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Séminaire impromptu - Mark LatashControlled Stability of Motor Actions

Abstract :


 When people move, they organize large, redundant (actually, abundant!) sets of elements (limbs, joints, digits, muscles, motor units, etc.) in a task–specific way.
Such organizations have to ensure movement stability, which is crucial for successful actions given that external forces always vary.
The physical approach to this problem has been developed using two theoretical frameworks. One of them is the equilibrium-point hypothesis and its current version – the referent configuration (RC) hypothesis. The other is the idea of intention-specific (task-specific) stability of redundant systems developed within the uncontrolled manifold (UCM) hypothesis. I will describe a theory incorporating both the RC and UCM hypotheses and the idea of hierarchical control. Further, I will present results of several recent experimental studies inspired by this line of thinking.

These studies used perturbations of ongoing movements, analysis of variance across repetitive trials, and analysis of motor equivalence to explore action stability. In particular, I plan to focus on the reactions of abundant systems to transient perturbations and phenomena of equifinality and its violations in abundant systems. These reactions involve novel phenomena such as unintentional movements happening without subject’s awareness.

Selected publications

Latash M.L. (2012) Fundamentals of Motor Control. Academic Press: New York, NY.

 Martin J.R., Latash M.L., Zatsiorsky V.M. (2012) Effects of the index finger position and force production on the flexor digitorum superficialis moment arms at the metacarpophalangeal joints – a magnetic resonance imaging study. Clinical Biomechanics 27: 453-459.

 SKM V., Zhang W., Zatsiorsky V.M., Latash M.L. (2012) Age effects on rotational hand action. Human Movement Science 31: 502-518.

 Park J., Wu Y.-H., Lewis M.M., Huang X., Latash M.L. (2012) Changes in multi-finger interaction and coordination in Parkinson’s disease. Journal of Neurophysiology (in press); doi:10.1152/jn.00043.2012

Scientific focus :

My field of interest is motor control defined as an area of natural science exploring how the nervous system interacts with other body parts and the environment to produce purposeful, coordinated actions. In particular, I have been involved in the development of the equilibrium-point hypothesis and uncontrolled manifold hypothesis using experimental studies of motor coordination during standing, stepping, reaching, and multi-digit (pressing and prehensile) tasks. I have also been interested in changes in motor control and coordination with healthy aging, atypical development, practice, and a range of neurological disorders.