Auditory sensory processing deficits in sensory gating and mismatch negativity-like responses in the social isolation rat model of schizophrenia.

Patients with schizophrenia exhibit disturbances in information processing. These disturbances can be investigated with different paradigms of auditory event related potentials (ERP), such as sensory gating in a double click paradigm (P50 suppression) and the mismatch negativity (MMN) component in an auditory oddball paradigm. The aim of the current study was to test if rats subjected to social isolation, which is believed to induce some changes that mimic features of schizophrenia, displays alterations in sensory gating and MMN-like response. Male Lister-Hooded rats were separated into two groups; one group socially isolated (SI) for 8 weeks and one group housed (GH). Both groups were then tested in a double click sensory gating paradigm and an auditory oddball paradigm (MMN-like) paradigm. It was observed that the SI animals showed reduced sensory gating of the cortical N1 amplitude. Furthermore, the SI animals showed significant reduction in cortical MMN-like response compared with the GH animals. No deficits in sensory gating or MMN-like response were observed in the hippocampus (CA3) of the SI animals compared with GH animals. In conclusion, the change in sensory gating of the N1 amplitude supports previous findings in SI rats and the reduced MMN-like response is similar to the deficits of MMN seen in patients with schizophrenia. Since reduced auditory MMN amplitude is believed to be more selectively associated with schizophrenia than other measures of sensory gating deficits, the current study supports the face validity of the SI reared rat model for schizophrenia.