Modulating human sense of agency with non-invasive brain stimulation

Human voluntary actions are accompanied by a distinctive subjective experience termed “sense of agency”. We performed three experiments using transcranial direct current stimulation (tDCS) to modulate brain circuits involved in control of action, while measuring stimulation-induced changes in one implicit measure of sense of agency, namely the perceived temporal relationship between a voluntary action and tone triggered by the action. Participants perceived such tones as shifted towards the action that caused them, relative to baseline conditions with tones but no actions. Actions that caused tones were perceived as shifted towards the tone, relative to baseline actions without tones. This 'intentional binding' was diminished by anodal stimulation of the left parietal cortex [targeting the angular gyrus (AG)], and, to a lesser extent, by stimulation targeting the left dorsolateral prefrontal cortex (DLPFC), (Experiment 1). Cathodal AG stimulation had no effect (Experiment 2). Experiment 3 replicated the effect of left anodal AG stimulation for actions made with either the left or the right hand, and showed no effect of right anodal AG stimulation. The angular gyrus has been identified as a key area for explicit agency judgements in previous neuroimaging and lesion studies. Our study provides new causal evidence that the left angular gyrus plays a key role in the perceptual experience of agency.