The endocannabinoid system modulates neurotransmission at inhibitory and excitatory synapses in brain regions relevant to the regulation of pain, emotion, motivation, and cognition. This signaling system is engaged by the active component of cannabis, Δ9-tetrahydrocannabinol (Δ9-THC), which exerts its pharmacological effects by activation of G protein-coupled type-1 (CB1) and type-2 (CB2)...