Neural correlates of referential/persecutory delusions in schizophrenia: examination using fMRI and a virtual reality underground travel paradigm

Background The brain functional correlates of delusions have been relatively little studied. However, a virtual reality paradigm simulating travel on the London Underground has been found to evoke referential ideation in both healthy subjects and patients with schizophrenia, making brain activations in response to such experiences potentially identifiable. Method Ninety patients with schizophrenia/schizoaffective disorder and 28 healthy controls underwent functional magnetic resonance imaging while they viewed virtual reality versions of full and empty Barcelona Metro carriages. Results Compared to the empty condition, viewing the full carriage was associated with activations in the visual cortex, the cuneus and precuneus/posterior cingulate cortex, the inferior parietal cortex, the angular gyrus and parts of the middle and superior temporal cortex including the temporoparietal junction bilaterally. There were no significant differences in activation between groups. Nor were there activations associated with referentiality or presence of delusions generally in the patient group. However, patients with persecutory delusions showed a cluster of reduced activation compared to those without delusions in a region in the right temporal/occipital cortex. Conclusions Performance of the metro task is associated with a widespread pattern of activations, which does not distinguish schizophrenic patients and controls, or show an association with referentiality or delusions in general. However, the finding of a cluster of reduced activation close to the right temporoparietal junction in patients with persecutory delusions specifically is of potential interest, as this region is believed to play a role in social cognition.