The Temporal Stability of Visuomotor Adaptation Generalization

Movement adaptation in response to systematic motor perturbations exhibits distinct spatial and temporal properties. These characteristics are typically studied in isolation, leaving the interaction largely unknown. Here, we examined how the temporal decay of visuomotor adaptation influences the spatial generalization of the motor recalibration. First, we quantified the extent adaptation decayed over time. Subjects reached to a peripheral target and a rotation was applied to the visual feedback of the unseen motion. The retention of this adaptation over different delays (0 to 120 seconds) (1) decreased by 29.0 ± 6.8% at the longest delay, and (2) was represented by a simple exponential, with a time constant of 22.5 ± 5.6 seconds. Based on this relationship we simulated how the spatial generalization of adaptation would change with delay. To test this directly, we trained additional subjects with the same perturbation and assessed transfer to 19 different locations (spaced 15 degrees apart, symmetric around the trained location) and examined three delays (approximately 4, 12 and 25 sec). Consistent with the simulation, we found that generalization around the trained direction (± 15 degrees) significantly decreased with delay and distance, while locations > 60 degrees displayed near constant spatiotemporal transfer. Intermediate distances (30 and 45 degrees) showed a difference in transfer across space, but this amount was approximately constant across time. Interestingly, the decay at the trained direction was faster than that based purely on time suggesting that the spatial transfer of adaptation is modified by concurrent passive (time-dependent) and active (movement-dependent) processes.

from #ORL-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2vktNeH