problems of spatial orientation
9, 2000, Gazette)
Dr. Gerard Martin and one of
by Chris Hammond
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.
wonder where food is. My favourite toy is somewhere around here.
Blue curtain, chairs and a painting on the wall ... I dont
know where I am.
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 Alzheimers
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
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.
Martins 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.
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.
child below the age of two will behave in the same way as the
rats if put in a room after being disoriented. The childs
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 dont 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.
Martin speculated that the problem with rats and children might
apply to those suffering Alzheimers disease. One of the
many damaged parts in the brain of an Alzheimers patient
is the hippocampus, a part responsible for spatial orientation
and the creation of cognitive maps. If disoriented rats cant
solve the spatial problems, then they cant code information
to find things where they are. It is possible that if you suffer
from Alzheimers disease and your hippocampus is damaged,
in a sense you are disoriented and one of your problems is that
you cant code the information. It means you dont
know where you are and you are lost.
rats cant 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. Alzheimers
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.
Alzheimers patients would probably do better at home where
they have orientation. If they are institutionalized, they might
Everything that makes it difficult for them to achieve
orientation would interfere with encoding of any other information,
Dr. Martin added.
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.
project is funded by NSERC.