Touch feel illusion in schizophrenic patients

Background: The rubber hand illusion is a tactile sensation referred to as an alien limb. The illusion has been explained by a spurious reconciliation of visual and tactile inputs reflecting functional connectivity in the brain and was used to explore alterations of functional connectivity in schizophrenia. Methods: The rubber hand illusion was achieved when two paintbrushes simultaneously stroke the hand of the subject hidden from vision by a screen, as well as an artificial hand placed in view of the subject. The rubber hand illusion was assessed with a questionnaire affirming or denying the occurrence of the illusion. Results: Schizophrenic subjects felt the illusion stronger and faster then did normal control subjects. Some rubber hand illusion effects correlated with positive symptoms of schizophrenia but not with negative symptoms. Conclusions: Altered functional integration of environmental inputs could constitute the basis for erroneous interpretations of reality, such as delusions and hallucinations.