Morris Water Maze Solutions

Morris Water Maze comprises a number of components

You need: 1 a pool or tank; 2 cues; 3 platforms; 4 a tracking system including computer(s), software, actuators(s) and camera(s); 5 analysis software

The Morris Water Maze Pool

Sized specifically for rats or mice, the Morris water maze tank should have no visible cues such as seams. These are common on inferior commercial and home made pools or tanks and will completely invalidate experiments as they will provide local cues. Steel tanks may dent, chip or corrode providing cues to the animals in the tank and are cumbersome to handle in the laboratory. Over thirty years of experience in hundreds of labs have optimised the HVS Image Water Maze Tank to overcome all these problems. The HVS Image Water Maze Tank is constructed of high performance, high strength odor neutral Co-Polymer Polypropylene (CPP) which has an excellent strength to weight ratio and a hard glossy easy to clean surface. It is raised on easy glide high performance swivel/lock casters for maximum performance and safety. Standard hardware store castor may hold up a partly filled tank if you don’t lean on it, but an overfilled full water maze pool can exceed 1.5 tonnes weight and may collapse standard castors catastrophically. HVS Pools use a castor system that incorporate a 100% safety margin and allow for the fact that experimenters may occasionally lean on or support themselves on the full pool. Experience has show that castors that do not have a suitable lock facility will allow the tank to move slightly, changing calibration without the experimenter being aware and ruining whole runs or seasons of experiments, so HVS Image pools use a special castor locking system to prevent this. And of course castors that project beyond the pool are a tripping and injury hazard not to mention the fact that they make the experimenter lean in a position which is unacceptably unergonomic in a field where back problems are are already endemic. We find that unacceptable and do everything to mitigate such problems and we think that you should accept no less.

Remember that the pool temperature is crucial. It is not just an environmental factor, but is actually the aversive stimulus in Morris water maze. It should be 21°c for rats and 26°c for mice. While pools can be heated by starting with warm water each day, if it varies through the day, so will the experimental results. HVS Image can provide water heaters with tanks to prevent this happening.

Cues for Morris Water Maze

To ensure that you are actually testing spatial learning the correct cue sets must be used. It is essential to have the right distances or you will confound measurements by using egocentric navigation (which encodes routes and paths and procedural memory) rather than allocentric navigation for which you need truly distal cues. The HVS Image Cue system ensures that this distinction is made clearly and consistently across labs and that cues are distinct to the rodent’s visual system.

Platforms for Morris Water Maze

HVS Image can provide a number of types of platform. These can be either fixed or rising platforms, sized for mice or rats.

Platforms can be fixed, and are typically designed to be positioned just above or below the surface of the water. Alternatively an on-demand platform (or multiplatform system) is available with can appear on the surface when the experimenter chooses, controlled by a silent, low voltage, electrically isolated neodymium based controlled HVS actuator system.

In all cases the design of the platform is crucial to ensuring that the animal will be able to climb onto it without slipping. This is important as slipping and scrabbling has the potential to create unwelcome quantitative measurement artifacts.

Measurement & Analysis in Morris Water Maze

Although traditionally the basic measurement has been latency (i.e. time to reach platform), this does not distinguish slower swimming or specific search patterns that are highly diagnostic of different behaviors. Because of this HVS Image developed Video Tracking for Richard Morris and have continued to lead with the most sophisticated, yet easiest to use video tracking systems. Unlike other systems we don’t include measurements and techniques that have been shown not to work or to be unreliable in normal laboratory environments, meaning that you can set up and be working often in minutes rather than days.

Tracking is performed using either a full HVS Image System or HVS Image software on a laboratory PC. Off the shelf webcams may be used but for best results an HVS Image Lab Camera can be specified which can take a variety of CS mount lenses and is available for visible light, infra red or both.