Introduction

Introduction

Rats placed in a circular pool readily learn to swim directly toward a small escape platform, submerged just below the surface of the water, from any point in the pool. Morris reported that if rats were trained to find the platform from only a single starting point, then they will still swim straight to it if tested from a new starting position (Morris, 1981). These findings have been widely taken as evidence that rats form a cognitive map of the pool and its surrounding landmarks, which allows them to determine the direct route to the platform from any point in the pool, even if they have never traversed it before. But there are reasons to question this story. Even if they are always placed in the pool at a single start point, on early trials rats will swim around the pool, more or less at random, until they find the platform. They then inevitably learn the route to the platform from virtually any point in the pool by using distant visual cues.

Whishaw (1991) argued that rats do not use single landmarks to navigate toward a submerged platform in the pool, but rather configurations of two or more landmarks. If this holds true, then the unique cues that rats uses to identify the location of the platform are not the individual characteristics of the separate landmarks, but rather of their configurations. Therefore, we hypothesize that by altering the position of five landmarks surrounding the Morris’ water maze will increase the amount of time it takes rats to reach the escape platform.

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April 29, 2009. Uncategorized. Leave a comment.

Method

Method

Participants

The subjects of this study include Sprinkles and Trixie, two female albino rats derived from a Sprague Dawley strain. At the start of testing, the rats were approximately three and a half months old. Both Sprinkles and Trixie were housed in individual cages with water continuously available. Trixie and Sprinkles were fed once a day by the experimenters. Sprinkles receives 13 grams of food a day and Trixie receives 13 grams. Sprinkles’ weight has been 180-200 grams and Trixie has been 190-210 grams.

Materials

The rats will be trained and tested in a Morris Water Maze which will be constructed out of Crystal inflatable pool by Intex to simulate the Morris water maze. The pool diameter is 147.32 cm and has a height of 33.02 cm. To create our hidden platform we purchased a Vinyl Fun Tunnel which is 10.16 cm wide and 27.04 cm high and then glued Plexiglas to both ends on the tunnel. The Plexiglas glued to the bottom of the tunnel is 13.17 x 13.17 cm and the plexiglas at the top of the hidden platform is 10.16 x 10.16 cm.The water in the pool consists of tap water heated to 26 degrees Celsius. The water temperature should be maintained and should not deviate within one degree of 26 degrees Celsius. In order to maintain the temperature of the pool, water should be removed after the trials. The next day right before trials, warm to hot water should be added to achieve the desired temperature. By adding non toxic white paint by Crayola the water in the pool is made opaque. The landmarks used in this study include; Jessica Miller, a researcher in this experiment, a fake water lily with a height of 67.31 cm, a 22.86 cm x 30.48 cm piece of black construction paper with five white 2.54 cm x 22.86 cm horizontal lines, a piece of 22.86 cm x 30.48 cm white construction paper with a 15.24 cm red octagon, and a magazine clipping with a photo of Ed Westwick. The photo has dimensions of 24.765 cm x 17.78 cm. We will record our findings on a digital camera.

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Pool made opaque with white paint and the landmarks in the moved locations.

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Tunnel that served as our platform with Plexiglas top and bottom.

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Landmark

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Landmark

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Landmark

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Landmark

Design and Procedure

The purpose of this study is to determine if rats associate landmarks with the location of a hidden escape platform. To measure this association Sprinkles and Trixie will be trained to complete a Morris water maze, which is a behavioral procedure designed to test spatial memory. The rats will be placed in the water tail first to avoid stress. As stated in Water Maze- Morris Water Maze (1998) stress impairs learning. The pool will contain an escape platform hidden a few(?) millimeters below the surface of the water. Once the rats have been released into the water they will then swim around the area of the pool in search of the hidden escape platform. The escape from the water reinforces the rats to quickly find the platform.

For this experiment there will be four phases. During phase one the escape platform will remain visible, above the water surface while the water remains in its natural state. Four trials will be conducted each day per rat, with each trial alternating the direction from which the rat is placed in the pool. The directions are defined as north, south, east and west. The number of days depends on the individual animal and how quickly they learn an escape platform is present in the pool, Trixie and Sprinkles needed six days to obtain an average time for each direction. The landmarks will be placed in the room in specific locations and will remain in the same location for the first three phases of the experiment. The second phase consists of the escape platform being hidden under the surface of the water in its original location. This is in hopes of removing the platform from the rats’ field of vision, forcing them to rely on the spatial cues of the room to find the escape platform. Four trials will be conducted each day per rat, with each trial alternating the direction from which the rat is placed in the pool. Our rats needed four days to complete this phase of the experiment. Phase three involves changing the color of the water. The water will be made opaque by adding non-toxic white paint. Everything will remain in its original location and the platform will remain hidden below the water surface. The rats will once again enter the pool from all four directions and obtain an average time. For this phase of the experiment Trixie and Sprinkles needed four days to complete all 16 trials. The experimenter will then alter the position of the landmarks from the pool during phase four. When moving the landmarks, each one was rotated two landmark positions counterclockwise with the water opaque and the platform hidden. Both rats will then complete a series of trials over four days to test if the position of the landmarks has any effect on their ability to quickly find the hidden stationary platform. The mean scores from each rat’s trials from previous phases of the experiment will be compared to determine whether or not the landmarks had any effect on their ability to find the platform.


April 28, 2009. Uncategorized. Leave a comment.

Results

Results

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Figure 5. Represents a comparisons of the mean scores during each phase of the experiment for each rat. The graph suggests the rats learned the location of the escape platform.

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April 28, 2009. Uncategorized. Leave a comment.

Results

Results

Our experiment did not provide us with any significant differences between the phases where the platform was visible, where the platform was hidden, and when the landmarks were rotated. We constructed tables and graphs demonstrating the scores from each rat’s performance throughout the experiment. Each rat has a mean score from each direction from each phase of the experiment. Each mean score is comprised of four trials. The four tables below demonstrate the average scores of each rat for each phase of the experiment in seconds.

Table 1. Mean Scores of Trixie’s Performance

Phase 1

Phase 2

Phase 3

Phase 4

South

9.45

7.67

6.99

5.12

North

13.56

10.33

6.63

2.74

East

14.29

6.23

8.04

2.34

West

9.17

7.69

12.48

5.52

Table 2. Mean Scores of Sprinkles’ Performance

Phase 1

Phase 2

Phase 3

Phase 4

South

9.01

7.59

4.74

2.87

North

12.39

9.04

6.95

4.69

East

13.84

2.9

1.44

1.76

West

9.51

5.03

11.26

4.56

Table 3. Mean Scores of Trixie’s Means

Mean Score

Phase 1

11.62

Phase 2

7.98

Phase 3

8.54

Phase 4

3.93

Table 4. Mean Scores of Sprinkles’ Means

Mean Score

Phase 1

11.19

Phase 2

6.14

Phase 3

6.1

Phase 4

3.47

April 28, 2009. Uncategorized. Leave a comment.

Discussion

Discussion

The results obtained from this experiment did not demonstrate the kind of learning we expected, however, we still see behavior worth exploring. Based on past research, going into this experiment we expected to see the rats take longer to find the hidden platform once the landmarks were rotated. If the rats were using the visual landmarks to find their way to the hidden platform, we would observe an increase in the amount of time it took them to find the platform in phases three and four. But we did not notice an increase in either Sprinkles’ or Trixie’s performance. Since we did not see any change in the rat’s performance (in seconds) in how long it took them to get to the platform, we can assume that they were not using the landmarks to find the hidden platform; there was something else at work helping the rats find their way to the platform.

We contemplated what could have caused the rats behaviors. One such reason could be the configuration of the room we used. We were unable to move the door or window in the room. These two served as landmarks without us even trying, however, due to the lack of space we were not able to make an attempt to move the door or window. These two could have served as permanent cues to our rats showing them where the platform was hidden. Furthermore, there were many other cues and landmarks in the room which we could not account for or control, besides the door and window. It is possible the configuration of the room itself told the rats where the platform was hidden. Another reason for their behaviors could be due to the motor skills the rats developed during this experiment. Perhaps they never looked at the landmarks in the room and developed a cognitive map of the pool which helped them get to the platform. Maybe it was the motor skills and the swimming abilities that told the rats where they needed to go. Finally, we considered attributing learning to the rats’ ability to find the platform without using the landmarks as cues. The rats performed 48 trials before the landmarks were moved; they were probably able to learn where they needed to swim without looking around. While we did change the location from which the rats entered the water (north, south, east, or west) Sprinkles and Trixie probably knew where they needed to swim to from each of those directions.

If we were to conduct this experiment again, we have numerous changes that we would make in our methods in hopes of running a more effective study looking at the rats’ use of visual landmarks. One of the biggest flaws in our experiment was having the rats perform so many trials before the landmarks were moved. If we only obtained a baseline score for each direction for each rat, they would not have been so aware of where the platform was located. The amount of trials they performed in trials one, two, and three contributed to their learning of where the platform was located before we even attempted to move the landmarks. These landmarks were no longer cuing them to where the platform was located as we had hoped; conducting fewer trials would hopefully give the rats less of a chance to develop the skills to know where the escape platform is located. We would also try and conduct the experiment in a bigger room where we could actually rotate the entire pool, therefore also moving the door and window which served as landmarks by accident. In addition to the limited space available for conducting this experiment we were also very limited on our resources and materials. Having a bigger room and perhaps even a bigger pool could possibly help us obtain more accurate results demonstrating whether or not rats use spatial cues to help them navigate.

Our results have implications for further research in the area of visual cues in rats. If the rats are able to find the escape platform without referencing landmarks, what is telling them where the platform is located? There must be something else at work directing the rats in the specific direction. Since the rats were placed into the pool from four different directions, they had to have the cognitive abilities to tell them where to go from each direction. Our hypothesis was that the visual cues and landmarks would direct the rats to the hidden platform but we were proven wrong by Sprinkles and Trixie. Further research is needed in this area to determine how rats are able to get to a specific location containing a goal, whether the goal is food or escape from a dangerous situation.

April 28, 2009. Uncategorized. 1 comment.

References

References

Morris, R. G. M. (1981). Spatial localization does not require the presence of local cues. Learning and Motivation, 12, 239-261.

Morris, Richard G.M. (2008). Morris Water Maze. Retrieved February 23, 2009, from http://www.scholarpedia.org/article/Morris_water_maze.

Morris R (1984). Developments of a water-maze procedure for studying spatial learning in the rat. Journal of Neuroscience Methods 11.1: 47–60

Water Maze – Morris Water Maze (1998). Retrieved February 23, 2009, from http://www.watermaze.org/.

Whishaw, I. Q. (1991). Latent learning in a swimming pool place task by rats: Evidence for the use of associative and not cognitive mapping processes. Quarterly Journal of Experimental Psychology, 43B, 83-103.

April 28, 2009. Uncategorized. Leave a comment.

Moving into Phase Three!

This week we moved on to phase three of our experiment, which was where we kept the landmarks the same, hid the platform under the water, and made the water opaque. We were able to use nontoxic white paint to make the water opaque; however, it is not as white as we would have liked it to get. We use 113.4 grams of Crayola nontoxic white paint (a whole container!) and we were afraid if we kept adding more and more paint there would come a point where it would no longer be making a difference. We also needed to be realistic and realize it would be too expensive to be adding more than one container per session.

When the rats were first placed in the water for this phase, their times were higher than they had been in phases one and two. Like mentioned in our previous post, Sprinkles is the rat that appears to swim with her head higher above the water’s surface we see this again contributing to her performance in the water. In phase 3, she took longer to find the hidden platform than she did in phases 1 and 2, however, Sprinkles was the faster of the 2 rats in this phase. We contribute Sprinkles’ faster times to the observation that she seems to swim with her head higher than Trixie.

We have a few more days of phase 3 to complete, after that we will move on to phase 4, our final phase where the landmarks will be rotated.

Here is a video of Trixie’s’ performance during phase three:

And this is Sprinkles’ performance, as you can see she is swimming right around the platform and does not climb on top of it the first time she approaches the platform.  This causes us to think she can not see the platform since the water has been made opaque.

Comparison of performances:

These times are from the last day in each phase, the trial in each direction except for phase 3 which is incomplete so the most recent times are given. The times are given in seconds.

Sprinkles

Direction

Phase 1

Phase 2

Phase 3

North

1.93

10.13

5.93

South

5.65

2.79

3.84

East

.89

3.49

1.39

West

12.22

3.49

3.77

Trixie

Direction

Phase 1

Phase 2

Phase 3

North

1.92

6.00

10.47

South

6.49

2.16

4.33

East

1.10

1.32

1.50

West

5.90

3.91

9.29

April 12, 2009. Uncategorized. Leave a comment.

Phase Two of Water Maze Experimentation

This past week we were able to finish running our phase one trials along with completing the second phase of our experiment. The second phase is where we hid the platform by keeping the water level above the platform and kept the water its natural color while the landmarks remained the same. We continued to alternate the directions from which the rat was being placed in the water (north, south, east, or west) and ran trials for 4 days, 4 trials per day per rat. So for phase two, each rat has a total of 16 trials from the 4 different directions.

Just by looking at the performance times we noticed on the first day of phase two the rats did take a little big longer on the first trial to find the platform. However, after the first trial their times went back down to where they had been during the initial training, phase one. The experimenter who is in the room while the rats perform, Jess is able to notice more details about their behavior while they complete the trials than the experimenter who is not in the room, Ashley. Jess has observed the rats swimming with their heads higher and more above the water in phase two than in phase one. We are now wondering if we can attribute this behavior change to the change in the platform’s visibility from the water. Our question is are the rats are looking around and becoming more aware of their surroundings in an attempt to locate the platform that they can no longer see? This is an important part of our research that we hope will be discovered in the last two phases.

Here is Sprinkles’ performance during phase two. This clip shows her swimming right past the platform at first.

This video shows Trixie’s performance during phase two.

For this next week we plan to begin phase three, where we need to opaque the water, keep the platform below the water surface, and keep the landmarks in the same location.  We are having a little bit of difficulty trying to figure out how to opaque the water.  So far we have tried using baby powder and baking soda, they both did not work. We are going to test out nontoxic white paint and see how that works out!

April 5, 2009. Uncategorized. Leave a comment.

Updated Method Section

Do rats associate landmarks with the location of the hidden escape platform?

Method

Participants

The subjects of this study include Sprinkles and Trixie, two female albino rats derived from a Sprague Dawley strain. At the start of testing, the rats were approximately three and a half months old. Both Sprinkles and Trixie were housed in individual cages with water continuously available. Trixie and Sprinkles were fed once a day by the experimenters. Sprinkles receives 13 grams of food a day and Trixie receives 13 grams. Sprinkles’ weight has been 180-200 grams and Trixie has been 190-210 grams.

Materials

The rats will be trained and tested in a Morris Water Maze which will be constructed out of Crystal inflatable pool by Intex to simulate the Morris water maze. The pool diameter is 147.32 cm and has a height of 33.02 cm. To create our hidden platform we purchased a Vinyl Fun Tunnel which is 10.16 cm wide and ________ cm high and then glued Plexiglas to both ends on the tunnel. The Plexiglas glued to the bottom of the tunnel is 13.17 x 13.17 cm and the plexiglas at the top of the hidden platform is 10.16 x 10.16 cm.

The water in the pool consists of tap water heated to 26 degrees Celsius. The water temperature should be maintained and should not deviate within one degree of 26 degrees Celsius. In order to maintain the temperature of the pool, water should be removed after the trials. The next day right before trials, warm to hot water should be added to achieve the desired temperature. By adding non toxic white paint by Crayola the water in the pool is made opaque. The landmarks used in this study include; Jessica Miller, a researcher in this experiment, a fake water lily with a height of 67.31 cm, a 22.86 cm x 30.48 cm piece of black construction paper with five white 2.54 cm x 22.86 cm horizontal lines, a piece of 22.86 cm x 30.48 cm white construction paper with a 15.24 cm red octagon, and a magazine clipping with a photo of Ed Westwick. The photo has dimensions of 24.765 cm x 17.78 cm. We will record our findings on a digital camera.

Design and Procedure

The purpose of this study is to determine if rats associate landmarks with the location of a hidden escape platform. To measure this association Sprinkles and Trixie will be trained to complete a Morris water maze, which is a behavioral procedure designed to test spatial memory. The rats will be placed in the water tail first to avoid stress. As stated in Water Maze- Morris Water Maze(1998) stress impairs learning. The pool will contain an escape platform hidden a few(?) millimeters below the surface of the water. Once the rats have been released into the water they will then swim around the area of the pool in search of the hidden escape platform. The escape from the water reinforces the rats to quickly find the platform.

For this experiment there will be four phases. During phase one the escape platform will remain visible, above the water surface while the water remains in its natural state. Four trials will be conducted each day per rat, with each trial alternating the direction from which the rat is placed in the pool. The directions are defined as north, south, east and west. The number of days depends on the individual animal and how quickly they learn an escape platform is present in the pool, Trixie and Sprinkles needed six days to obtain an average time for each direction. The landmarks will be placed in the room in specific locations and will remain in the same location for the first three phases of the experiment.

The second phase consists of the escape platform being hidden under the surface of the water in its original location. This is in hopes of removing the platform from the rats’ field of vision, forcing them to rely on the spatial cues of the room to find the escape platform. Four trials will be conducted each day per rat, with each trial alternating the direction from which the rat is placed in the pool. Our rats needed ________days to complete this phase of the experiment.

Phase three involves changing the color of the water. The water will be made opaque by adding non-toxic white paint. Everything will remain in its original location and the platform will remain hidden below the water surface. The rats will once again enter the pool from all four directions and obtain an average time.

The experimenter will then alter the position and distance of the landmarks from the pool during phase four. Both rats will then complete a series of trials over numerous days to test if the position of the landmarks has any effect on their ability to quickly find the hidden stationary platform. The mean scores from each rat’s trials from previous phases of the experiment will be compared to determine whether or not the landmarks had any effect on their ability to quickly find the platform.

References

Morris, Richard G.M. (2008). Morris Water Maze. Retrieved February 23, 2009, from http://www.scholarpedia.org/article/Morris_water_maze.

Morris R (1984). Developments of a water-maze procedure for studying spatial learning in the rat. Journal of Neuroscience Methods 11.1: 47–60.

Water Maze – Morris Water Maze (1998). Retrieved February 23, 2009, fromhttp://www.watermaze.org/.

March 29, 2009. Uncategorized. Leave a comment.

Week two: SUCCESS!

This week was a far more successful week for our group; we were able to really begin our experiment. The transition to our new pool went smoothly, the platform dried to the bottom of the pool and we were then able to fill it with water. We were still having a hard time attempting to maintain the proper water temperature, so we have come to accept the fact that we are going to have to take out cold water and add hot water every day before we begin our trials. It has become easier to do this since the group has developed a method to change the water.

However, despite the difficulties we are experiencing with the water, we are very happy to have had such a successful, productive week with our rats. Each rat performs 4 trials each day with about a 2 to 3 minute break in between each trial. While one rat is swimming, the other is resting and warming up in one of the aquariums. The rats are placed in the water at different starting points for 2 of the trials, each day we rotate the location from which the rat begins swimming. For example on day 1 both rats began trials 1 and 2 from the south end of the pool and for trials 3 and 4 the west end. On day 2, for trials 1 and 2 they began from the east end and for trials 3 and 4 they began from the north end. This pattern continued for the rest of the trials. Both rats receive 13 grams of food per day which is given to them after we run the trials. Sprinkles’ weight has been about 180-200 grams and Trixie has been about 190-210 grams.

We are still working on phase 1 of the experiment, where the platform is not hidden and the water is not made opaque. We will continue on to the next phase when the rats have average times for getting onto the platform. Right now neither rat has an average time for reaching the platform from any starting point, their times have a distinct range. During the trials, we have noticed that both rats are struggling to get up on top of the platform; it almost looks like they are slipping off. From what we have observed, the rat will swim around the pool, find the platform, try and get on but not make it. The rat will then swim away, turn back around and swim straight to the platform and then make it to the top of the platform. Our group has thought perhaps the rats need a powerful swimming start to make it up on top since the platform is above the surface of the water. We tried drying off the platform in between trials but that does not seem to make much of a difference. However, with repeated trials we see a decrease in this behavior in both rats.   They are still taking a longer amount of time to find the platform on the first trial when it is a new entrance, but after the first trial they are no longer finding the platform, leaving and then swimming up to the platform again, they are able to get on the platform on the first approach.  Additionally, we believe that once we move onto the next phase of the experiment, where the platform is below the water level, the rats will not have a problem getting on it because it will be below them, not above them. If this continues to be a problem, we will look into putting some sort of grip tape on top of the Plexiglas platform.

Sample Data from phase 1

Time in seconds

T = trial

South End Entrance:

Trixie: Day One T1:12.08 T2: 12.70 Day Three T1:19.49 T2: 3.56

Sprinkles: Day One T1: 1.08.66 T2: 1.40.07 Day Three T1: 27.10 T2: 3.00

North End Entrance:

Trixie: Day Two T3: 20.60 T4: 16.41

Sprinkles: Day Two T3: 14.60 T4: 3.96

Here is a video of Trixie’s performance during phase 1:

And a video of Sprinkles’ performance during phase 1:

March 24, 2009. Uncategorized. Leave a comment.

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