Multisensory remission of somatoparaphrenic delusion: My hand is back!

Abstract

This study investigates whether the rubber hand illusion (RHI) can induce a remission of somatoparaphrenia, a somatic delusion usually following right-hemisphere damage, which typically manifests as a defective sense of ownership of one's contralesional body parts. First, we show that patients with somatoparaphrenia can experience a reliable RHI, exhibiting illusory effects similar to those reported by healthy participants. Moreover, synchronous touches applied to the patients' visible disowned left hand (rather than to the rubber hand), and to their right invisible unimpaired hand, induce an immediate self-attribution of the disowned hand, without affecting other sensorimotor or attentional disorders. The higher-level representation of the body concerned with ownership, deranged as a somatic delusion in patients with somatoparaphrenia, is penetrable, and can be restored by multisensory stimulations.

Figures

CT images Figure 1. (A) P1. (B) P2.

Setups for the RHI and for the multisensory stimulation of the left disowned hand Figure 2. (A) Rubber hand illusion (RHI). (B) Multisensory stimulation of the left disowned hand. (C) Questionnaire results: The questionnaire included the 9 statements shown. Asterisks = statements featuring the RHI. Error bars = SE for controls.