MDMA and memory: the acute and chronic effects of MDMA in pigeons performing under a delayed-matching-to-sample procedure

In pigeons performing a memory task with 0-, 3-, and 6-second delays, MDMA (0.32–5.6 mg/kg) generally reduced accuracy and response rates at doses of 3.2 mg/kg and above. Accuracy was inversely related to delay length without the drug. Tolerance developed after chronic exposure to 3.2 mg/kg, with greater tolerance at the 0-second delay than at longer delays. No behavioral deterioration occurred when the chronic regimen ended, indicating an absence of behavioral dependence. Although MDMA can have neurotoxic effects, it does not inevitably produce long-lasting or cumulative behavioral impairment.

Study at a glance

Abstract

The purpose of the present study was to examine the acute and chronic effects of (+/-)3,4-methylenedioxy-methamphetamine (MDMA) in pigeons responding under a delayed-matching-to-sample procedure with 0-, 3-, and 6-s delays. In the absence of drug, accuracy (percent correct responses) was inversely related to delay length. When administered pre-chronically, MDMA (0.32-5.6 mg/kg) generally decreased accuracy and response rates at doses of 3.2 mg/kg and above. Although humans report a distinct "hangover" when exposure to MDMA ends, performance of pigeons in the present study did not deteriorate when the chronic regimen ended, indicating an absence of behavioral dependence on the drug. Tolerance developed following chronic exposure to 3.2 mg/kg. In general, greater tolerance occurred at the 0-s delay than at longer delays. Although MDMA is reported to have neurotoxic effects, it does not inevitably produce long-lasting or cumulative behavioral impairment.