Disturbed sense of limb-ownership is due to lesion of the right posterior insula

Hemiparetic stroke patients with disturbed awareness for their motor weakness, i.e. who show anosognosia for hemiparesis/-plegia (AHP), may exhibit further, abnormal attitudes towards and/or perceptions of the paretic/plegic limb. We investigated a series of 79 consecutively admitted acute stroke patients with right brain damage and hemiparesis/-plegia and found a tight association between AHP and such abnormal feelings. Ninty-two percent of the patients with AHP showed a 'disturbed sensation of ownership' (DSO) for the paretic/plegic limb in addition. The patients had the feeling that their contralesional limb(s) do not belong to their body or even belong to another person. Analysis of lesion location contrasting these patients with a group of right brain damaged control patients without AHP and DSO revealed that the right posterior insula is a crucial structure involved in these phenomena. Together with the recent observation in healthy subjects that the right posterior insula plays a significant role in self-attribution of actions, the present findings point to a new understanding of the role of the right posterior insula. It seems to be a crucial structure involved in the genesis of our sense of limb ownership and to self-awareness to one's belief about limb movement.