The ascending pathway, which transmits sensations of pain to the brain, is regulated by neurons that descend from the brainstem – the descending pathway.[Steeds, 2016] These noradrenergic and serotonergic neurons downregulate the activity of neurons of the dorsal horn, thereby modulating the feeling of pain.[Steeds, 2016]
Reference:
Steeds CE. The anatomy and physiology of pain. Surgery 2016; 34 (2): 55–59.
Other references used on slide:
Purves D, Augustine GJ, Fitzpatrick D, et al. Neuroscience, 6th edition. New York, New York: Oxford University Press, 2018.
Urch C. Normal pain transmission. Rev Pain 2007; 1 (1): 2–6.