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Movement regularities and their possible uses as diagnostics tools and as performance indexes of goal-directed movement
Dr. Elizabeth Torres
Thursday, December 03, 2009, 12:00pm - 07:00pm
Rutgers University, Department of Psychology
We humans perform activities of daily living with great flexibility. Although we mostly rely on procedural memories for many daily routines, we are also quite capable of improvising and readily adapting an old motion to a new context as a given new situation may demand. Despite such a variable repertoire of motions, the movements of the highly versatile human arm system manifest various regularities during goal-directed behavior. I have found several of these consistent patterns and uncovered their invariance to systematic changes in the speed of the motion, the starting posture of the arm, the hand path curvature and to changes in a variety of contexts requiring outwardly directed motions to reach and to grasp objects, even in the presence of obstacles.
Because our bodies are compliant with the laws of physics, one could think that such invariants were merely the byproduct of the biomechanics of our bodies and/or of the physical constraints of the world in which we inhabit. Several of these movement invariants however are under cognitive control. They are violated when the brain is injured, yet the spared brain systems can repair them and bring them back to normal levels when provided with the source of sensory guidance most appropriate to the systems that still function.
I will present in this talk recent findings in adult patients and normal controls that illustrate the aforementioned points. Specifically, I will focus on data from Parkinson's patients and a patient with a left parietal lobe lesion in relation to normal controls that demonstrate (1) the default preference of these systems for a particular source of sensory guidance, (2) the use of invariant metrics as indexes of sensory-motor performance, and (3) the possible use of these metrics as diagnostics tools to identify spatio-temporal motion deficits specific to a brain region. In the last part of the talk I will introduce our recent efforts to adapt these measures to study children with developmental disabilities and in particular children diagnosed with autism spectrum disorder.