Oscillatory correlates of visuomotor control under varying amount of feedback delay
A weighted integration of visual and proprioceptive movement feedback is key for an adaptive body representation by the brain. Previous work has suggested a relationship between alpha and beta oscillations in sensory cortices and inter-sensory attentional control under visuo-proprioceptive incongruence compared with congruence; and frontal theta oscillations as a marker of the related cognitive-attentional control and response inhibition. Here, we asked whether these oscillatory correlates indicate a gradual adjustment of attention and the corresponding sensory weights, rather than merely a response to conflict per se. Thus, we adopted a recently developed virtual reality based hand-target phase matching task: Participants had to track a target oscillation with recurrent grasping movements of a virtual hand, which they controlled via a data glove. We added a small or a large delay to the virtual hands movements, introducing varying amounts of visuo-proprioceptive conflict. Concurrent EEG recordings revealed a delay-dependent modulation of (i) sensorimotor beta oscillations, (ii) oscillations "entrained" at key movement frequencies over central-parietal sensors, and (iii) mid-frontal theta oscillations. Granger causality analysis suggested that entrained oscillations were more strongly predictive of visual kinematic signals, whereas the prediction of somatosensory kinematics was attenuated depending on the amount of delay. Finally, phase-amplitude couplings suggested that sensorimotor beta coupled with the movement-related oscillations as well as mid-frontal theta. Our results thus establish key oscillatory correlates that scale with the amount of visuo-proprioceptive conflict during visually guided action.