Impaired visuomotor adaptation in Parkinson disease during a computer-mediated aiming task
Résumé
Aiming requires the transformation of visual information concerning target locations into motor commands to allow the hand to move toward the targets. Additional sensorimotor transformations are necessary if a tool such as a computer mouse is used and/or if the movement is not directly seen, but monitored on a computer screen. The aim of this study was to determine the effect of using a display requiring additional sensorimotor transformations on aiming behavior of PD patients. Ten PD in the ON state (63.63±6.99 years) and 10 age-matched healthy participants (63.22±7.17 years) performed aiming movements toward three targets in 2 conditions: direct visual feedback where the starting base, the hand and the target were readily available, and indirect feedback where visual information (target, mouse-cursor and starting base) were displayed on a computer screen. For both groups, reaction times were shorter and movement times were longer in the indirect feedback condition compared to the direct feedback condition. PD undershot the target significantly more than control participants and their movements were less straight and less smooth during computer-mediated aiming than during direct aiming. Overall, these results indicate that, even though time parameters were affected by the condition for all participants, movement execution was less efficient during computer-mediated aiming for PD only, suggesting that PD are affected by the supplementary sensorimotor transformation required during computer-mediated aiming. These abnormalities appear not to be corrected by dopaminergic therapy. These findings may have consequences for some day-today living activities such as using computers or driving. P3.106 Dendritic cell vaccine against human a-synuclein aggregates Background: Immunization therapies for neurodegenerative diseases were initially focused on clearing extracellular deposits of abnormal proteins typified by b amyloid of Alzheimer's disease. Immunization of mice with full-length human a-synuclein (a-syn) has been reported to result in high relative affinity antibodies