Tetrodotoxin inactivation of the gustatory cortex disrupts the effect of the N-methyl-D-aspartate antagonist ketamine on latent inhibition of conditioned taste aversion in rats

The effect of the non-competitive N-methyl-D-aspartate (NMDA) receptor antagonist ketamine on latent inhibition of taste aversion learning was studied in rats. Systemic injections of ketamine (50 mg/kg) applied after each of three preexposures to sodium saccharin (0.1%) disrupted the latent inhibition effect. The blockade was not due to aversive properties of ketamine, because three saccharin-ketamine pairings did not produce saccharin aversion. Moreover, the ketamine-induced blockade of latent inhibition was disrupted by tetrodotoxin injections (10 ng/mu l)-induced reversible inactivation of gustatory cortex, applied after each preexposure. A specific gustatory cortex mediation of the ketamine effect is discussed. (C) 1998 Elsevier Science Ireland Ltd.