For most healthy young people, the motion of point-to-point reaching seems simple: starting from point A, you move your arm to take it to point B. But many systems are involved in making this transition, and lots of things can and do go wrong.
Denise Henriques, professor of kinesiology and health science at York University’s Vision: Science to Applications (VISTA) program, uses point-to-point reaching as a model to understand more complex movements.
In her tests, people need to engage multiple senses – such as vision, touch, and body position – and all of these need to coordinate to steer multiple body parts. Her findings have big implications for how environments and technology should be designed.
“In my research, usually we have people try to move a cursor that represents our hand onto different targets,” says Henriques. “So we have a target, they have to move their hand toward it to acquire that target. This involves multiple processes: they have to be able to assess where that target is, be able to figure out where that location is, and figure out the correct movement toward it.”
These computer-based behavioural experiments track and record changes in eye, head and limb movements. From here, Henriques manipulates the test to see how people can respond and adapt to new circumstances, like blocking the visual feedback of being able to see their hand.
“How quickly, how long they’re able to persist in this, whether we see changes in these processes across different populations,” adds Henriques. “I’m interested in seeing how these processes change with age or in patients who suffer from disease or damage.”
In particular, Henriques is interested in the impact of damage to the cerebellum and basal ganglia: areas of the brain that are associated with motor deficits, especially in older people and patients with Parkinson’s disease. These changes in the brain contribute to deficits in motor control and motor learning.
Because vision is a major player in guiding point-to-point movement, changing our environment can make it more accessible.
“We could have better systems for aging people who might have difficulties navigating in this world, in this very complex visual world, and streamline the kind of visual information they need to know when driving, when walking, when reaching, when interacting with objects in their kitchen,” says Henriques.
Accessible design also makes environments easier to navigate and less error-prone for all people, creating safer and more user-friendly roads, community spaces, and experiences for everyone. And that sounds like a meaningful upgrade to stumbling from point A to point B.
