| The broad aim of this research is to understand the neural mechanisms underlying arm movement planning and execution performed under increasingly complex visuomotor transformations. We also wish to characterize the effects of Mild Cognitive Impairment on complex eye-hand coordination.;We observed a progressive decrement in task performance as the spatial location of the required motor output was increasingly dissociated from the spatial location of the guiding visual information for both groups; however, there were significant differences between the two groups in their performance.;Similar to our findings with the Alzheimer's disease patients, these data suggest that visuomotor integration involving the processing of rule based information can be affected even in individuals at a very early stage of cognitive decline, and demonstrate that this type of task represents a sensitive means of characterizing functional motor deficits in cognitively declined populations.;Previously, we have shown that the performance of early-stage Alzheimer's disease patients declined significantly as a visually-guided movement went from having a standard mapping (vision and action spatially aligned) to having a nonstandard mapping (vision and action not spatially aligned). The present study extends this line of research by comparing the accuracy, timing, and error rate of individuals affected by mild cognitive impairment (MCI) to healthy, age-matched individuals performing increasingly dissociated, or nonstandard, visually guided reaching movements. The participants made sliding finger movements over a clear touch sensitive screen placed in two separate spatial planes (vertical and horizontal), to either constantly present or remembered visual targets. These conditions were repeated with the direction of curser motion rotated 180° from the direction of reach movements. We also tested an "arbitrary" condition in which arbitrary symbols instructed the participants to move their hand in certain directions on the touch screen. |
