The effects of scopolamine on a two-cue discrimination

Rats were trained with a tone, light or a tone–-light combination as the discriminative stimulus. These groups were tested after doses of scopolamine and it was found that groups trained with a single cue were more sensitive to the drug than double-cue groups, although their pre-drug responding was similar. A similar pattern was found among individuals in the double-cue groups in which there was a significant correlation between dependency on a single cue, as shown in transfer tests, and drug sensitivity. These results were interpreted in terms of scopolamine-induced changes in stimulus sensitivity produced by a modification of the neural mechanisms controlling attention.