Invention Connects Brain Functioning to Limb Control

Originally Published MDDI October 2002

R&D DIGEST

A neuroscientist at Queen's University (Kingston, ON, Canada) has created a mathematical model and a new device that could eventually increase understanding of the role the brain plays in arm and leg movement. His invention may ultimately improve methods for assessing and rehabilitating stroke and spinal cord victims. It could also help provide the basis for developing neural prostheses capable of restoring function to paralyzed limbs.

The inventor, Stephen Scott, PhD, calls his experimental device the KINARM (kinesiological instrument for normal and altered reaching movement). By combining it with a new mathematical model, the mechanics of limb movement in multijoint motor tasks can be objectively quantified and manipulated for the first time. Scott says the device has already generated several new observations on how the human brain coordinates limb movements.

A forthcoming pilot project at St. Mary's by the Lake Hospital in Kingston will entail use of the device to quantify motor function of stroke patients. Motor patterns will be examined first for a number of simple tasks while subjects maintain fixed arm postures. Subsequent tests will involve more-sophisticated tasks where the subjects learn to make reaching movements while the robot applies complex loads to assess their ability to learn new motor skills. The researcher hopes to identify which tasks patients can and cannot perform, and to create "fingerprints" that can aid in the diagnosis and classification of motor dysfunctions.

Says Scott, "We needed a different experimental paradigm to understand how neurons in the brain are involved in controlling movement. Once you've built the technology, the rest becomes much easier."

Patented in 2000, the KINARM device has hinge joints that are aligned with a person's shoulder and elbow, a configuration that allows horizontal arm movements. A computer projection system provides virtual targets in the plane of the arm. Each joint can be manipulated independently as different loads are added selectively. This enables the system to independently manipulate the mechanics of the shoulder and elbow joints during multijoint tasks.

A KINARM system is in development for the University of Chicago. Says Scott, "We hope to give other researchers an opportunity to use this technology to answer questions about limb movement that couldn't be posed before."

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