Assessing the Validity of an Animal Model of Deficient Sensorimotor Gating in Schizophrenic Patients

Psychiatric researchers need specific animal models to better understand the neurobiology of schizophrenia. Prepulse inhibition (PPI), the reduction in startle produced by a prepulse stimulus, is diminished in schizophrenic patients. Theoretically, deficient PPI in schizophrenic patients reflects a loss of sensorimotor gating that may lead to sensory flooding and cognitive fragmentation. In rats, PPI is disrupted by systemic administration of dopamine agonists or by manipulations of neural circuitry linking the limbic cortex, striatum, pallidum, and pontine reticular formation. This loss of PPI in rats may be a useful model for studying the neurobiology of impaired sensorimotor gating in schizophrenic patients. We assessed the face, predictive, and construct validity of this animal model. Face validity was supported: stimulus manipulations produced parallel changes in PPI in humans and rats, and the dopamine agonist apomorphine disrupted PPI in rats, mimicking PPI deficits in schizophrenics. Predictive validity was supported: the ability of antipsychotics to restore PPI in apomorphine-treated rats correlated with clinical antipsychotic potency (r_s=.991) and D₂-receptor affinity (r_s=.893). Antipsychotics that restore PPI in apomorphine-treated rats include "typical" antipsychotics and the "atypical" antipsychotic clozapine. Construct validity was supported: PPI was disrupted in rats when dopamine was infused into the nucleus accumbens; this effect was blocked by haloperidol. The loss of PPI in dopamine-activated rats may be a valid animal model of sensorimotor gating deficits in schizophrenic patients. This model may help us understand the neurobiology of cognitive deficits in schizophrenic patients.