UC San Diego

Brattleboro rats, a Long Evans strain with a single gene mutation in vasopressin, have inherent cognitive deficits in memory, emotional reactivity, motivation, attention, and social recognition, which are abnormalities associated with schizophrenia. Latent inhibition (LI) refers to a decrease in conditioned learning that occurs when the subject being tested is preexposed to the to-be- conditioned stimulus without the paired unconditioned stimulus. The LI deficit in schizophrenics has been used as evidence of a selective attention deficit in schizophrenia. Given that the Brattleboro rats display several natural deficits that are also seen in schizophrenics, this experiment investigated whether Brattleboro rats also display deficient LI. We hypothesized that the Brattleboro rats will exhibit LI deficits compared to Long Evans rats. The conditioned taste aversion paradigm was used to test LI. Analysis of the data showed that both the Long Evans and Brattleboro rats displayed LI (p<0.05), however, the Brattleboro rats showed reduced LI compared to the Long Evans rats (p< 0.05). Also, we studied extinction of the conditioned stimulus and found the preexposed Long Evans rats extinguished it at a similar rate as the non-preexposed Long Evans rats (p>0.05). However, the preexposed Brattleboro rats extinguished it significantly slower than the non-preexposed Brattleboro rats (p<0.01); they inhibited extinction. Although the Brattleboro rats displayed LI, they will continue to serve as models for schizophrenia because of the other cognitive deficits observed in them