Deficits in processing of sensory context associated with schizophrenia. (360G-Wellcome-088219_Z_09_Z)

Although schizophrenia affects more than 500,000 people in the UK, its neural basis remains poorly understood. What is increasingly clear is that the diverse range of symptoms associated with the disorder are linked by a pervasive problem with the appropriate processing of context. We have reported that people with schizophrenia are largely immune to a visual illusion that relies on suppressive contextual interactions (contrast gain control). The first series of experiments examine contrast gain control in schizophrenia in some depth. We will modify an established combined fMRI-psychophysics paradigm to (a) measure Threshold-versus-Contrast (TvC) functions and so determine if reduced inhibition confers better detection performance in the test group and (b) relate this to the BOLD contrast response function in test and control groups. The second series of psychophysical experiments will determine if gain control deficits extend into domains other than contrast, such orientation and moti on-direction. Finally we will use fMRI and psychophysics to investigate gain-control in another sensory modality: tactile perception. These findings will contribute both to understanding sensory abnormalities associated with schizophrenia and, we hope, in the potential to diagnose it, using psychophysical and fMRI measures.