Dietary gluten and learning to attend to redundant stimuli in rats

The purpose of the present study was to assess the effect of a high-gluten diet against a gluten-free diet on learning stimulus-response relationships in rats. In the first phase of training rats learned to associate a stimulus light with responding on a particular response lever. In the second phase, the same rats were exposed to new, but redundant stimuli to guide responding (a tone and houselight). Probe trials, involving only new stimuli, revealed that rats fed a gluten-free diet displayed a "blocking" effect. That is, gluten-free rats did not learn to associate these new stimuli with particular responses. In contrast, high-gluten rats very quickly learned to use these redundant stimuli to guide responding. Subsequent phases of training demonstrated, however, that this group difference could be removed. The present findings are discussed in the context of the possible links between dietary gluten and schizophrenia.