Feeling touches in someone else's hand.

Cerebral damage may induce a delusional belief so that patients claim that their limbs contralateral to the side of the lesion belong to someone else (somatoparaphrenia). This disorder, which is not due to a general delirium, is frequently accompanied by the inability to feel tactile sensations in the 'non-belonging' part of the body. We report the unique case of a patient with somatoparaphrenia in whom dense tactile imperception in the left hand dramatically recovered when she was instructed to report touches delivered to her niece's hand, rather than to her own hand. We suggest that, through this verbal instruction, the mismatch between the patient's belief about the ownership of her left hand and her ability to perceive touch on it was transiently recomposed. This is evidence that apparently elementary deficits, such as hemianesthesia, and selective delusional behavior, such as somatoparaphrenia, may both originate from an impairment of the body image.