Gustatory thalamus lesions in the rat: III. Simultaneous contrast and autoshaping.

The performance of rats with electrophysiologically guided electrolytic lesions of the gustatory thalamus (GT) was compared to that of control subjects in two experiments. In Experiment 1, the lesioned rats showed normal simultaneous contrast effects (both positive and negative) during brief, alternating access to 0.15% saccharin and 1.0 M sucrose. There was, however, a substantial lesion-induced impairment in the level of conditioned stimulus-directed maintenance responding on the autoshaping procedure of Experiment 2. These findings are discussed with respect to the anticipatory contrast deficit recently reported in GT-lesioned rats.