MRC Guidelines for Good Clinical Practice in Clinical Trials

Voluntary movements are usually preceded by a slow, negative-going brain signal over motor areas, the so-called readiness potential (RP). To date, the exact nature and causal role of the RP in movement preparation have remained heavily debated. Although the RP is influenced by several motorical and cognitive factors, it has remained unclear whether people can learn to exert mental control over their RP, for example by deliberately suppressing it. If people were able to initiate spontaneous movements without eliciting an RP, this would challenge the idea that the RP is a necessary stage of the causal chain leading up to a voluntary movement. We tested the ability of participants to control the magnitude of their RP in a neurofeedback experiment. Participants performed self-initiated movements and after every movement they were provided with immediate feedback about the magnitude of their RP. They were asked to find a strategy to perform voluntary movements such that the RPs were as small as possible. We found no evidence that participants were able to to willfully modulate or suppress their RPs while still eliciting voluntary movements. This suggests that the RP might be an involuntary component of voluntary action over which people cannot exert conscious control. Significance statement The readiness potential (RP), a brain signal that precedes spontaneous, voluntary movements, has been a matter of controversial research for several decades. There has been a long debate on the nature of this signal and the degree to which it undermines the control a person has over their behavior. Thus, assessing the degree to which people are able to exert control over this brain signal is of vital importance. We addressed this question in a neurofeedback experiment. Our results show that people are unable to willfully suppress their RPs, even when explicitly trying to do so. This suggests that the RP is an involuntary and irrevocable component of voluntary action over which people have no control.