An fMRI study of Agency

Angeliki Charalampaki

Abstract

Sense of Agency comprises the experience of authorship over voluntarily executed movements. Research related to this phenomenon is substantial, considering altered Sense of Agency has been linked with neurological disorders like Cerebral palsy, Apraxia and Anosognosia for hemiplegia. Previous studies have pinpointed primarily Anterior Insula and Parietal cortex as two brain loci related with the experience of Sense of Agency or the lack of it respectively. Additionally, it has recently been reported that the coupling between Inferior Parietal Cortex and right Medio-Frontal / supplementary Motor area has a distinct directionality, depending on the stage of the volitional movement. In this study, we were interested in assessing the neuronal mechanism underlying this phenomenon. We therefore performed an fMRI study of Agency, to exploit the high spatial resolution this imaging technique displays. For the purposes of our study twenty participants were recruited. The experimental procedure we considered appropriate to study the Sense of Agency, involved participants laying inside the fMRI scanner and while they had no visual feedback of their hand, they were instructed to draw straight lines on a tablet with a digital pen. They could only see the consequences of their movement as a cursor’s movement on a screen. After finishing their movement, participants were requested to make a judgment over whether they felt they were the Agent of the observed movement or not. The analysis of our data revealed increased activity over left Precentral Gyrus, left Precuneus, left Postcentral Gyrus, right Anterior Cingulate Gyrus and both left and right Midcingulate Gyrus, for the conditions when participants reported themselves as the Agent of the movement, compared to the conditions when they reported lack of Sense of Agency. We analyzed our data in the light of the Comparator Model, which states that Sense of Agency arises only when there is congruence between the predicted Sensory Outcome and the Sensory outcome that accompanies the movement execution. We further argue that it requires more time to make Agency judgments for larger discrepancies between predicted and actual state and that significantly more frequent absence of SoA is reported for those conditions. Even though our results did not allow us to perform a connectivity study over the activated areas, they revealed activity on areas probably related with the experience of Sense of Agency and highlighted the necessity to further study this notion.
OriginalsprogEngelsk
Publikationsdato5 sep. 2017
Antal sider76
StatusUdgivet - 5 sep. 2017

Emneord

  • Sundhedsvidenskab
  • agency
  • fMRI
  • comparator model

Citationsformater