Fig. 1.

Anatomical pathways of chronic pain and neurotransmitters. The figure depicts the ascending and descending anatomical pathways of pain modulation. In the inner panel, neurotransmitters (depicted as squares) and receptors (depicted as V shapes) are illustrated. These include GABA (red), glycine (black), opiates (brown), norepinephrine (gray), glutamate (green), substance P (light blue), and serotonin (violet), each with their respective inhibitory (-) or excitatory ( +) activity indicated