Effects of synthetic Delta(9)-tetrahydrocannabinol on binocular depth inversion of natural and artificial objects in man

Binocular depth inversion represents an illusion of visual perception that is sensitive to various behavioural and psychiatric conditions. It is affec ted by cannabinoids, reflecting associated changes in perception. The prese nt study investigated the differences in binocular depth inversion of diffe rent classes of natural and artificial objects and the effect of synthetic Delta(9)-tetrahydrocannabinol (Dronabinol) on these illusionary perceptions . Using this model, the effects of orally administered Dronabinol on binocu lar depth inversion were investigated in 17 healthy male volunteers. Pictur es from natural and artificial objects were presented stereoscopically and the depth perception of the volunteers was scored in an operationalized way . The timecourse of the effects of Dronabinol on binocular depth inversion was analyzed with regard to the stimulus classes (natural and synthetic obj ects). Significant differences in binocular depth inversion of the differen t groups of stimuli were revealed. Objects with a higher degree of everyday familiarity were generally seen as more illusionary than those with a lowe r degree of everyday familiarity. A strong impairment of binocular depth in version due to Dronabinol was found in most classes of objects. Analysis of different stimulus classes provides further information on the underlying perceptual processing of binocular depth inversion. An impairment of top-do wn processing of visual sensory data by Dronabinol is suggested. The ananda midergic system seems to be involved in areas of visual information process ing.