Neural circuits of pain and itch processing involved in anterior cingulate cortex
Anterior cingulate cortex (ACC) is widely considered to be the most important part of the brain's limbic system. Previous researches have shown that ACC plays a significant role in consciousness and behavior, including emotion, sensory, motor, memory, nociceptive processing, etc. Among these connections, nociceptive processing, especially pain and itch, has always been one of the prior research programs for the field of medicine. In recent years, the development of new techniques and advance in neurobiology has led to our new understanding on the link between ACC and nociceptive processing. In addition, neurophysiologic research has revealed that multiple peptides and neurotransmitters, including opioid peptides, glutamate, serotonin and dopamine, are involved in the mechanisms of modulation of nociception by ACC. In this review, we examine a wealth of recent neuroanatomical and neurobiological research that involves ACC and nociceptive processing, and provide a comprehensive review of the neural circuits of pain and itch processing in ACC, and the glutaminergic and opioidergic circuits are especially discussed.