As I mentioned in my last post, I am working with two different cohorts of rats. The first group of rats was introduced to the lab a few months ago and I have already completed multiple stages of the experiment with them: the Water Maze, Habituation, Linear Track, and currently the W-maze Alternation task. The second group of rats was just introduced to the lab last week which is why they recieved health checks.
This week, the second group of rats completed the Water Maze. The Water Maze lasts a week, and is crucial in testing the rats’ cognitive abilities, visual acuity, and motor skills. This test decides the yoked pairs (one young and one old rat). Yoked pairs are used because even though the research is focused on the interaction between the hippocampus and PFC, the research is also looking at the changes in the brain that occur through the aging process, so we pair a young rat and old rat with similar performance. Lastly, the Water Maze can also be used to assess if a rat is blind. If we find a rat to be blind, we cannot use the specific rat for the upcoming experiments.
The first few days of the water maze test spatial memory. The platform is set at a single location for these first few days. We put a paint in the pool that makes the water opaque so the platform is hidden. Around the pool of water are visual cues in hopes that the rats will take mental note of where the platform is, so that with each trial when the rat is dunked into the pool at a different insertion point, they can find the platform in a shorter amount of time. The time it takes to find the platform is recorded for each trial. Following these few days of testing spatial memory is a day of testing visual acuity. Instead of keeping the platform in a set place and hidden, the platform is visible and changes location for each trial. This solely tests whether the rats can find the platform with their eyes.
This is a digital sketch of the Water Maze I found online:
Between each trial the rats are held in temperature-controlled case. They all cozy together to keep warm. I took a picture of them because it was so cute.
Unfortunalty after completing the last trial of the water maze, one of rats was very weak and sick looking. We noticed his eyes were struggling to keep open and the color was changing from red to pale pink. His head began rocking and his body could not maintain balance. After trying to keep him stable and warm, we were told he probably had a brain tumor because of how he was behaving (these rats also get tumors often). He had to be put down. I was very sad to see him go because he was so cute and sweet (not to sound weird but I grow attached to these rats). Anyways, his brain is now in the fridge for us to examine or dissect if we wish (silver lining?!).