Effects of lithium on appetitive discrimination in the rat

1. The present study attempted to test the hypothesis that lithium (as chloride, 0.15 mEq/kg) promotes an attentional focus onto stimulation of high salience (Cappeliez and Moore 1988). 2. The effect of lithium treatment was studied within the context of discrimination learning in a Y-maze. 3. When the brightness cue (illuminated/dark goal arm) signalled reinforcement (food) and the spatial cue (right/left location of goal arm) acted as a distractor, lithium-treated rats showed evidence of increased readiness to focus onto the brightness cue. 4. When these experimental conditions were reversed in a second experiment, with the brightness cue now acting as a distractor, the performance of the lithium-treated rats was adversely affected. 5. These results are interpreted as supporting the hypothesis that, under the influence of this dose of lithium, rats are more likely to maintain their attention on stimulation of high salience, with accompanying reduction in the processing of peripheral stimulation. The implications of this theory for the understanding of lithium's action and manic-depressive conditions are discussed.