There is evidence suggesting that the oculomotor system has privileged access to the neural processes driving hand movements. While the nature of this privileged access is an interesting object of study in its own right, this research will seek to exploit it in order to deepen our understanding of the processes of motor learning. That is, eye movements will be used to indicate the subjects' expectations regarding the results of their hand movements, thus allowing a disassociation between motor performance and intention. In order to allow the eye movements to be used in this way, it will be necessary to separate effects of visual and proprioceptive feedback from those reflecting control signals (i.e., efferent copy). This can be done by application of computational models, for example Kalman filters, and through manipulation of visual and proprioceptive feedback. Our preliminary results show that in such conditions, eye movements appear to measurably reflect efferent copy of motor commands to the arm. These preliminary results will be fleshed out and expanded, as the success of the project depends on developing a paradigm in which effects of learning of arm movements can be reliably demonstrated movements of the eyes. Once such a paradigm is developed, research will focus on the time course of motor learning. Previous work in the laboratory shows that motor learning involves developing both a forward model (for predicting behavior of the hand and performing feedback control) and an inverse model (used for open-loop control). However, an open and important question is how these two models influence each other and to what degree they are learned simultaneously or sequentially. In order to resolve this question, we will use eye-movements as a proxy to indicate adaptation of the forward model of arm movements.
| Donchin, Opher; Francis, Joseph T; Shadmehr, Reza (2003) Quantifying generalization from trial-by-trial behavior of adaptive systems that learn with basis functions: theory and experiments in human motor control. J Neurosci 23:9032-45 |
| Criscimagna-Hemminger, Sarah E; Donchin, Opher; Gazzaniga, Michael S et al. (2003) Learned dynamics of reaching movements generalize from dominant to nondominant arm. J Neurophysiol 89:168-76 |
