Research feature: Why you don't look at your feet when you walk
Stephen Lomber, PhD, and his team are learning from the walking habits of cats. Using a unique cooling system developed in their lab, they have pinpointed a part of the brain involved in acquiring and maintaining the memory of obstacles in our environment. This memory system allows us to walk through a busy crowd or hike on an uneven trail without having to look down at our feet as we walk.
“You do this unconsciously every day. You don’t usually walk around looking at your feet – you are looking several seconds ahead at where you want to go. So, whether that’s going over a curb, or moving around a puddle, there is a short term memory system that stores the information about what you are about to encounter,” said Stephen Lomber, PhD, professor in the Department of Physiology and Pharmacology and Canada Research Chair in Brain Plasticity and Development.
Similarly, this system allows animals with four legs, like cats, to walk over an object with their front legs, and avoid the same object with their back legs without having to look at the object again.
Based on this knowledge, Lomber and a team of researchers at Western’s renowned Brain & Mind Institute examined what would happen if they turned off the specific areas of a brain believed to be associated with this memory system. By using a focal cooling system, they temporarily deactivated small regions of the brain in the parietal cortex. When a specific region, called 'Area 5', was cooled, the cat no longer remembered the object that it had stepped over with its front legs a moment before.
Furthermore, similar memory deficits were observed with 'Area 5' cooling when the cat either saw the obstacle during the initial approach, or when the forelegs suddenly tripped over an obstacle they did not see previously.
“What this tells us is that this region of the brain is critical for maintaining the working memory of an obstacle acquired through vision or touch that is used to modify stepping for avoidance,” said Carmen Wong, a PhD candidate, and lead author of the study published this month in the journal Cerebral Cortex (doi: 10.1093/cercor/bhx186). “This work helps us understand how the brain can obtain and store information about nearby objects and use it to adapt our movements to our surroundings.”
The researchers point out that as humans, while we don’t have a second pair of legs to worry about for obstacle avoidance, we still rely on our ability to remember obstacles in our surroundings as we walk, so we likely have a similar region of the brain that allows us to do this. They believe this area of the brain may be involved in that disconcerting feeling that you get when walking up the stairs in the dark and attempt to step up onto a stair that isn’t there.
“In this case, perhaps that part of your brain is remembering something in your surroundings when it shouldn’t’ be,” said Wong.