Editing Morris water navigation task

{{Short description|Task used in experiments to measure spatial learning and memory}}
{{More citations needed |date=April 2009}}
{{Use dmy dates|date=October 2020}}
[[File:MorrisWaterMaze.svg|thumb|Schematic drawing of the Morris water navigation test for rats. Size and marker may vary.]]
{{Animal testing}}
The '''Morris water navigation task''', also known as the '''Morris water maze''' (not to be confused with ''[[Water maze (neuroscience)|water maze]]''), is a behavioral procedure mostly used with rodents. It is widely used in [[behavioral neuroscience]] to study [[spatial memory|spatial learning and memory]].<ref name="Hooge2001">{{cite journal |last=D'Hooge |first=R |author2=De Deyn, PP |title=Applications of the Morris water maze in the study of learning and memory |journal=Brain Research. Brain Research Reviews |date=August 2001 |volume=36 |issue=1 |pages=60–90 |pmid=11516773 |doi=10.1016/S0165-0173(01)00067-4|s2cid=2651456 }}</ref> It enables learning, memory, and spatial working to be studied with great accuracy, and can also be used to assess damage to particular cortical regions of the brain.<ref name="Hooge2001" /><ref name="Keefe1982">{{cite journal|last=Morris|first=RG|author2=Garrud, P|author3=Rawlins, JN|author4=O'Keefe, J|date=24 June 1982|title=Place navigation impaired in rats with hippocampal lesions|journal=Nature|volume=297|issue=5868|pages=681–3|bibcode=1982Natur.297..681M|doi=10.1038/297681a0|pmid=7088155|s2cid=4242147}}</ref> It is used by neuroscientists to measure the effect of neurocognitive disorders on spatial learning and possible neural treatments, to test the effect of lesions to the brain in areas concerned with memory, and to study how age influences cognitive function and spatial learning.<ref name="Hooge2001" /><ref name="Sharma2010" /> The task is also used as a tool to study drug-abuse, neural systems, neurotransmitters, and brain development.<ref name="Wongwitdecha1996" /><ref name="Mendez2008">{{cite journal |last=Mendez |first=IA |author2=Montgomery, KS |author3=LaSarge, CL |author4=Simon, NW |author5=Bizon, JL |author6= Setlow, B  |title=Long-term effects of prior cocaine exposure on Morris water maze performance |journal=[[Neurobiology of Learning and Memory]] |date=February 2008 |volume=89 |issue=2 |pages=185–91 |pmid=17904876 |doi=10.1016/j.nlm.2007.08.005 |pmc=2258220}}</ref>

== Overview ==
[[File:MorrisWaterMaze.jpg|thumb|A rat undergoing a Morris water navigation test]]
The basic procedure for the Morris water navigation task is that the rat is placed in a large circular pool and is required to find an invisible or visible platform that allows it to escape the water by using various cues.<ref name="Sharma2010">{{cite journal |last=Sharma |first=S |author2=Rakoczy, S |author3=Brown-Borg, H  |title=Assessment of spatial memory in mice |journal=Life Sciences |date=23 October 2010 |volume=87 |issue=17–18 |pages=521–36 |pmid=20837032 |pmc=6457258 |doi=10.1016/j.lfs.2010.09.004}}</ref><ref name="Vorhees and Williams2006">{{cite journal |last=Vorhees |first=C |author2=Williams, M |title=Morris water maze: procedures for assessing spatial and related forms of learning and memory |journal=Nature Protocols | date=27 July 2006 |volume=1 |issue=2 |pages=848–58 |doi=10.1038/nprot.2006.116|pmid=17406317 |pmc=2895266 }}</ref> Many factors can influence the rats' performance, including their sex, the environment in which they were raised, exposure to drugs, etc.<ref name="Wongwitdecha1996">{{cite journal |last=Wongwitdecha |first=N |author2=Marsden, CA |title=Effects of social isolation rearing on learning in the Morris water maze |journal=Brain Research |date=9 April 1996 |volume=715 |issue=1–2 |pages=119–24 |pmid=8739630 |doi=10.1016/0006-8993(95)01578-7|s2cid=12321749 }}</ref> There are three basic tactics for the rats to escape the maze: a praxic strategy (remembering the movements needed to get to the platform), a taxic strategy (the rat uses visual cues to reach their destinations), or spatial strategy (using distal cues as points of reference to locate themselves).<ref>{{cite journal |last=Brandeis |first=R |author2=Brandys, Y |author3=Yehuda, S  |title=The use of the Morris Water Maze in the study of memory and learning |journal=The International Journal of Neuroscience |date=September 1989 |volume=48 |issue=1–2 |pages=29–69 |pmid=2684886 |doi=10.3109/00207458909002151}}</ref> There are a variety of paradigms for the water maze that can be used to examine different cognitive functions.<ref>{{cite journal |journal=Brain Research. Brain Research Reviews |date=August 2001 |volume=36 |issue=1 |pages=60–90 |title=Applications of the Morris water maze in the study of learning and memory |last=D'Hooge |first=R. |author2=De Deyn PP |pmid=11516773 |doi=10.1016/S0165-0173(01)00067-4|s2cid=2651456 }}</ref> In particular, [[cognitive flexibility]] can be assessed using a water maze paradigm in which the hidden platform is continually re-located.<ref>{{cite journal |journal=Journal of Neuroscience Methods |date=May 2011 |volume=198 |issue=1 |pages=44–52 |title=Statistical and theoretical considerations for the platform re-location water maze |last=Saab |first=BJ |author2=Saab AMP |author3=Roder JC  |pmid=21419797 |doi=10.1016/j.jneumeth.2011.03.008|s2cid=33909927 }}</ref>

== History ==
The Morris water navigation task was conceived by [[Richard G. Morris]] (then at the [[University of St Andrews]]) in 1981 as an alternative to the radial maze.<ref>{{cite book |last=Wenk |first=GL |title=Assessment of Spatial Memory Using the Radial Arm Maze and Morris Water Maze |journal=Current Protocols in Neuroscience |date=May 2004 |volume=Chapter 8 |pages=8.5A.1–8.5A.12 |pmid=18428607 |doi=10.1002/0471142301.ns0805as26 |isbn=978-0471142300 |s2cid=205151857 |editor=Jacqueline N. Crawley |editor-link=Jacqueline Crawley |display-editors=etal}}</ref> The test was developed to study spatial learning and how it differed from other forms of [[associative learning]].<ref name="Morris1984">{{cite journal |last=Morris |first=R |title=Developments of a water-maze procedure for studying spatial learning in the rat |journal=Journal of Neuroscience Methods |date=May 1984 |volume=11 |issue=1 |pages=47–60 |pmid=6471907 |doi=10.1016/0165-0270(84)90007-4|s2cid=8292701 }}</ref> Originally rats, now more commonly mice, were placed in an open pool and the latency to escape was measured for up to six trials a day for 2–14 days.<ref name="Morgan2009">{{cite journal |last=Morgan |first=D |author2=Buccafusco, JJ |title=Water Maze Tasks in Mice: Special Reference to Alzheimer's Transgenic Mice |year=2009 |pmid=21204327}}</ref> Several variables are used to evaluate an animal's performance. For example, a "probe trial" measures how long the test subject spends in the "target quadrant" (the quadrant with the hidden platform).<ref name="Morgan2009" /> More elaborate trials alter the location of the hidden platform, or measure distance spent swimming in the pool before reaching the platform.<ref name="Morgan2009" /> Over the years, many different versions of this test have been performed with a large amount of variables. For example, neuroscientists examine the effect of differences of sex, weight, strength, stress levels, age, and strain of species. The results vary dramatically, so researchers cannot draw conclusions unless these variables are kept constant.<ref name="Hooge2001" /> Many different size pools have been used throughout the history of this task, but it has been shown that this does not have a significant impact on the results of the test.<ref>{{cite journal |last=Van Dam |first=D |author2=Lenders, G|author3=De Deyn, PP |title=Effect of Morris water maze diameter on visual-spatial learning in different mouse strains |journal=[[Neurobiology of Learning and Memory]] |date=March 2006 |volume=85 |issue=2 |pages=164–72 |pmid=16290194 |doi=10.1016/j.nlm.2005.09.006|s2cid=19824659 }}</ref> In early versions of the task, researchers only timed latency to escape, however video tracking devices are now routinely used to measure the path to escape, time spent in each quadrant, and distance traveled in the pool.<ref name="Terry2009">{{cite journal |last=Terry AV |first=Jr |author2=Buccafusco, JJ |title=Spatial Navigation (Water Maze) Tasks |year=2009 |pmid=21204326}}</ref>

=== Original experiment ===
In Morris' first experiment, the apparatus was a large circular pool, 1.30 m across and 0.60 m high. The purpose of the original experiment was to show that spatial learning does not require the presence of local cues, meaning that rats can learn to locate an object without any auditory, visual, or olfactory cues.<ref>{{cite journal |journal=[[Learning and Motivation]] |author=Morris, R.G.M. |title=Spatial localization does not require the presence of local cues |volume=12 |issue=2 |pages=239–260 |date=May 1981 |doi=10.1016/0023-9690(81)90020-5 }}</ref>

== Analysis ==
The earliest measure of learning is ''[[Latency (engineering)|escape latency]]'', which is the time it takes to find the platform. However, this measure is confounded by swimming speed, not necessarily a cognitive factor, and path length between point of origin and platform is a parameter more closely related to spatial learning.<ref name=Wolfer /> Further parameters are the Gallagher measure,<ref>{{cite journal |vauthors=Maei HR, Zaslavsky K, Teixeira CM, Frankland PW |title=What is the Most Sensitive Measure of Water Maze Probe Test Performance? |journal=Front Integr Neurosci |volume=3 |pages=4 |year=2009 |pmid=19404412 |pmc=2659169 |doi=10.3389/neuro.07.004.2009 |doi-access=free }}</ref> the average distance to the platform, and the Whishaw corridor test,<ref name="Whishaw1985">{{cite journal |last1=Whishaw |first1=IQ |title=Cholinergic receptor blockade in the rat impairs locale but not taxon strategies for place navigation in a swimming pool. |journal=Behavioral Neuroscience |date=Oct 1985 |volume=99 |issue=5 |pages=979–1005 |pmid=3843314 |doi=10.1037/0735-7044.99.5.979 }}</ref> which measures time and path in a strip directly leading from swim-start to platform. Other parameters are measured during probe trials: the escape platform is removed and the mice or rats are allowed to search for it for a fixed time (often 60 seconds). Variables measured are time and path length in quadrants, time near platform, and platform crossings.

== Comparison to maze tasks ==
{{see also|Oasis maze}}
Like other spatial tasks, such as the [[T-maze]] and [[radial arm maze]], the Morris water navigation task is supposed to measure spatial memory, movement control, and [[cognitive map]]ping.<ref name=Whishaw /><ref name=Crusio>{{cite book |last=Crusio |first=Wim |title=Handbook of molecular-genetic techniques for brain and behavior research |year=1999 |publisher=Elsevier |location=Amsterdam |isbn=978-0-444-50239-1 |pages=638–651 |edition=1st |author-link=Wim Crusio |editor=Crusio, W.E. |editor2=Gerlai, R.T. |editor2-link=Robert Gerlai |chapter=Methodological considerations for testing learning in mice}}</ref> The T-maze and radial arm maze are much more structured in comparison.<ref>{{cite journal |last=Hodges |first=H |title=Maze procedures: the radial-arm and water maze compared |journal=Brain Research. Cognitive Brain Research |date=June 1996 |volume=3 |issue=3–4 |pages=167–81 |pmid=8806020 |doi=10.1016/0926-6410(96)00004-3}}</ref> The T-maze, for instance, only requires the rat or mouse to make a binary decision, choose left or right (or East or West). In the Morris water navigation task, on the other hand, the animal needs to decide continually where to go.<ref name="Morris1984" /> Another reason this task became popular is that rats (but not mice)<ref name=Whishaw>{{cite journal |last=Whishaw |first=I.Q. |title=A comparison of rats and mice in a swimming pool place task and matching to place task: some surprising differences |journal=[[Physiology & Behavior]] |year=1995 |volume=58 |pmid=8559777 |doi=10.1016/0031-9384(95)00110-5 |issue=4 |pages=687–693|s2cid=11764808 }}</ref> are natural swimmers, but dislike colder water (mice simply dislike water of any temperature), so in order to perform the task they do not need to be motivated by food deprivation or electrical shock.<ref name="Morris1984" /> The mobility of the platform allows for experiments on learning and relearning.<ref name="Terry2009" /> Also, the apparatus set-up and costs are relatively low.<ref name="Terry2009" />

== Weaknesses ==
When the searching times for the platform in the target quadrant are reduced in the probe trial, this is seen as direct evidence that the spatial memory of the rat must be impaired. However, many times the reason for a lengthier amount of time spent looking for the platform, or the lack of searching in the target quadrant, has nothing to do with an effect on the rat's spatial memory, but is actually due to other factors. A large study of performance in mice concluded that almost half of all variance in performance scores was due to differences in [[thigmotaxis]], the tendency of animals to stay close to the walls of the pool. About 20% of the variability was explained by differing tendencies of mice to float passively in the water until "rescued" by the experimenter. Differences in spatial memory were only the third factor, explaining just 13% of the variation between animals' performance.<ref name=Wolfer>{{cite journal |last=Wolfer |first=DP |author2=Stagljar-Bozicevic, M |author3=Errington, ML |author4= Lipp, HP  |title=Spatial Memory and Learning in Transgenic Mice: Fact or Artifact? |journal=News in Physiological Sciences |year=1998 |volume=13 |issue=3 |pages=118–123 |doi=10.1152/physiologyonline.1998.13.3.118 |pmid=11390774|s2cid=10771826 |doi-access=free }}</ref>

==See also==
*[[Oasis maze]]
*[[Barnes maze]]
*[[Elevated plus maze]]

==References==
{{Reflist}}

{{DEFAULTSORT:Morris Water Navigation Task}}
[[Category:Animal testing mazes]]
[[Category:Behavioral neuroscience]]