Delta-9-tetrahydrocannabinol impairs visual recognition memory but not discrimination learning in rhesus monkeys.
The effects of orally administered delta-9-tetrahydrocannabinol (THC) were evaluated on two different learning abilities in monkeys. Visual recognition memory, known to depend on limbic system integrity, was tested by means of delayed nonmatching-to-sample and found to be significantly impaired by acute administration of 2 and 4 mg/kg THC given 1 or 2 h prior to testing. Performance was significantly impaired throughout a 21-day period of repeated administration of 4 mg/kg THC and also during a 3-5 day period that began 7-10 days after the last dose of THC. By contrast, 24-h concurrent discrimination learning, a task that monkeys with limbic lesions can perform normally, was not impaired by THC, even following doses as high as 16 mg/kg. These results suggest that THC interferes with recognition memory more than discrimination learning, possibly reflecting a selective action of THC on limbic mechanisms.
Aigner
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Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, MD 20892.
D000284:Administration, Oral; D000818:Animals; D004193:Discrimination Learning / Q000187:drug effects*; D013759:Dronabinol / Q000494:pharmacology*; D008253:Macaca mulatta; D008297:Male; D008568:Memory / Q000187:drug effects*; D014796:Visual Perception / Q000187:drug effects*
D013759:Dronabinol