Nicotine enhances acquisition of a T-maze visual discrimination: assessment of individual differences

In the present report, rats' performance was assessed in five tasks designe d to measure behavioral response to different novel stimuli under different experimental situations. Daily nicotine treatment (0, 0.3 or 1.0 mg/kg) be gan after the conclusion of the behavioral tasks and continued throughout t he experiment. Training of a T-maze visual discrimination task commenced af ter 11 days of nicotine pretreatment. As a group, rats treated with the hig her dose of nicotine (1.0 mg/kg) made fewer errors to acquire the initial T -maze discrimination than saline-treated controls. Activity induced by an i nescapable novel environment (i.e. first behavioral screen) was positively correlated with the number of errors to acquire the initial discrimination in the T-maze for the two nicotine-treated groups (0.3 and 1.0 mg/kg). To e xamine this positive correlation further, a median split analysis was condu cted on the novelty-induced activity for each group. Nicotine, especially t he high dose (1.0 mg/kg), enhanced performance in rats that were less activ e in the inescapable novel environment. Nicotine treatment did not affect t he performance of rats that were more active in that environment. After the initial visual discrimination was acquired, the reverse discrimination was trained. Nicotine treatment did not affect performance; the number of erro rs to acquire the reversal for nicotine- and saline-treated rats did not di ffer. Overall a nicotine-induced improvement in performance is demonstrated which can be predicted by a rat's reactivity to environmental novelty. (C) 2000 Lippincott Williams & Wilkins.