Lithium increases selective attention in rats.

Both 0.15 and 1.50 mEq/kg lithium chloride were found to increase inspective exploration (i.e. behaviors directed at the close examination if discrete stimuli in a new environment) in rats. In addition, 1.50 mEq/kg LiCl decreased general activity, irrespective of the characteristics of the experimental situation. The dose-independent increase in inspective exploration was interpreted as increased selective attention to salient stimuli which provide information about the environment. This hypothesis predicts that both doses of lithium should decrease distractibility by irrelevant stimuli. This prediction was confirmed in a second experiment, in which the ability of a tone to suppress drinking by thirsty rat was reduced by both doses of lithium. A two-factor model of lithium's action in rats is proposed. Lithium produces a dose-independent improvement of selective attention to stimuli which provide detailed information about the environment. In addition, lithium exerts dose-related effects on activity levels: a mild increase in activity with dose in the 0.15-0.20 mEq/kg range and a decrease in activity with doses of 0.50 mEq/kg and higher.