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Above: Prof. Lauren Sergio with some of her CFI-funded equipment
So you think it’s easy to see an object, reach for it and get it. But did you know that, in order to do that successfully, your brain has to transform a sensory signal into a complex pattern of muscle activity?
The control processes employed by the brain which underlie this seemingly straightforward task are not as yet completely understood, and that is what Professor Lauren Sergio, School of Kinesiology & Health Science, is trying to find out. She is focusing her Canada Foundation for Innovation-funded research particularly on the signals used in the cortical areas of the brain for these sort of arm reaching movements.
More specifically, what Sergio will be measuring is hand-joint motions; forces the hand or joints use to produce either limb motion or force right at the hand; and muscle activity responsible for force generation at the joints. This area of research is termed "motor psychophysics."
Right: side scan of Sergio's head, taken from her Web site
By using transcranial magnetic stimulation Sergio disrupts specific motor cortical regions during what she calls "whole arm motor tasks," so that she can observe the effect on directed movement or force generation.
"This way, I can observe the contribution of different cortical areas to these distinct components of motor output," said Sergio. "The overall goal is to understand which aspects of motor output are reflected in the activity of different cortical areas."
In a second line of research Sergio is studying the central mechanisms involved in the planning and execution of arm movements performed under increasingly arbitrary visuomotor transformations, using CFI-funded eye-and-limb-tracking equipment.
One of Sergio’s projects in this field includes research into the use of functional magnetic resonance imagining. She compares neural activity in different areas of the human brain as people perform increasingly "indirect tasks," such as pointing to a spot on a computer screen versus using a joystick to move a cursor to a spot.
As Sergio explains, "Some of the movements that we make are directly toward certain objects. However, many of the movements we perform require more arbitrary associations, and we do them effortlessly. When we use a computer mouse to move a pointer on a monitor, this skill requires a remapping of motor output from a frontal plane to a horizontal one in the brain.
"In this situation, for example, to displace the pointer upward on the screen requires a forward movement of the hand. This learned transformation between visual presentation and motor production is not innate, and can deteriorate under neuropathological conditions such as Alzheimer’s disease."
Through her research, Sergio hopes to be able to outline what normal hand-eye coordination is. She will then be able to offer a standard against which to measure what is not normal, such as an Alzheimer's patient's attempts to do the same tasks.