Yhe use of Cannabis sativa by humans dates back several thosand years, for boths its psychotomimetic and potential medicinal properties. As scientific research methods developed, the cannabinoids present in this herb were characterized, as well as their complex interface with the human central nervous system, provided by the activation of specific receptors. The subsequent descrption if an endogenous cannabinoid system in the mammalian brain shifted the notion of cannabis as a recertional drug to a therepeutic alternative for psychiatric disorders. However, the neuroanatomical sites mediating is effects have remained uncertain. In the present paper, we review recent data suggesting that the midbrain periaqueductal gray may be a structure involved in the anxiolytic-like effects of cannabinoids.
