Body representations and basic symptoms in schizophrenia.

Patients with schizophrenia report a wide range of anomalous body experiences. According to the basic symptom model of schizophrenia, disturbances of body perception and awareness are among the most powerful predictors of the changes in the subjective experience of the self in schizophrenia. In this study we first investigated the body structural representation (BSR), a specific aspect of body awareness, and its association to basic symptoms in patients with schizophrenia. Using a finger localization task, we found that patients are significantly less accurate than healthy controls when asked to identify pairs of fingers touched by the experimenter, when the hand is hidden from view. Most importantly, patients' performance at the finger localization task was negatively associated to basic symptoms: the worse the individual accuracy, the higher the SPI-A total score. Moreover, the accuracy at the finger localization task was also negatively correlated with the malleability of the sense of body ownership: the less the individual ability to localize fingers, the stronger the rubber hand illusion. These results are in agreement with the idea that self-disorders in schizophrenia reveal a disconnectedness that can be regarded as a problem of disembodiment and traced back to abnormal body experiences.