Delta 9-tetrahydrocannabinol: elevation of absolute visual thresholds of rabbits.

The effect of Delta 9-tetrahydrocannabinol (THC) on the ability of rabbits to detect a minimal light stimulus (absolute visual threshold) was examined using the method of limits with an aversive classical conditioning paradigm. Both of two dosage levels of THC, similar to an amount ingested by a human from a single cigarette, significantly elevated the absolute visual threshold of all animals. Normal baseline thresholds, however, returned with 24 hours.