Multisensory integration in schizophrenia: A behavioural and event-related potential study

Introduction. Successful processing of multisensory stimuli increases the likelihood of detection or identification of salient, biologically significant events faster and more efficiently than unisensory inputs. Schizophrenia (SZ) patients show deficits in unisensory processing, but it is unclear whether impairments are seen to multisensory stimuli, a process known as multisensory integration (MSI). We used behavioural and event-related potential (ERP) measures to examine MSI in SZ and healthy controls (HC). Methods. Thirty-three SZ and 30 HC completed a target detection task with unisensory and multisensory stimuli. Reaction times (RT) were measured while their electro-encephalogram (EEG) was recorded. Two auditory (N100 and P200) and visual (P100 and N160) ERPs were examined. MSI was analysed in terms of violations of RT to the race model and by comparing ERPs in the MSI condition to the sum of the unisensory ERPs. Results. Both groups showed faster RT in MSI compared to unisensory conditions. SZ had non-significantly fewer violations of the race model compared to HC. SZ had significantly smaller amplitudes to unisensory visual N160 and auditory P100 relative to HC; there were no significant group differences on any ERP measure of MSI. Conclusions. SZ showed relatively intact MSI with subtle (non-significant) differences at the neural and behavioural levels compared to HC. Our results suggest that neural processes associated with MSI are not an additional source of impairment in SZ.