November 2, 2007
Feline footsteps point to visual memory
Research demonstrates cats' 'physical memory'
by Ileiren Poon
There's a reason cats rarely make a false step - they remember where their feet have been.
New research by Department of physiology professor Keir Pearson, a leading authority on the neurobiology of locomotion, has demonstrated that felines can remember the location of an obstacle for as long as 10 minutes after encountering it.
Pearson and his research team conducted experiments in which they'd have a cat step over a block with its front feet. Before the cat crossed its hind legs over the obstacle the researchers would interrupt the cat's walk by presenting it with a tasty snack. With the cat distracted, the researchers would remove the obstacle. Up to 10 minutes later, once the cat resumed its walk, it would still move its hind legs over the obstacle, even though the obstacle was no longer there.
"He still thinks it's there. That memory, we know, can last 10 minutes," said Pearson.
The memory may actually last longer, but 10 minutes was the maximum length of time Pearson and his fellow researcher David McVea were able to distract the animals.
"It always works. They never don't do it," said Pearson. "We're asking what are the mechanisms involved in forming this long-lasting memory. One of the thoughts we had was that it involves the front legs stepping over. So, we asked the question, if the front legs don't step over but the cat sees the obstacle, will he still step over?"
The answer is no. If the cat sees the barrier, but doesn't step over it, the memory isn't retained for that length of time. For the first few seconds, the animal will attempt to step over the absent barrier, but the memory is quickly lost.
"It certainly works for a few seconds, but the loss of visual memory happens very, very quickly," said Pearson. "It was surprising to us how short visual memory was. We thought it would last longer than a few seconds. What this tells us is that our body movements themselves can contribute to the establishment of memories."
For example, a person walking through a cluttered room in the dark will do much better if they've already traversed the space at least once, as opposed to having just looked at it.
"I park my car on different levels of the parking lot each day, but I never forget where it is. But, I wonder if somebody took me by wheelchair from my car to my office, would I remember it as well?" he said. "The fact that I've walked down four flights of stairs had provided me with information to solidify that memory - at least for the day."
Pearson's research on the neurobiology of locomotion has included the movement of mice, cockroaches, locusts and humans. He's managed to informally reproduce the results of the high-stepping cats in other quadrupeds - dogs and horses.
"What we really want to know is how we navigate complex environments, especially when we're in motion ourselves," he said, adding that the results have applications in diagnosing problems with human memory. "We're currently trying to develop some tests for patients with Parkinson's disease and AIDS to test the memory functions of these patients."
Pearson's also consulting with Japanese scientists who are trying to create walking robots.
"Now, these guys want to create autonomous, walking robots - in other words, robots that can find their own way around the environment," he said. "These machines are going to have to do what the cat does, they're going to have to re-map the location of objects as they move - they've got to keep track of where those obstacles are."