Normal synapse with ECS on the left: CB1 = cannabinoid receptor, EC = endocannabinoids (anandamide). When the postsynaptic neuron is activated, endocannabinoids are produced, released, and travel back to the presynaptic neuron where they activate cannabinoid receptors. On the right: delta-9-tetrahydrocannabinol, or THC, binds to the same cannabinoid receptor.