Effects of toluene administration on delayed matching-to-sample performance in the pigeon

Four pigeons were trained using a delayed matching-to-sample task. This task was composed of identity matching-to-sample trials and oddity from sample trials. In the case of identity trials, pigeons were required to choose the same stimulus as a sample to reach a food reward, and in the case of oddity trials, they had to choose a different stimulus from a sample to gain a food reward. After the performance became stable, toluene was administered intramuscularly at dosages of 10, 20, 40, and 80 mg/kg and tests were executed. The dosage of 10 mg/kg toluene caused increases in the percentage of correct responses in the 5- and 10-sec delay intervals, and 20 and 40 mg/kg toluene injections also increased the correct responses to some extent. At the dosage of 80 mg/kg toluene, the correct responses decreased and the performance was impaired. Toluene administration at relatively low dosages, especially 10 mg/kg, seemed to have excitatory effects on the CNS in pigeons, and presumably its arousal actions activated memory processes.