Grant: Research Tools and Instruments - Category 1 (<$150,000)

One of the most interesting (and difficult) problems the brain faces in controlling parts of the body such as the arm has to do with compensating for changes in the mechanics and dynamics of motion - both short term changes that arise when we manipulate objects, and long-term effects due to changes in the size and shape of our own bodies. One of the main theoretical concepts that has been proposed to explain this flexibility in motor control is that the brain uses central representations or "internal models" of limb dynamics to achieve this compensation. However, little is known about how the brain establishes these internal models or how they are adapted over the course of motor learning. This proposal requests funds to purchase a custom-made state-of-the-art robotic device specifically designed to alter the mechanical and dynamical behavior of the human limb during reaching movements by applying precise, computer-controlled loads to the shoulder and elbow joints independently. This new device will allow limb dynamics to be experimentally manipulated in specific ways, so that the mechanisms underlying the formation and adaptation of internal models by the motor system may be studied directly. The KINARM device (Kinesiological Instrument for Normal and Altered Reaching Movements) is a robotic exoskeleton that attaches to a subject's arm using custom-fitted fibreglass cuffs. High performance computer-controlled torque motors are used to apply precise position- or velocity-dependent loads to the shoulder and/or elbow joint during movement. Motor encoders measure the kinematics (positions and velocities) of joint motion and standard link-segment modelling techniques are used to calculate the net muscular torque at each joint.