Neurons of the parabrachial nucleus, nociceptive input, and pain pathways

The parabrachial nucleus (PBN) is an important pontine nucleus that receives and transmits different sensory information, including pain. The PBN is comprised of distinct pain pathways that play an important role in the manifestation of emotional behavior, autonomic reaction, and learning due to pain, especially in animals. The PBN is regulated by higher brain regions such as the hypothalamus, central nucleus of the amygdala, and periaqueductal gray. Moreover, the PBN also extends efferent projections to brainstem nuclei in order to modulate the pain state (analgesia or persistent pain). Therefore, these findings support the idea that the PBN is a critical hub region that integrates diverse sensory information, including pain, and provokes emotional behavior, autonomic reaction, and learning. In this chapter, we review the anatomy of the PBN and the function of neurons in the PBN as well as related pain pathways.