“That, at least, is the consensus of a new paper in Neuropharmacology:
There is a general consensus that the effects of cannabinoid agonists on anxiety seem to be biphasic, with low doses being anxiolytic and high doses ineffective or possibly anxiogenic. Besides the behavioural effects of cannabinoids on anxiety, very few papers have dealt with the neuroanatomical sites of these effects. We investigated the effect on rat anxiety behavior of local administration of THC in the prefrontal cortex, basolateral amygdala and ventral hippocampus, brain regions belonging to the emotional circuit and containing high levels of CB1 receptors. THC microinjected at low doses in the prefrontal cortex (10 ?g) and ventral hippocampus (5 ?g) induced in rats an anxiolytic-like response tested in the elevated plus-maze, whilst higher doses lost the anxiolytic effect and even seemed to switch into an anxiogenic profile. Low THC doses (1 ?g) in the basolateral amygdala produced an anxiogenic-like response whereas higher doses were ineffective.
In other words, a good high works in the prefrontal cortex and ventral hippocampus while a bad high turns on the amygdala. As most pot smokers eventually discover, there is a fine pharmacological line between comic relaxation and vague paranoia.”
(via The Frontal Cortex)
(see also “Is Weed The New Prozac?”)