Planning your first water maze experiment

Morris water maze in eight steps

Calibrate the pool, check the lighting, set the threshold, run, then analyse into a SUM and a CST file.

1. Fill the pool (normally 30 cm deep) and plug the camera in before you start HVS Image.
2. Click ‘Morris Water Maze’ and make sure the ‘Barnes’ box is not ticked.
3. Click ‘CALIBRATE’, enter the pool and target diameters, click the North, South, West and East edges of the water surface, then calibrate every platform position you may use (centre first), and click ‘Save and Return’.
4. Click ‘CHECK LIGHTING’ and adjust your lights until no shadow or glare dots remain.
5. With an animal in the pool, start the ‘THRESHOLD’ at 100 and adjust until the cross follows the animal everywhere.
6. Enter ‘Max Seconds’, choose ‘Single Trial’ or ‘Series of Trials’ and an ‘Auto-end on platform’ option, then click ‘PREPARE’ and line up the platform with the on-screen circle.
7. Click ‘RUN’ just as you release the animal; click ‘END’ to stop early.
8. Click ‘ANALYZE’, highlight the trials, name your SUM file in ‘Name your Summary (SUM) file’, click ‘Analyze Batch or Series’, then use ‘Export Results / Setup Custom’ to make your CST.

Water maze checklist

Tick these off before your first trial and during each session; they catch most tracking problems before they cost you data.

Before the first trial

• Camera plugged in before you start HVS Image.
• Camera positioned so the pool surface almost fills the view; camera settings unchanged since calibration.
• ‘Barnes’ is NOT ticked.
• Pool calibrated by clicking North (top), South (bottom), West (left), East (right), with every platform position you may use.
• ‘CHECK LIGHTING’ shows no white dots (shadow, on a white pool) or red spots (glare, on a dark pool).
• Threshold set with an animal in the pool so the cross follows it everywhere.
• Other programs closed and antivirus scans scheduled outside tracking times.
• Remote or mouse clicks reliably once (a faulty or low-battery mouse can double-click).
• Water depth, temperature and opacity: recorded and kept the same for every session.
• Distal cue arrangement as for the rest of the study: checked from the animal's viewpoint before each session.

Every session

• ‘Max Seconds’ and the ‘Auto-end on platform’ option match your protocol.
• Correct ‘Platform Number’ (a calibrated number) and start point, or the right TXP file selected.
• After ‘PREPARE’, the real platform lines up with the on-screen indicator circle.
• Click ‘RUN’ just as you release the animal, working from the south (bottom of screen) side.
• Probe trials: learned platform number entered, ‘Probe’ ticked, ‘Auto-end on platform’ set to ‘No’.
• Unwanted .hvs files moved out of the HVS folder; .hvs and .sum files backed up.