Society For Neuroscience, New Orleans, November 2003
Program Number:
271.5 Day /
Time: Sunday, Nov. 9, 1:00 PM - 2:00 PM
FEEDBACK VERSUS ADAPTATION IN THE MOTOR CONTROL SYSTEM: DOES THE BRAIN USE INTERNAL MODELS FOR BIMANUAL COORDINATION AND TIMING?
Amir Karniel, Eldad Klaiman, and Victor Yosef
Department of Electrical Engineering, Technion – Israel Institute of Technology, Haifa 32000, Israel
A prominent yet controversial hypothesis in movement science asserts that the
brain contains internal models of the controlled system. Mechsner et al. (Mechsner F., Kerzel D.,
Knoblich G. & Prinz W. Nature 414, 69-73 2001) have recently reported a
series of ingenious experiments with surprising results about the ability to
perform an otherwise difficult bimanual task with altered visual feedback. They concluded that there is no need for
internal models to explain their results.
We explore an opposite interpretation, in which a new horizon presents itself for movement
science, extending the fruitful field of study in reaching movements adaptation
to the arena of bimanual coordination and timing.
One feature of bimanual coordination tasks is the difficulty of untrained individuals to produce non-harmonic polyrhythms. To study this feature, we have designed two simple variations of Mechsner’s experiment. In the first, subjects are asked to tap with the index fingers on two keys while an altered visual feedback is provided in the form of two rotating discs such that when rotating at equal speeds the subject where able to produce a non-harmonic polyrhythm. The second system consists of two rotating handles below an opaque plate with computerized target/feedback display. This second system was designed to further study bimanual adaptation and it includes passive damping as well as motors to facilitate the generation of various force fields. We have analyzed the performance in an attempt to distinguish between feedback and adaptive control. Further experiments are required in order to better understand the relative role of feedback and adaptation in the context of bimanual coordination.
The straight-line path invariance of reaching movements with the notion of internal models has stimulated a wide range of research with promising scientific and medical applications. Introducing the notion of internal models to the study of bimanual adaptation based on the symmetry invariance calls for various experiments in different transformations to determine the structure and limitations of the internal representations.
Theme: D1a/b Motor systems, Kinematics, reaching, finger
Keywords:
MOTOR LEARNING, RHYTHM, SENSORIMOTOR, CENTRAL PATTERN
GENERATOR..