Distinct modulations in sensorimotor postmovement and foreperiod β-band activities related to error salience processing and sensorimotor adaptation

Abstract

In a recent study, Tan et al. (2014a,b) showed that the increase in β -power typically observed after a movement above sensorimotor regions (_-rebound) is attenuated when movement-execution errors are induced by visual perturbations. Moreover, akin to sensorimotor adaptation, the effect depended on the context in which the errors are experienced. Thus the β -rebound attenuation might relate to neural processes involved in trial-to-trial adaptive mechanisms. In two EEG experiments with human participants, along with the β -rebound, we examine β -activity during the preparation of reaches immediately following perturbed movements. In the first experiment, we show that both foreperiod and postmovement β -activities are parametrically modulated by the sizes of kinematic errors produced by unpredictable mechanical perturbations (force field) independent of their on-line corrections. In the second experiment, we contrast two types of reach errors: movement-execution errors that trigger trial-to-trial adaptive mechanisms and goal errors that do not elicit sensorimotor adaptation. Movement-execution errors were induced by mechanical or visual perturbations, whereas goal errors were caused by unexpected displacements of the target at movement initiation. Interestingly, foreperiod and postmovement β -activities exhibit contrasting patterns, pointing to important functional differences of their underlying neuronal activity. While both types of reach errors attenuate the postmovement β -rebound, only the kinematic errors that trigger trial-to-trial motor-command updates influenced β -activity during the foreperiod. These findings suggest that the error-related modulation of the β -rebound may reflect salience processing, independent of sensorimotor adaptation. In contrast, modulations in the foreperiod β -power might relate to the motorcommand adjustments activated after movement-execution errors are experienced.