EEG and Behavioural Correlates of Virtual Reality Treatment of Environmental Zeitgebers in Schizophrenia and Bipolar Disorder

Patients with bipolar disorders report an acceleration or slowing of time flow, and patients with schizophrenic spectrum disorders a time fragmentation. These disorders would be linked to disorders of the sense of self. Assessing these time-related disorders could help to better predict psychotic conversion in vulnerable subjects. In this protocol, the investigators wish to develop playful methods for the evaluation of alterations in the passage of time, based on the use of virtual reality. The protocol will be tested in stabilized but chronic bipolar or schizophrenic patients, vs. healthy subjects matched on age, sex, and study level. The protocol will include two experimental sessions. It will begin with a waiting room-like session, at the end of which the subject will be asked to retrospectively estimate the time that will have passed. The games that will follow will all be based on the principle of temporal waiting. A first signal will indicate the start of the trial, and a target will be presented at varying times after this first signal. The later the target is presented, the more the subject expects and prepare for the target, and the faster he or she is. This time delay is measured by the subject's response (response time, error rate, eye fixation), but also by electrical signals measured by electroencephalography (EEG). The two experimental sessions will include several temporal manipulations during these tasks, intended to highlight alterations in the time flow in patients compared to controls. In one of the sessions, a starfield will be presented and the speed of the stars in the starfield will be manipulated, as a proxy for the speed of the environment. In one condition, the speed of the object will be average, and in the other the speed will be self-adjusted by the subject. In a control condition, the speed of the object will be zero. In the other experimental session, distractors will be presented during the waiting phase of the target. They will be presented either simultaneously or asynchronously. In one control condition the distractors will be absent. In both sessions it will be examined how the behavioral and EEG cues are affected by the manipulations. A double dissociation is expected, with greater disturbance in patients with bipolar disorder when standard movement is used, whereas patients with schizophrenia should be disturbed mainly when asynchronous distractors are presented.