Water Maze Escape Learning Task

Water Maze Escape Learning Task

Physical

Tank (provided by DW lab)

Material polypropylene

Colour white

Diameter 70 cm inside

Height 20 cm

Rim L shaped, 3x3 cm

Water (local tap water)

Depth 15 cm; Volume =15 cm x (35 cm)² = 57,727 cc = 57.7 L

Surface to rim 5 cm

Temperature 25 ± 1 C

Opacity For visible platform task - clear

Reserve tank Start the day with large volume of fresh water kept at about 27 C with Aquarium heater and circulation pump; use this to freshen the swimming tank

Freshness Remove all fecal boli after each mouse

Remove 1 L old and add 1 L fresh solution for each mouse

Platform (provided by DW lab)

Material 1/4" mesh hardware cloth; removable with four nylon screws

painted black for visible platform

Shape Round with 3 cm vertical sides

Diameter 10 cm

Height 0.5 cm above water for visible platform,

Marker Standard tennis ball painted black; on post 4 cm above platform

Location and General Environment

Tank location On board or table about 40 cm above floor; two tanks on one board

[note - they can also be on a table, which will require the camera to be raised]

Separation of tanks White plastic barrier about 80 cm high inserted in wooden base

Illumination (provided by DW lab; local lab must arrange suitable mounting)

One 15 watt frosted "peanut" bulb in aluminum reflector centered over the tank and about 100 cm above it; this applies to the visible platform task; ambient room lighting is needed for the hidden platform task

Brightness at centre about 120 Lux

Light on nearest wall about 80 Lux at edge of tank

Holding during tests Alone in shoebox cage with 3 clean paper towels, top;

it helps to staple the three together along one edge

No food or water during testing

Housing before and after Bring to test room in home shoebox cage with littermate,

bed-o-cob, etc.; put in holding cage in test room

Pretraining

Given about 24 h before training - following all RotaRod testing in previous day; can do two mice at one time, but one mouse at a time is allowed if this can be fit into the work day; requires about 3 minutes for two mice, 1.5 h for all 64 mice when two are tested at once; no measures during this phase; can make notes

2 trials - 15 sec on the visible platform at center of tank; 10 or 15 sec in holding cage; discourage mouse from leaving the platform, if necessary; place back on platform if it leaves

2 trials - 15 sec swimming in an empty tank; start at center, facing away from you; 10 or 15 sec in holding cage; requires more than 10 sec to set up for next phase

2 trials - holding its tail, gently place the mouse in the water with its snout next to the platform so that it scrambles up onto the platform; remain on platform 10 sec; 10 or 15 sec in holding cage; if it tries to turn away from the platform, gently turn it back until it grasps the mesh and climbs up

After the pretraining of a pair, remove boli. No need to freshen tank after each pair.

Training trials

Given to two mice in one session, alternating times as necessary

8 Trials per day

40 sec Time limit per trial (to prevent exhaustion of certain inbred strains)

10 sec on platform after escape

30 ± 10 sec Intertrial interval spent in holding cage; time depends on the behavior of the other mouse, to some extent

Between trials - in holding cage next to tank with top

Randomization of starting locations (N, S, E, W)

Within each block of 4 training trials, each mouse is to be started at each of the 4 points of the compass. These should be determined randomly prior to the start of testing. The easiest way to do this is to get 4 random numbers from a calculator (beware that each series does not begin at the same seed number). Assign the smallest number N, the second smallest S, etc. Write these letters in the column Loc for starting location.

Specific Procedures

Bring mice to the testing room from the housing room:

In the housing room, place each mouse in an opaque plastic holding cage(clear in Portland) with 3 clean paper towels on the floor. These two holding cages should be near the cart. Mouse with tail mark "1" goes in cage 1 for tank 1 and "2" goes in cage 2 for tank 2. Place each holding cage adjacent to the water tank. When all is ready, start the VCR.

Training trial:

1. Pick up mouse by the tail with a gloved hand and place it gently into the water facing the tank wall, at one of four randomly chosen positions (N, S, E, W). A sheet made prior to the session should have the sequence of positions for each mouse to be tested that day.

2. Start the timer when the animal's tail is released. Step back to about 1.2 meter or 4 ft while the mice are swimming.

3. Stop the timer when all four feet are on the platform.

4. Allow the mouse to remain on the platform for 10 sec.; then pick it up by the tail, blot it twice on a paper towel on the table, and return it to the holding cage. If it dives back into the water before the allotted time is up, return it to the cage in the same manner.

5. Record the time to reach the platform, then restart the timer for the intertrial interval. If time allows, make notes on the mouse's behaviour - path type, etc. (Note: If practical, the response time can be recorded during step 4.)

[during the intertrial interval, you may give the other mouse its trial]

On testing two mice at once:

It is not necessary to wait until both mice have completed a trial before starting the next trial for a quick mouse. It may be possible to have two mice swimming at once if they are slow. Practice will be essential for smooth operation of the testing.

After testing of one squad of 2 is completed:

1. Stop the VCR, finish recording all data, and file the data sheets for that squad.

2. Use a standard scoop to remove 1 L of old solution from each tank and dump it into a bucket; when both tanks have been done, dump the bucket down the sink.

3. Search for and remove fecal boli. Use a fine fish net and baster.

4. With another standard scoop, add 1 L of fresh solution to each tank.

5. Return the two mice to their home cage on the cart in the testing room. Reinforce tail marks, if needed.

After a group of 16 mice has been tested:

1. Return the mice to the housing room, then take a break.

2. Check water temperature. Insert a thermometer into both tanks and the fresh water tank. Adjust the temperature of testing tanks to about 26C.

3. Make notes, then get ready for the next group.

At the end of the day

Clean the testing tanks, platforms, and holding cages with gentle detergent and a nylon brush. Rinse with tap water. Dry overnight.

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