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Background: Virtual Reality is an interactive three-dimensional computer generated environment. Providing a complex and multi-modal environment, VR can be particularly useful for the study of complex cognitive functions and brain disorders. Here we used a VR world to measure the distortion in reality perception in schizophrenia patients., Methods: 43 schizophrenia patients and 29 healthy controls navigated in a VR environment and were asked to detect incoherencies, such as a cat barking or a tree with red leaves., Results: Whereas the healthy participants reliably detected incoherencies in the virtual experience, 88% of the patients failed in this task. The patients group had specific difficulty in the detection of audio-visual incoherencies; this was significantly correlated with the hallucinations score of the PANSS., Conclusions: By measuring the distortion in reality perception in schizophrenia patients, we demonstrated that Virtual Reality can serve as a powerful experimental tool to study complex cognitive processes.

Our goal is to develop a new family of automatic tools for the diagnosis of schizophrenia, using Virtual Reality Technology (VRT). VRT is specifically suitable for this purpose, because it allows for multi-modal stimulation in a complex setup, and the simultaneous measurement of multiple parameters. In this work we studied sensory integration within working memory, in a navigation task through a VR maze. Along the way subjects pass through multiple rooms that include three doors each, only one of which can be used to legally exit the room. Specifically, each door is characterized by three features (color, shape and sound), and only one combination of features -- as determined by a transient opening rule -- is legal. The opening rule changes over time. Subjects must learn the rule and use it for successful navigation throughout the maze. 39 schizophrenic patients and 21 healthy controls participated in this study. Upon completion, each subject was assigned a performance profile, including various error scores, response time, navigation ability and strategy. We developed a classification procedure based on the subjects' performance profile, which correctly predicted 85% of the schizophrenic patients (and all the controls). We observed that a number of parameters showed significant correlation with standard diagnosis scores (PANSS), suggesting the potential use of our measurements for future diagnosis of schizophrenia. On the other hand, our patients did not show unusual repetition of response despite stimulus cessation (called perseveration in classical studies of schizophrenia), which is usually considered a robust marker of the disease. Interestingly, this deficit only appeared in our study when subjects did not receive proper explanation of the task.