Expectations affect the contribution of tonic global inhibition, but not of phasic global inhibition to motor imagery.

In motor imagery, effector-specific inhibition (inhibition of the used effector) and global inhibition (inhibition of all motor commands) prevent actual actions. Global inhibition is partly maintained over time (tonic global inhibition) and partly implemented in response to certain events (phasic global inhibition). We investigated whether expectations about the action mode (imagination or execution) of upcoming actions affect the contribution of tonic and phasic global inhibition to motor imagery. Using the action mode switching paradigm, participants switched between imagined and executed hand movements. In Experiment 1, we manipulated the relative frequency of imagined and executed actions. Tonic global inhibition was more pronounced with high imagination frequency, indicating that it is subject to expectation effects. When tonic global inhibition was higher, phasic global inhibition and effector-specific inhibition were lower, indicating that different forms of inhibition complement each other. In Experiment 2, we manipulated the predictability of the action mode of the next action (predictable vs. random). Phasic global inhibition was not influenced by predictability, indicating that it is rather not subject to expectation effects. In conclusion, tonic but not phasic global inhibition is modulated by expectations regarding upcoming actions. The interplay between different forms of inhibition in motor imagery is context-dependent. (PsycInfo Database Record (c) 2021 APA, all rights reserved).