Morris Water Maze Protocol Notes

Overview

Prep guide for conducting the Morris Water Maze with rats over five days. Emphasizes hippocampal-dependent spatial learning, roles, procedures, measures, and facility rules.

Spatial Navigation and Memory

• Spatial navigation: learning relationships among environmental landmarks and self-location.
• Declarative memory supports describing and demonstrating routes and locations.
• Hippocampus is necessary for forming spatial maps and retrieving routes.
• Place/time cell activity underlies navigating real and imagined spaces.

Morris Water Maze: Core Concepts

• Circular pool with opaque water; hidden platform not visible to the rat.
• Rats use distal visual cues on walls and experimenter positions to orient.
• Goal: over trials, rats swim directly to the platform from varied start points.
• Probe trial removes platform to assess memory for platform location.

Dependent and Independent Measures

• Dependent 1: Latency to find the platform (max 60 s per swim).
• Dependent 2: Swim path type (direct beeline vs. circuitous/random).
• Independent: Rat strain (Long-Evans vs. Sprague-Dawley) potential learning differences.

Hippocampus and Lesion Evidence

• Intact hippocampus: rapid, direct paths after training.
• Cortical lesion: similar learning to intact after training.
• Hippocampal lesion: slow, circuitous paths; platform found by chance.

Experimental Roles and Room Setup

• Four experimenters: handler, drawer/latency recorder, timer, pool cleaner (“poop getter”).
• Stand back in room corners; minimize visibility as cues to rats.
• Maze orientation: North at far wall; South near experimenters; West left; East right.

Protocol and Procedure

• Enter facility: scan outer door, close, scan inner door, enter ID code, follow green path.
• Don PPE: gloves, paper gown, booties; then stay on blue “clean” side to testing area.
• Start positions vary across trials: N, S, E, W; platform fixed in upper-left quadrant (between N and W).
• Handler places rat facing pool wall; release gently with hand submerged.
• Timer starts at release; drawer traces path and marks latency reported quietly by timer.
• If no platform in 60 s: handler guides rat to platform; timer holds 10 s; remove to cage.
• Pool cleaner removes bedding/poop between rats.

Training Schedule and Probe Day

• Days 1–4: Four trials per rat per day; all animals complete Trial 1 before Trial 2, etc.
• Day 5 (Probe): One 60 s trial per rat; platform removed; all start South.
• Successful learning shown by concentrated swimming in former platform quadrant.

Data Recording

• One sheet per animal per day with four trial diagrams.
• Drawer notes animal number, day, trial, start location, drawn path, and latency.
• Odd-numbered rats: tail mark; even-numbered: no mark.

Strain Differences: Expectations

• Long-Evans (hooded): more chill; often learn faster; robust for learning/memory.
• Sprague-Dawley (albino): smart and trainable; may be more anxious; possibly slower.
• Task is easy; differences may be small but observable.

Safety, Conduct, and Cleanup

• Quiet environment: indoor voices, no phones; minimize being a visual cue.
• Allergies: inform instructors; follow all rules and positions.
• Bites unlikely; if bitten, flush with water; mothers with pups bite more (not in this task).
• Clean “leave no trace”: sweep debris around cages and pool; dispose of waste.
• Legal logbook: record animal numbers, initials, and “Morris Water Maze” activity.

Key Terms & Definitions

• Declarative memory: memory for facts/events; can be described verbally.
• Spatial navigation: learning and using relationships among landmarks to move.
• Latency: time from release to platform (seconds); max 60 s.
• Probe trial: test without platform to assess memory of platform location.
• Place cells: hippocampal neurons active at specific locations.
• Social cognitive map: hippocampal representation of others by affiliation and power.

Structured Task Summary

Action Items / Next Steps

• Review role assignments and practice quiet positioning in corners.
• Prepare data sheets and timers; confirm platform quadrant and start orders.
• Adhere to 60 s max per trial and 10 s platform hold protocol.
• Log all sessions in the facility book with animal numbers and initials.
• After sessions, complete thorough cleanup and proper sign-out.