REtinal and VIsual Cortical Response in Early PSYchosis

The severity of psychotic disorders and their disabling potential in young patients represent a major public health problem. These populations are affected by high-level cognitive disorders associated with highly integrative functions. However, there is increasing evidence of lower-level impairments, including vision. Indeed, the literature reports electrophysiological abnormalities at the retinal level, reflected by an alteration of the signal transmission in the retinal ganglion cells (RGC), photoreceptors and bipolar cells. At the cortical level, numerous studies report electrophysiological abnormalities associated with the activity of the primary visual areas. These both electrophysiological measurements have the advantage of being objective, reliable and reproducible, thus leading to new research perspectives concerning the link between retinal and cortical measures in psychosis. These measures could also be interesting for the detection of the risk of conversion to psychosis, before it develops. The transition to a state of psychosis is in fact marked by the appearance of symptoms, which can occur several years before the diagnosis and impact the duration of the untreated psychosis. Thus, the notion of a clinical state at high risk of psychosis (CHRP) defines a population of patients said to be at risk of psychosis. These symptoms precede the occurrence of the first psychotic episode (FEP), indicating the clear transition to psychotic illness. The questions that arise at the present time concerned the early detection and intervention of psychosis during this prodromal phase. This detection could be done via electrophysiological measures associated to the visual processing, but also via measures of neuropsychological evaluations and behavioral measures. That is why, a study on retinal and visual cortical alterations coupled with neuropsychological assessments and behavioral measures in populations at risk of populations at risk of CHRP psychosis and in FEP would potentially reveal predictive biomarkers of the pathology. Such a project could lead to the development of retino-cortical biomarkers in mental health and will eventually lead to to create ultra-portable, reliable and routinely usable measurement devices for the early detection of psychosis in clinic. Main objective: To measure retinal and visual cortical electrophysiological responses in clinical subjects at high risk of psychosis (CHRP) in comparison with first-episode psychotic patients (FEP) and healthy controls (CS) Secondary objective(s) : Compare ERG traces obtained from the "Retinaute" portable ERG device produced by the company BioSerenity with ERG traces obtained from a standard device ERG measurement device "MyPackOne" produced by the company Metrovision among healthy controls To measure performance on neuropsychological tests in clinical subjects at high risk of psychosis (CHRP) compared to patients with a first episode of psychosis (FEP) Measuring temporal prediction in tactile modality (unimodal) with a motor task, in clinical subjects at high risk of psychosis (CHRP) in comparison with first-episode patients (FEP) and healthy controls (CS) Measuring temporal prediction in visual and tactile (multimodal) modalities/Measuring temporal prediction in visual modality (unimodal) with a classical perceptual task in clinical subjects at high risk of psychosis (CHRP) in comparison with patients with a first psychotic episode with a first episode of psychosis (FEP) and healthy controls (CS) To compare the sensitivity of behavioural and EEG measures to the prediction of tactile vs. visual stimuli, and multimodal vs. unimodal