water maze - watermaze - video tracking - water maze - Morris watermaze
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by HVS Image - video tracking for Morris watermaze
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I General Information
watermaze was devised by Prof Richard Morris (RGM Morris) nearly 30 years ago. It continues to be popular; in fact we think its use
is increasing. It is about place-learning and memory.
are natural swimmers. They want to get out of the water, but swimming does not
distress them. Two advantages of Morris water maze over others mazes are:
The rat wants to get out, so it searches - it does not wait about.
In water there are no local cues (e.g. scent trails).
Morris water maze consists of a round tank (pool) of water. We think that 6ft
(1.8m) to 2m diameter is good. We think that a 2 ft (0.6m) deep pool is good, with 1 ft
water. For mice 5-6ft (1.5-1.8m) diameter is good, and the same 2ft deep. We
think that is good to place the pool on a 1-2ft base, to make working more
convenient. The escape platform can be 4ins (10cms) in diameter . The
platform should not be too close to the side, or the rat finds it just by
circling around the pool-side. For rats the platform can be 1/4 in below the
water. For mice it should be very close to the surface.
are told that a good water temperature for rats is 26 deg C ±2 deg. Colder
encourages activity, but can cause hypothermia, which impairs learning.
think that the best rats are hooded. These are the same as those used by Morris. Hooded rats are easy to track. The tracker detects the black hood. HVS
is like other systems, it tracks contrast. For the same reason, dark-colored
mice track well. Your pool and platform are white. You make the water white,
e.g. with skim milk powder (this is to stop the rat from seeing thru the water).
think that hooded rats perform better than white (albino) rats, possibly because
albino rats do not see as well. Another problem with albino rats: to get
contrast for tracking, the pool has got to be black with clear water. Black
pools cause tracking problems, because they reflect lights. But it can be done.
(See set-up hints in this document).
is an (escape) platform. This is white (or clear Plexiglas) for awhite pool. During the training
phase you can allow the platform to be ~ 1/2" above the water, and you can
paint the side black. This trains the rats, that there is a platform, and that
is how to get out of the water. This is important - they have got to know this
before any place-learning can happen.
you put the rat into the water, support it in the hand and gently lower it into
the water with the tail-end lower, so the
head does not go under water. Dropping them in head-first stresses them, which
impairs learning. Usually they are put in with the head pointing towards the
pool-side, to minimize bias.
first the rat will swim around the side. After a while it understands there is
no way out by doing that. Then it searches more to the center. If it does not
find the platform after approximately two minutes, lift it out & dry it. If
it really does not get the point, you can gently guide it to the platform. It
gets on the platform & usually rears and looks around.
This is something else to learn, that there is an escape platform.
can leave it for ~ 15 seconds, to orientate. It is looking into the room. There
must be visual cues on the room walls. It needs at least 3 different cues, e.g.
3 different posters, (so it can 'triangulate'), always visible from inside the
pool. These cues should be extra-maze i.e. well outside of the pool. If they are
close to the poolside, then the rat could be doing association between the cue
& the platform.
some training swims, the rat will go direct to the platform. After ~15 seconds
you lift it off the platform and gently dry it (better - put it in a litter of
tissues, so it can dry itself). Rats can do several swims per day.
you can use a different start-point. An informed rat does not try to back-track
to the old start point. It goes direct to the platform. Because it has a spatial
map in its hippocampus?
training sequence and test sequence are something that you as the scientist have
to decide on. Obviously you are going to use Controls and Experimental rats.
Rats can cheat! Instead of learning where the platform is, they can learn search
strategies. E.g., swim around at some distance from the side, or guess where the
platform is, and make a series of sweeps. A good analysis program helps you distinguish this
from spatial learning.
trials: There is no platform. The trial ends after 1-2 mins with you
rescuing the rat. Only do this on trained rats, and not too often. Done at the
start, it tests for spatial bias. Done at the end of training, it tests the
rat's spatial learning.
are solid citizens. They are quite willing to swim to that platform, get on it,
and orientate. Mice are also natural swimmers, but they are altogether more
frisky & temperamental - please refer to HVS Image Mouse Notes.
Copyright (C) 1998 RA & HVS.
thanks to Dr Richard Anderson (UK) for this. Edited by HVS.
can examine reference learning and memory in the Morris water maze. Initially
the mice are trained to locate a cued, flagged platform. During this phase of
the study both the cued platform position and the starting position of the mouse
are randomly varied to avoid habituating the mouse to a particular area of the
this sensory motor test the cued platform is switched with a submerged platform
the position of which is fixed for each mouse. As the mouse learns its position
the path-lengths & latencies to locate the platform are reduced.
the final placed session, the platform is removed and the swim-pattern of the
mice is tracked for one minute. We then compare the time the mouse spends
swimming in the former platform quadrant with the time in the other three.
gives a measure of memory and also allows us to see if the mice are using
different strategies to find the platform. For example, instead of using the
distal cues, some mice learn to swim at a fixed distance from the edge of the
pool until they find the platform.
additional HVS measure one can take includes the number of platform position
crossings. Again if the mouse shows good evidence of spatial memory the mouse
will exhibit a significantly increased number of former platform position
crossings in comparison with the other three.
further advantage of this model is that by reversing the submerged platform
position, it allows us to examine flexibility of learning, i.e. how easy is it
for the mouse to let go of one learned behavior and acquire the new task.
Inflexibility of learning is an early feature of AD dementia.
looking for statistical differences in latencies, pathlengths and swim speeds
one uses repeated-measures analysis of variance (ANOVA).
a significant overall main effect of treatment, genotype etc. one can employ
post hoc comparisons e.g. Dunnett's test. For probe data one-way ANOVA is
Size of pool &
are a matter of personal choice. One criterion, which sounds logical, is that
the task should not be so easy that it can be achieved mostly by chance. I.e.
the pool should not be too small, nor the platform too big.
if the pool is too small, the platform might be close to the sidewall. In that
case, just swimming around at a fixed distance from the sidewall will find the
adult rats a pool diameter if 1.8m (6ft) may be good, with a 10cms (4 ins)
diameter platform. Depth ~ 60cms (2 ft). In the US we supply pools 4, 5 or 6ft
diameter, 2 ft deep, with a 1ft water-depth.
mice a pool diameter of 1m to 1.5m is used, with platform diameter 5cms to 10
cms. Pool height ~30 cms, water depth ~ 25cms works.
are very aware of the room & operator, and a sidewall above water level
could help block the line of sight. With all animals, it is vital that they can
see the cues (on the lab walls), from the vicinity of the platform - otherwise
they can't orientate.
all labs use round platforms - this sounds good, as there is no preferred
direction for approach. A few use square platforms - please note that HVS Water
software is designed for round platforms.
/ Water maze Hints
Copyright (C) 1998 R.J.Morris and HVS Image.
Rats are natural swimmers and if handled well will cooperate easily in Water
Maze. They don't have the option to float or jump - they are solid citizens who
just swim for that platform and get onto it.
b) Mice are also good swimmers, and if
handled well, will also take part easily. But they are more temperamental, and
they do have the option to stop swimming and just float, and to jump. These
notes suggest ways to reduce stress, so your mice will feel confident, and
following notes are edited from material kindly supplied by Dr. Roger Morris.
swimming-pool (Morris Water Maze) is a delicate balance of motivation provided
by stress/reward, and a difficult task. It is an unnatural for rodents, for whom
sight is a minor sense. If the stress is too high, or the reward too slight, the
task is not attempted.
Platform & Water
Cover the platform with a fibrous mesh into which the mice can dig their paws
and feel secure when they get there. We found a synthetic underlay (to stop
carpets slipping) ; it is whitish and blends with the water (milk). Others have
used pot-scouring pads.
Make the water just cover the platform by ~5mm. Rats are big enough to feel they
are out of the water. Mice are smaller; 1-2 cms is too much.
Water-temperature has to be accurate to 1 deg; we use 24 deg C. A couple of
degrees colder and they just climb out
Time On Platform &
Time on platform has to be sufficient for them to adjust to the feel &
location, and to see where they are. However the prime reward is not to climb
onto the platform, but to leap into your arms when you intervene to rescue them.
So keep it to 10 seconds before you are seen or heard coming to the rescue.
And they do leap ! You need the pool to be sufficiently high-sided to stop them
leaping out into the room. The high-side requirement is a major determinant of
water level & location of cues.
Because rescue by you is the reward, you will never train them while you are
detectable by sight or sound. The task has to clearly direct them first to the
Must be visible, & useful to mice. They must be far enough away to require
the mice to use spatial analysis, rather than association, to solve the task.
But near enough & positioned appropriately, for the mice to see and use
them. And spatially specific enough to solve a spatial task. Feel-good
psychedelic & animal posters stuck on the far walls of a large room ,below
the line of vision of mice swimming in a high sided pool, do not qualify!
We use a 2m pool, sufficiently large that I only have to place the cues just
outside the walls of the pool, and the platform ~0.5m in from the side. That
makes the task difficult – impossible to solve by association, and the cues
are maximally visible. Although it is still obvious that mice placed near the
walls have to swim to the centre to get their full bearings. There are places
near the wall of the pool, where they can see 1 or 2 cues, but need all 3 to
triangulate the position of the platform.
For a 1m pool you have to place the cues some distance from the pool, for the
task to be spatial not association. I use board 5-15 cm wide, 1m long,
can consist of black stripes (vertical, horizontal, triangles) of different
need to stand out to a mouse, be positioned where they are optimally visible
& angled towards the centre of the pool so they appear perpendicular to the
mouse. And instantly distinguishable from each other. You can see if the mice
are using them; they need 3 specific cues, and diffuse cues in the room, such as
sources of light, as general orientators.
Time & Intervals
We use 2 mins in a 2m pool with a 15 cm platform*. If your pool is as small as
1m, I would swim them for 1 min, & when they fail to find the platform,
guide them to it so they climb on. Ideally you leave them there for 10 seconds,
so they assess the surroundings. In practice they will make a leap for it if you
let them. So as they climb on, step well-back & try to ensure they stay on
for 10 seconds. If they immediately take to the water & keep swimming,
intervene again to guide them back. They have to learn that rescue is dependent
on staying on that platform.
If they leap for you before you retreat, you may as well catch them, as at least
they have got the idea. You should find that on the first day your mice mostly
fail to find the platform. Then on subsequent dates their efforts are greeted
with increasing success. If you leave them too long at the beginning, swimming
around without success, they will associate the swim with failure & panic.
We find that mice given 2 trials per day learn nearly as quickly as 4 times a
day. If you are worried about the stamina of elderly mice*, cut back to 2 per
day. Our mice look forward to their swim (they rattle the tops of their cages
when my postdoc comes to collect them). We suspect they possibly enjoy it too
much, and extend the swim-time because the alternative is to go back in a boring
cage. Then we tried lowering the temperature of the pool by 2 deg, and they went
on strike ! What I was leading-up to is that if the mice are not panicking, I
suspect the swim is not traumatic, and they enjoy doing laps of the pool.
Intervals between swims is important. We use 30 mins, as being a good way to
We give them 2 days in the test room, playing with them in & out of their
cages, so they are comfortable with us and the room, before starting swimming.
They have also been handled by us intermittently since birth, so they are happy
Smells are very important. Even subtle amounts of perfume can confuse !
"bad" smells are totally out, e.g. rats & especially cats. If you
have a pet cat, it might just work if you shower & change into fresh clothes
at the lab.
1. HVS can supply a Plexiglas platform, good for white
& black pools.
10 cms, with a cross-hatch of lines on the top to reduce slipping (so hopefully
you don't need pot-cleaning pads.
24 deg C is cooler that the average rat-pool (26deg C).
More than one Morris!
a. R.J. Morris (Dr Roger
Morris) kindly provided this mouse-info.
b. R.G.M. Morris (Prof
Richard Morris) -invented the Water Maze technique.
Metric/imperial conversions: 1 inch= 2.54 cm; 12 inches = 1 foot (ft)
Part II HVS User Hints
maze etc - Safety hints
Suitability for use.
HVS Image system is for research use only, e.g. Morris water maze
using rodents. It is not suitable for clinical, diagnostic or therapeutic use
with human subjects. It does not comply with electrical isolation regulations
for clinical equipment, and must not be attached, directly or indirectly, to
safety. There are no user-serviceable parts inside the HVS tracker-components -
for safety reasons do not open-up the components. Do not open-up the PLUS
modules. Follow manufacturer’s advise regarding notebook PCs.
• In the U.S. we provide galvanized tanks for use as water maze pools. We
are advising you to apply metal primer paint before painting them white or black
inside, so the white & black paint do not peel off. Regarding this primer
paint, a U.S. user has suggested it is toxic, though OK if painted-over. In our
view, not as paint experts or toxicologists, primer paint has to be somewhat
corrosive because it has to 'bite' into the metal surface to form a bond. But it
should not contain any long-term toxins e.g. heavy metals. We have a statement
from Hammerite paints that their Special Metals Primer gives-off fumes such as
nitrogen oxides while drying, but it is Not Classified for regulatory purposes
in the UK, but please don't dispose of it down drains. We recommend you get a
statement from your supplier regarding the primer you use.
• Health and safety are vital issues in "water maze" as in all
lab work. Users please consult your Health & Safety advisor before
setting-up and using your water system. Institutions may wish to make a Risk
Assessment. Disclaimer: HVS is not an advisor, but we do care about your health
& safety, and here we point-out items for especial attention:
• When fixing and adjusting the overhead camera, absolutely do not climb on
furniture. If your safety officer approves, use a properly secured ladder.
conducts electricity - even more so the galvanized tank (pool) we supply in the
US & Canada ! You are planning to put your hands in the water while standing
on a wet floor. Your electricians may want to earth-connect the tank. Please
show them your setup before you apply power and start working.
supply & drainage pipes should not project from the side of the pool, or
present a trip hazard. Drainage can be thru the pool base.
maze can involve repeated reaching-out and leaning-over movements. Also it can
involve long periods of solitary repetitive work without daylight. These remarks
apply especially to commercial labs where high throughput and experiments
lasting months or years occur. In terms of reaching or bending we distrust pools
of diameter greater than 6ft (1.8m) and pools resting on the floor - our best
guess is that an HVS pool should be set on a base 12ins (0.3m) high.
& safety hints from users are welcome & can be received in confidence.
How to set up your
2020 Plus system
the latest setup info, contact HVS
Image and request access to User-Information website.)
Video recording is optional:
• 1) Use a VCR in the output cable from the camera.
• 2) We plan to put a button in the 2020 (Plus) software
• so you can record short sequences to the PC hard disk.
How to light the
• For white pools use 2 fluorescent strip
lights. Modern compact strip lights are more intense - please use a
• Following our cooperation with Reneuron UK,
an improved setup is recommended for black pools, which avoids reflections. Use
the set-up shown above right. Use 4 up lighters. Use lamps of ~ 60 watts, not
powerful lamps. The lights should be fixed high enough that they are not seen by
the camera, e.g. 6ft from floor. If the camera sees lights, reflections will be
created within the lens.
probe test: is it always a measure of spatial memory for transgenic mice?
1999 Dr Roger J Morris, UK & HVS Image
aim, in the watermaze, is to test the capacity of rodents to learn, and
retrieve, spatially-encoded information; instead we are restricted to asking the
mice to solve a problem for which the ability to learn and remember a
spatially-cued task will significantly enhance performance.
is the capability for spatial learning the main variable in this test?
Experience suggests that two problems in particular are worth considering,
especially when dealing with transgenic mice.
first is the ability of the animal to concentrate upon the task in hand. If the
mice are too nervous, or too weak to be at their ease swimming, their
performance is compromised independently of spatial learning (both effects have
misled studies of spatial learning in transgenic KO mice). It is important that
mice be tested in appropriate assays to determine whether they differ
significantly from the control group in levels of anxiety, willingness to
explore new territory, and general locomotory activity. The latter is monitored
in the watermaze as swimming speed, the former given by such assays as the
elevated plus maze, holeboard and open field. Our experience suggests that
problems in the watermaze such as thigmotaxis and passive floating are minimized
if mice first get accustomed to being removed from their home cage to solve
relatively unthreatening problems, before being placed in a large tank of water
with no visible means of escape. Thus both practical and theoretical
considerations suggest testing the mice for exploration/anxiety prior to the
watermaze, and the results may advise against using the watermaze as a test of
second concerns the strategy used by the mice to locate the platform. Have they
solved the problem purely by reference to the spatial cues, or has the physical
process of "swimming in the general area until bumping into a submerged
object" been a significant part of the strategy? In the initial phase of
the watermaze in which rodents search for the hidden platform, in each trial the
rodent has only to bump into the platform once to locate it and escape; is this
single encounter the result of remembering how to triangulate the location from
external cues, or just good luck?
the methods devised to eliminate a 'lucky bump' from the analysis, the probe
test is considerably the least expensive and most convenient, and works very
well for rats. A rat, knowing that the platform was in a certain position, will
trawl repeatedly over that position looking for it. The rat is thus indicating
that it knows the position independently of such tactile cues as hitting the
platform, and this is real knowledge rather than a chance passage through the
target area. This simple test is conducted when the animals have learnt the
straight forward task of locating the hidden platform; i.e. when their elapsed
time to find the platform has dropped from an initial maximum (e.g. 90 sec for
the trial) to a base level where no significant improvement is occurring each
day (generally around 10-25 sec, depending on the size of the pool/platform).
test, however, depends as much upon the rodent's strategy in solving a problem
as do the initial searches for the hidden platform; but in the probe test the
problem is one of spatial memory if, and only if, the rodent does not confront
the fact that the platform is no longer there. If the rodent realizes that the
platform really is not there, that the hitherto reliable spatial analysis will
not enable it to escape the water, then its subsequent behavior cannot be
interpreted as driven by spatial analysis. It will resort to alternative
survival-dependent problem solving. If the mutants differ from the controls in
levels of anxiety, or in other less readily identifiable variables (depression,
quick-wittedness, etc), their response to finding that the platform has been
withdrawn will almost certainly vary from that of the controls.
find that mice tend to be much more adaptable than rats upon finding that the
platform has gone. Our mice swim immediately to the former position of the
platform. A significant number then swim back to where they were put into the
pool (which is randomly varied trial by trial, but they relocate this point
accurately) and swim back to the former position of the platform. Some even
repeat this once more. Most spend some time swimming around in the central 70%
of the pool trying to locate the platform (and will again cross the former
position). At some stage, many head for the side of the pool from which they
will be retrieved at the end of the trial, where some float. After 90 sec, they
escape the pool - confirming the non-spatial experience of the previous trials.
most mice return more than once to the former platform position, the groups
under test will often spend significantly more time in the former quadrant, and
pass over the former position of the platform, than they will in control
quadrants/counters. The probe test thus works in mice as well as rats. Where a
mutant group of mice differ from the control group in this test, I suspect that
in some cases the source is not a defect in spatial memory, but differences in
survival strategy by rodents that realize spatial memory will not help them
escape from the water. The frequency with which defects are only found in the
probe test, but not in the initial searching, concerns me since in very few
cases are potentially confounding properties such as anxiety investigated.
adaptability of the mice to variation of the test can be assessed if one
reverses the position of the platform. On the day following the probe test,
return the platform to the pool, but in a new position. Start the mouse off by
placing it for 15 sec on the platform in its new position, so it knows there is
again a platform to find, but (if it learns quickly) in a new position. Then run
a series of trials for the mouse to find the platform in its new position,
comparing not only time/path, but passages through counters and time in
quadrants as simple indicators of strategy. We have found that mice of one
knockout strain, on the first day of platform reversal, return immediately to
the former site of the platform, and then begin a circular search pattern for
the new location (which is usually successful within 90 sec); their wild type
littermates tend to restrict their search mainly to the former position of the
platform, and only after two futile trials do they begin to search more widely
to find the platform. By trials 3/4, both groups are equally successful in
finding the platform in its new position. The genotype-specific difference seen
on day 1 of reversal is, I suggest, one of survival strategy, not spatial
in summary, how the rodent solves any of the problems confronting it in the
watermaze depends not just on its capacity for spatial learning, but also its
strategy for solving problems; as these problems are varied (probe vs. hidden
platform), it may be a difference in strategy, rather than in learning or
memory, that dominates the response of knockout, compared to wild-type, mice. I
must also state that this is not a common view in the field - the probe test,
after all, has proved to be one of the best ways for producing a significant
difference in behavior between control and mutant groups, and the temptation to
attribute this difference to defects in spatial learning is rarely resisted.
It is my opinion that, given the
unknown effect of most mutations upon the emotional, sensory and cognitive
functions of the mice under test, the prime test of spatial memory is given by
the initial search for the hidden platform, provided this is set up
appropriately. That is, the initial search must be set up so that the animal
realizes early on that the problem is difficult but solvable (avoiding problems
of thigmotaxis and floating); the learning curve must show progressive
improvements in performance over many trials (thus canceling out the "lucky
bump"); and the mice should not be overtrained. And above all, the mice
must be physically and emotionally able to perform the task.
Watermaze breaking ....
American Journal of Obstetrics & Gynecology -
Fulltext: Volume 199 ...
Learning evaluation began after 3d using the Morris watermaze and T-maze. The
cortex and hippocampus were isolated and calibrator-normalized relative rt-PCR
.. Spatial memory in the Morris water maze and activation of cyclic ...
Spatial memory in the Morris water maze and activation of cyclic AMP response
element-binding (CREB) protein within the mouse hippocampus ...
Sex differences in water maze performance and cortical ...
Herein we demonstrate that Lhx7 null mutants display a sex-dependent impairment
in water maze, with females appearing more affected than males. ...
Mu opioid receptor knockout mice in the Morris
Water Maze : a ...
To substantiate this difference further, MOR knockout mice and wildtype
littermates were tested in the Morris Water Maze (MWM), which allows for testing
Program in Biomedical Science: U-M Medical
Neurobehavioral assessment tools that are sensitive to changes in severity of
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Spinal Cord Lesion Study - OpenWetWare
MORRIS WATERMAZE TEST OF COGNITIVE FUNCTION. The MWM will evaluate the animals'
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Behavioural Pharmacology - Fulltext: Volume 18(8) December 2007 p ...
The effect of (±)-CP-101 606, an NMDA receptor NR2B subunit selective antagonist
, in the Morris watermaze. Eur J Pharmacol 476:193-199. ...
Robotics Institute: The role of the hippocampus
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A.D. Redish and David S. Touretzky, "The role of the hippocampus in the Morris
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Cornwell BR, Johnson LL, Holroyd T, et al. Human hippocampal and parahippocampal
theta during goal-directed spatial navigation predicts performance on a virtual
Morris water maze. J Neurosci. 2008 Jun 4;28(23):5983-90. [Abstract]
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Briefly, animals learned to escape a pool of opaque water (similar to that used
in the Morris water maze) by swimming to one of two visually distinct cues. …
Three distinct visible cues were used [plastic cylinders painted either solid
The Neurocritic -
With acknowledgements to Dr Van Dam,
this abstract is here for a
limited time, no authority to copy,
for info of neurosciences
Effect of Morris water maze diameter
on visual-spatial learning in
different mouse strains.
Laboratory of Neurochemistry and
Behaviour, Institute Born-Bunge,
Department of Biomedical
Sciences, University of Antwerp,
Universiteitsplein 1, 2610
Find all citations
in this journal
The Morris water
maze task is a
widely used tool to
upon several factors
including not only
the traits of the
but also apparatus
present study aimed
at investigating the
effect of maze
performance in three
BALB/c, and 129/SvEvBrd
Three maze diameters
(150, 120, and 75
cm) were used under
and stress levels,
did not allow BALB/c
commonly known as
poor learners, to
satisfactory in all
three maze settings,
with superior probe
trial performance in
downscaling of maze
even render this
task too simple for
this strain. If the
background strain is
abilities should be
performed in a small
sized MWM pool, as
adequately in the
is drawn to the
supplying a detailed
one strain to
another and from
data obtained with a
specific strain and
maze diameter to
dimensions should be
dealt with very
importance of a
choice of background
strain and water
plan to investigate