NEURAL CORRELATES OF ADAPTATION TO VISUO-MOTOR DELAYS

摘要

When exposed to sensorimotor visual delays people soon learn to control the cursor to intercept a target. This suggests that adaptation to delays in an interception task strongly depends on the coordination of the motor action with the visual information of the delayed cursor. Often people do not generalize to other tasks (de la Malla et al. 2014) implying that proprioception is not temporally realigned with vision. We explore the neural basis of this adaptation by building on the idea that oscillatory coupling between visual and somatosensory areas underpins the interaction between them and should be observed in baselines conditions. We hypothesize that this synchronization will be reduced after adaptation if realignment does not happen. In order to test this hypothesis we measured EEG (32 channels) while subjects performed an interception task. The behavioral experiment was divided in 4 phases: full vision (FV), no vision (NV), adaptation (A), and NV. In the adaptation phase, we incrementally increased (1msec/trial) the temporal difference between the hand and the cursor movements. In the analysis we further divided the adaptation phase in early adaptation (EA) and late adaptation (LA). Since the feedback of the experiment was visual, we focused the analysis on the alpha band (8-12 Hz). Under FV, all subjects (irrespective of the adaptation strength) presented a synchronic activity between occipital and centro-lateral electrodes. However, the synchronization changed depending on the level adaptation to the visual delay. Participants with good adaptation presented less synchronization at EA than FV, and no synchronization at LA. The synchronization remained after adaptation for participants with little adaptation. These results suggest that adaptation to visuomotor delays does not require strong interactions between visual an proprioceptive areas and would be consistent with an absence of temporal realignment between these areas.