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Solving problems of spatial orientation

Where am I?

(March 9, 2000, Gazette)

Dr. Gerard Martin and one of his subjects.

Photo by Chris Hammond

 

By Andris Petersons
SPARK student

The door is open and I find myself out in the big world. I try to get oriented but in fact I am desperately lost. Nothing reminds me of my previous experience.

I wonder where food is. My favourite toy is somewhere around here. Blue curtain, chairs and a painting on the wall ... I don’t know where I am.

If I am a rat, I do it again and again until hopefully I solve the puzzle and find the food. If I am a child below the age of two, I just wait until I am old enough. If I am an Alzheimer’s patient...

Probably many of us have found it difficult to locate ourselves in places such as MUN. It takes time to learn where buildings are and then add them to our mental map. Dr. Gerard Martin, Psychology, has been working on spatial problems for almost 10 years. His current project is titled Spatial Learning: the Role of Orientation and Geometry.

“My research is curiosity driven,” Dr. Martin said. He is interested in finding out how rats solve spatial problems, how they know where they are and how they use information to make maps.

Dr. Martin’s findings challenged the previous understanding of how animals make maps. Earlier scientists thought that animals were just looking around and using the objects to make their map. According to this if an animal wanted to find food he went directly to the place, for example, under the shelf. It was believed that a disoriented animal without a sense of direction would not have any trouble finding food. Knowing where he was, the animal would always find the food under the shelf.

Dr. Martin carried out an experiment. He disoriented the rats by putting them in metal containers and gently rotating them. What resulted was they were simply unable to find the food, presumably under the shelf. They looked at the environment, the same place, as if they did not know it. Every time they entered the same environment they behaved as if it were for the first time. The rats did not recognize that these were the same chairs, the same shelf, and the same curtains.

A child below the age of two will behave in the same way as the rats if put in a room after being disoriented. The child’s favourite toy is always in front of the blue curtain. If the room is rectangular the child will confuse the two corners – the one with the blue curtain and the opposite. Children below the age of two don’t seem to use the objects to determine the location of the toy. Each time a child enters the room he behaves as if it is happening for the first time.

Dr. Martin speculated that the problem with rats and children might apply to those suffering Alzheimer’s disease. One of the many damaged parts in the brain of an Alzheimer’s patient is the hippocampus, a part responsible for spatial orientation and the creation of cognitive maps. If disoriented rats can’t solve the spatial problems, then they can’t code information to find things where they are. It is possible that if you suffer from Alzheimer’s disease and your hippocampus is damaged, in a sense you are disoriented and one of your problems is that you can’t code the information. It means you don’t know where you are and you are lost.

Disoriented rats can’t find or remember the location of food because they have lost their sense of direction. They can solve other problems that do not require a sense of direction. Alzheimer’s patients have a spatial deficit caused by disorientation. If they can be given a sense of direction, they would be more likely to encode and remember things that happe to them.

Thus, Alzheimer’s patients would probably do better at home where they have orientation. If they are institutionalized, they might get worse.


“Everything that makes it difficult for them to achieve orientation would interfere with encoding of any other information,” Dr. Martin added.

In this project Dr. Martin works closely with his colleagues from the Psychology department, Dr. Carolyn Harley, Dr. John Evans and Dr. Darlene Skinner, and Dr. Dale Corbett from the Faculty of Medicine, as well as graduate students.

This project is funded by NSERC.