Long-term effects of LSD-25 on easy and hard visual discrimination in rats

Rats subjected either to unilateral frontal cortex lesion or sham operation were trained to discriminate between a lighted and unlit alley to escape to shock. After reaching criterion, the rats were intubated with either placebo or LSD-25 (1.0 mg/kg). One week or 1 month later they were given discrimination trials with either an increased (hard) level of task difficulty, or with the same (easy) level used in pre-intubation training. A single-dose effect, as long as 1 month post-intubation, was observed both in error scores and running time, but only with hard discriminations. The study emphasizes the sensitivity of the experimental paradigm which reduces the risk of Type II error.