Abstract
Whereas cognitive changes across adult lifespan have been intensively studied, sensorimotor changes are not well understood. Saccadic eye movements are extremely well suited to investigate visuomotor control and several studies have explored age-related changes in saccadic control, but plasticity processes have been neglected so far. We were particularly interested in whether the ability of the oculomotor system to compensate for systematic foveal endpoint errors deteriorates with age. We investigated backward saccadic adaptation in 20 young subjects (M=29.3 years, range 21-39 years) and 21 senior subjects (M=68.7 years, range 61-75). Subjects had to make horizontal saccades to targets presented at 12 deg eccentricity. After a baseline we applied a double step paradigm in which the target was displaced to 8 deg eccentricity during the saccade. In the baseline session, we observed, consistent with previous findings, an increase of saccadic latencies with age. Neither accuracy nor precision of saccadic control was affected by age. For the double step trials we examined magnitude and rate of gain adaptation. Young and senior subjects were equivalently able to adapt to sensorimotor discrepancies. We found no difference in plasticity parameters during adaptation. In the post-adaptation session, though, age groups differed significantly in persistent amplitude change relative to the baseline session. Whereas younger subjects still showed an amplitude reduction of 3.8%, amplitude in senior subjects was just reduced by 1.6%. Our results provide evidence of robust oculomotor plasticity across a broad age range. However, more pronounced persistence of amplitude change after adaptation in younger subjects points to age-related differences in consolidation of motor learning.
Meeting abstract presented at VSS 2016