Performance of auditory discrimination in rats lacking the striatopallidal pathway originating from the DLS. Rats (n = 12–16 for each group) were trained for the auditory two-choice reaction time task. After the rats had achieved the 80% criterion, they were given a bilateral injection of IT or PBS into the DLS, and then tested for the task performance. The correct response ratio (A), correct response time (B), and omission ratio (C) in each session are plotted. The values at the pretreatment phase (Pre) are the averages at 3 d before the injection. **p < 0.01, compared with each of the non-Tg/PBS, non-Tg/IT, and Tg/PBS groups; *p < 0.05, compared with the Tg/PBS group, LSD test. Error probability for the stimulus repeated or changed is also given D. The probability was calculated on the basis of the two stimulation patterns. **p < 0.01, compared with each of the other three rat groups, LSD test.