Latent inhibition improves discriminative fear conditioning in rat model for schizophrenia

Karin Oshima, Shinichi Kumagai, Tomoyo Isoguchi Shiramatsu, Hirokazu Takahashi

Abstract: The aberrant salience hypothesis is a well-known framework that explains symptoms of schizophrenia. However, no studies have directly examined the relationship between this hypothesis and impaired discrimination learning between neutral (CS-) and aversive (CS+) sound stimuli in a rat model of schizophrenia. The present study aimed to examine the relationship between aberrant salience and the discrimination learning deficits in a rat model of schizophrenia. Rats were subjected to classical discriminative fear conditioning which follows latent inhibition to reduce the saliency of CS. Duration of freezing behavior demonstrated that schizophrenia model rats succeeded in the discriminative conditioning. Moreover, the magnitude of auditory evoked response revealed altered tonotopic map in these rats, supporting the successful learning. These results indicate that the decrease in saliency helps discriminative learning of the schizophrenia model rats, supporting that the deficits in discrimination in the schizophrenia can be discussed within the framework of the aberrant salience hypothesis for this disease.