellar (using PET scanning of humans).
14643083, Le Pen G, Kew J, Alberati D, Borroni E, Heitz MP, Moreau JL, 'Prepulse inhibition deficits of the startle reflex in neonatal ventral hippocampal-lesioned rats: reversal by glycine and a glycine transporter inhibitor', Biol Psychiatry, 2003 Dec 1; 54(11): 1162-70 suggests that PPI is hippocampal.
8554715, Kodsi MH, Swerdlow NR, ' Prepulse inhibition in the rat is regulated by ventral and caudodorsal striato-pallidal circuitry', Behav Neurosci, 1995 Oct; 109(5): 912-28 gives evidence for a striatal component.
There is also evidence for a role of the substantia nigra pars reticulata: 11099769, Koch M, Fendt M, Kretschmer BD, 'Role of the substantia nigra pars reticulata in sensorimotor gating, measured by prepulse inhibition of startle in rats', Behav Brain Res, 2000 Dec 20; 117(1-2): 153-62.

Water learning (finding)
This test was first described in 2569407, Ichihara K, Nabeshima T, Kameyama T, 'Differential effects of pimozile and SCH23390 on acquisition of learning in mice', Eur J Pharmacol, 1989; 164: 189 �195.
The neural underpinnings of the task are under-investigated, although there is one study suggesting that it is dependent on the dopaminergic system: 8093719, Ichihara K, Nabeshima T, Kameyama T, 'Dopaminergic agonists impair latent learning in mice: possible modulation by noradrenergic function', J Pharmacol Exp Ther, 1993 Jan; 264(1): 122-8.

Habituation to novel object exploration
Habituation to familiar objects, and a concurrent preference for exploration of a novel object, was first formalised as a memory test in 3228475, Ennaceur A, Delacour J, 'A new one-trial test for neurobiological studies of memory in rats. 1: Behavioral data', Behav Brain Res, 1988 Nov 1; 31(1): 47-59.
Evidence that the test is not hippocampus-dependent can be found in 11992015, Mumby DG, Gaskin S, Glenn MJ, Schramek TE, Lehmann H, 'Hippocampal damage and exploratory preferences in rats: memory for objects, places, and contexts', Learn Mem, 2002 Mar-Apr; 9(2): 49-57.

Social transmission of novel food preference
A recent paper addressing the methodology of this task is 12619904, Wrenn CC, Harris AP, Saavedra MC, Crawley JN, 'Social transmission of food preference in mice: methodology and application to galanin-overexpressing transgenic mice', Behav Neurosci, 2003 Feb; 117(1): 21-31.

Evidence for involvement of the hippocampus is presented in 8646281, Bunsey M, Eichenbaum H, 'Selective damage to the hippocampal region blocks long-term retention of a natural and nonspatial stimulus-stimulus association', Hippocampus, 1995; 5(6): 546-56, and in 12040072, Clark RE, Broadbent NJ, Zola SM, Squire LR, 'Anterograde amnesia and temporally graded retrograde amnesia for a nonspatial memory task after lesions of hippocampus and subiculum', J Neurosci, 2002 Jun 1; 22(11): 4663-9.
However, there is also evidence for involvement of the orbitofrontal cortex: 15897258, Ross RS, McGaughy J, Eichenbaum H, 'Acetylcholine in the orbitofrontal cortex is necessary for the acquisition of a socially transmitted food preference', Learn Mem, 2005 May-Jun; 12(3): 302-6.
A recent paper also implicates the nucleus basalis magnocellularis: 17101878, Boix-Trelis N, Vale-Martinez A, Guillazo-Blanch G, Costa-Miserachs D, Marti-Nicolovius M, 'Effects of nucleus basalis magnocellularis stimulation on a socially transmitted food preference and c-Fos expression', Learn Mem, 2006 Nov-Dec; 13(6): 783-93.
NMDA receptors may be particularly important, according to 12492304, Roberts M, Shapiro M, 'NMDA receptor antagonists impair memory for nonspatial, socially transmitted food preference', Behav Neurosci, 2002 Dec; 116(6): 1059-69.
Evidence for a role of the basal forebrain cholinergic neurons is given in 11153718, Berger-Sweeney J, Stearns NA, Frick KM, Beard B, Baxter MG, 'Cholinergic basal forebrain is critical for social transmission of food preferences', Hippocampus, 2000; 10(6): 729-38.
The task is not dependent on the mamillary bodies: see 15654859, Radyushkin K, Anokhin K, Meyer BI, Jiang Q, Alvarez-Bolado G, Gruss P, 'Genetic ablation of the mammillary bodies in the Foxb1 mutant mouse leads to selective deficit of spatial working memory', Eur J Neurosci, 2005 Jan; 21(1): 219-29.

Classical conditioning
Classical conditioning was first described by Ivan Pavlov, in one of the earliest studies of behavioural learning, conducted in the late 19th and early 20th centuries. His work first became widely available in English in 1927 with the publication of his book: Pavlov IP, 'Conditioned Reflexes: An Investigation of the Physiological Activity of the Cerebral Cortex' (translated by G. V. Anrep), 1927, London: Oxford University Press.

Evidence that Pavlovian conditioning is not dependent on the cortex (in the rabbit) is presented in 14677587, Oakley DA, Russell IS, 'Subcortical nature of Pavlovian differentiation in the rabbit', Physiol Behav, 1976 Dec; 17(6): 947-54.
Several subcortical regions, particularly the reticular formation, are implicated in 6322923, Irisawa N, Iwasaki T, 'Electrical activity of the reticular formation during aversive and appetitive conditioning in rats', Brain Res, 1984 Apr 2; 296(2): 211-23.
Evidence for a key role of the cerebellum is presented in 6883122, McCormick DA, Lavond DG, Thompson RF, 'Neuronal responses of the rabbit brainstem during performance of the classically conditioned nictitating membrane (NM)/eyelid response', Brain Res, 1983 Jul 18; 271(1): 73-88.
There is also a requirement for the medial geniculate region: see 3719322, Jarrell TW, Gentile CG, McCabe PM, Schneiderman N, 'The role of the medial geniculate region in differential Pavlovian conditioning of bradycardia in rabbits', Brain Res, 1986 May 21; 374(1): 126-36.
The hippocampus is also thought to be involved: see 6721923, Ross RT, Orr WB, Holland PC, Berger TW, 'Hippocampectomy disrupts acquisition and retention of learned conditional responding', Behav Neurosci, 1984 Apr; 98(2): 211-25.

Instrumental/operant conditioning
The earliest systematic study of instrumental conditioning was reported in Thorndike EL, 'Animal intelligence: An experimental study of the associative processes in animals', Psychological Review Monograph Supplement, 1901; 2: 1-109.

Evidence for involvement of the globus pallidus in conditioning was reported in 4997823, DeLong MR, 'Activity of pallidal neurons during movement', J Neurophysiol, 1971 May; 34(3): 414-27.
Lesions of the septum affect instrumental conditioning involving response suppression, according to 1194456, Ross JF, Grossman SP, 'Septal influences on operant responding in the rat', J Comp Physiol Psychol, 1975 Aug; 89(6): 523-36.
Depletion of the noradrenaline systems altered operant learning in 300082, Mason ST, Iversen SD, 'Effects of selective forebrain noradrenaline loss on behavioral inhibition in the rat', J Comp Physiol Psychol, 1977 Feb; 91(1): 165-73 and in 7082464, Owen S, Boarder MR, Gray JA, Fillenz M, 'Acquisition and extinction of continuously and partially reinforced running in rats with lesions of the dorsal noradrenergic bundle', Behav Brain Res, 1982 May; 5(1): 11-41.
Hippocampal lesions also affect instrumental learning, although their effects do not seem to specifically affect the process of learning: see 4039965, Shull RN, Holloway FA, 'Behavioral effects of hippocampal system lesions on rats in an operant paradigm', Brain Res Bull, 1985 Apr; 14(4): 315-22.
The neocortex does not appear to be required: see 7248065, Oakley DA, 'Performance of decorticated rats in a two-choice visual discrimination apparatus', Behav Brain Res, 1981 Jul; 3(1): 55-69.
Similarly, lesions of the nucleus accumbens impair performance in instrumental learning tasks, but this seems to reflect changes in affective arousal: 7718151, Balleine B, Killcross S, 'Effects of ibotenic acid lesions of the nucleus accumbens on instrumental action', Behav Brain Res, 1994 Dec 15; 65(2): 181-93.
A key review article is 9704982, Balleine BW, Dickinson A, 'Goal-directed instrumental action: contingency and incentive learning and their cortical substrates', Neuropharmacology, 1998 Apr-May; 37(4-5): 407-19.

Conditioned taste aversion

Evidence for some level of hippocampal involvement (though of indeterminate nature) was presented in 950393, Krane RV, Sinnamon HM, Thomas GJ, 'Conditioned taste aversions and neophobia in rats with hippocampal lesions', J Comp Physiol Psychol, 1976 Jul; 90(7): 680-93.
There is also evidence for some involvement of the amygdala: see 751424, Buresova O, 'Neocortico-amygdalar interaction in the conditioned taste aversion in rats', Act Nerv Super (Praha), 1978 Oct; 20(3): 224-30.
Similarly, the area postrema is also known to be involved: 3878977, Ossenkopp KP, Giugno L, Sutherland C, 'Conditioned taste aversions induced by 1-5-hydroxytryptophan are mediated by the area postrema', Prog Neuropsychopharmacol Biol Psychiatry, 1985; 9(5-6): 745-8.
The thalamus is also critical: see 3040033, Lasiter PS, 'Thalamocortical relations in taste aversion learning: II. Involvement of the medial ventrobasal thalamic complex in taste aversion learning', Behav Neurosci, 1985 Jun; 99(3): 477-95.
A study evaluating the effects of many different lesion sites was presented in 7792081, Yamamoto T, Fujimoto Y, Shimura T, Sakai N, 'Conditioned taste aversion in rats with excitotoxic brain lesions', Neurosci Res, 1995 Mar; 22(1): 31-49.
There is also evidence for involvement of the insular (gustatory) cortex: 9685579, Schafe GE, Bernstein IL, 'Forebrain contribution to the induction of a brainstem correlate of conditioned taste aversion. II. Insular (gustatory) cortex', Brain Res, 1998 Jul 27; 800(1): 40-7.
The role of the frontal cortex is unclear: for details, see 12672556, Fresquet N, Yamamoto J, Sandner G, 'Frontal lesions do not alter the differential extinction of taste aversion conditioning in rats, when using two methods of sucrose delivery', Behav Brain Res, 2003 Apr 17; 141(1): 25-34.
A key review, arguing that the amygdala involvement is solely in the process of gustatory neophobia (intimately connected to CTA), can be found in 15893375, Reilly S, Bornovalova MA, 'Conditioned taste aversion and amygdala lesions in the rat: a critical review', Neurosci Biobehav Rev, 2005; 29(7): 1067-88.

Conditioned place preference
An early description of CPP can be found in 7403209, Phillips AG, LePiane FG, 'Reinforcing effects of morphine microinjection into the ventral tegmental area', Pharmacol Biochem Behav, 1980 Jun; 12(6): 965-8.

CPP can be produced by morphine injections into the lateral hypothalamus, periaqueductal gray or nucleus accumbens, but not the caudate-putamen, amygdala or nucleus ambiguus, according to 7116146, van der Kooy D, Mucha RF, O'Shaughnessy M, Bucenieks P, 'Reinforcing effects of brain microinjections of morphine revealed by conditioned place preference', Brain Res, 1982 Jul 8; 243(1): 107-17. Corroborative lesion evidence was presented in, for example, 1830641, Everitt BJ, Morris KA, O'Brien A, Robbins TW, 'The basolateral amygdala-ventral striatal system and conditioned place preference: further evidence of limbic-striatal interactions underlying reward-related processes', Neuroscience, 1991; 42(1): 1-18.
Lesions of the prefrontal cortex disrupt CPP: see 2706078, Isaac WL, Nonneman AJ, Neisewander J, Landers T, Bardo MT, 'Prefrontal cortex lesions differentially disrupt cocaine-reinforced conditioned place preference but not conditioned taste aversion', Behav Neurosci, 1989 Apr; 103(2): 345-55.

Habituation to an Open Field
A good description of habituation to open field, in particular the analysis of results, can be found in 4352216, Tamasy V, Koranyi L, Lissak K, Jandala M, 'Open-field behavior, habituation and passive avoidance learning: effect of ACTH and hydrocortisone on normal and adrenalectomized rats', Physiol Behav, 1973 Jun; 10(6): 995-1000.

Lesions of the caudal pontine reticular nucleus increased habituation in 2634960, Muller G, Klingberg F, 'Lesions of the caudal pontine reticular nucleus reduce spontaneous behavioural activity of rats differently in dorsal and ventral parts of the nucleus', Biomed Biochim Acta, 1989; 48(10): 807-16.
Septal lesions appear to reduce habituation: 12563526, Lamprea MR, Cardenas FP, Silveira R, Walsh TJ, Morato S, 'Effects of septal cholinergic lesion on rat exploratory behavior in an open-field', Braz J Med Biol Res, 2003 Feb; 36(2): 233-8.
Changes in habituation were also produced by lesions of the anterior and posterior nucleus basalis magnocellularis, as well as the vertical and horizontal diagonal band nucleus: 8347801, Klingberg F, Klengel S, 'Lesions in four parts of the basal forebrain change basic behaviour in rats', Neuroreport, 1993 Jun; 4(6): 639-42.
The noradrenergic system does not seem to be involved: see 6440160, Britton DR, Ksir C, Britton KT, Young D, Koob GF, 'Brain norepinephrine depleting lesions selectively enhance behavioral responsiveness to novelty', Physiol Behav, 1984 Sep; 33(3): 473-8.
Cholinergic neurons of the hippocampus and cortex also do not seem to be required for habituation: 3718391, Bailey EL, Overstreet DH, Crocker AD, 'Effects of intrahippocampal injections of the cholinergic neurotoxin AF64A on open-field activity and avoidance learning in the rat', Behav Neural Biol, 1986 May; 45(3): 263-74.

Other Experiments

Documentation

Genetics
Plasticity
Plasticity References
Behaviour
Human Diseases
Proteomics

Summary Statistics
Total Genes	1318
Plasticity Genes	206
LTP Genes	143
Plasticity References	338
Disease Genes in NRC	50
NRC Members	186

G2Cdb - Documentation

Documentation - Behaviour Data

Contents

Overview of the Data

Citation

General Observations

Perceptual Tests

Motor Control Tests

Emotional State/Anxiety Tests

Cerebellar Learning Tests

Amygdalar Learning Tests

Hippocampal Learning Tests

Striatal Learning Tests

Multiple/Undetermined Brain Regions

Overview of the Data

Citation

General Observations

Perceptual Tests

Motor Control Tests

Emotional State/Anxiety Tests

Cerebellar Tests

Amygdalar Learning Tests

Hippocampal Learning Tests

Striatal Learning Tests

Tests requiring Multiple or Undetermined Brain Regions

Documentation