Different effects of nabilone and cannabidiol on binocular depth inversionin man

The physiological and pathophysiological roles of the central nervous endog enous cannabinoid system are not completely understood, but still represent a challenge in basic neurobiological, cognitive, and psychiatric research. The system has been implicated in the pathogenesis of schizophrenia. Binoc ular depth inversion, an illusion of visual perception, provides a model of impaired perception during psychotic states. Using this model the effects of nabilone, a psychoactive synthetic 9-trans-keto-cannabinoid, and of cann abidiol, the main natural component of herbal cannabis, and a combined appl ication of both substances on binocular depth inversion and behavioural sta tes were investigated in nine healthy male volunteers. The time course of t he effects of both substances on binocular depth inversion was analysed aft er oral administration using three different groups of natural stimuli. A s ignificant impairment of binocular depth perception was found when nabilone was administered, but combined application with cannabidiol revealed somew hat reduced effects on binocular depth inversion. The influence of psychoac tive cannabinoids on this perceptual model and the role of the endogenous c annabinoid system in visual information processing are discussed. (C) 2000 Elsevier Science Inc.