Taste-to-postingestive consequence conditioning: is the rise in sham feeding with repeated experience a learning phenomenon?

Although the progressive increase in intake with repeated sham feeding experience is assumed to reflect the extinction of learned satiety, the involvement of associative learning in this phenomenon has never been directly demonstrated. We show that: a) animals attenuate sham feeding on initial exposure only with foods tasting like those they have fed normally before, and b) latent inhibition, which retards the formation of CS-US associations in classical conditioning preparations, prevents the association of a taste with its postingestive consequences. These data suggest both that learning plays a role in the development of sham feeding and that associative linking of a food's taste with its postingestive consequences occurs during ingestion. The present results identify properties of taste-to-postingestive consequence conditioning and indicate how the sham feeding preparation can be used to identify the physiological events mediating this learning.