How is Pain Processed in the Brain?

What they did: A team of researchers from Stanford University led by NYSCF – Robertson Neuroscience Investigator and Assistant Professor of Anesthesiology, Neurosurgery, and Perioperative and Pain Medicine Grégory Scherrer, PhD, PharmD, examined how our brain activity gives rise to the unpleasant emotion of pain.

What they found: The researchers identified a group of neurons in the amygdala, a brain region associated with emotion, that contribute to the negative emotions of pain.

Why it matters: The opioid crisis is driven by a lack of effective and non-addictive chronic pain medications. This study sheds light on the neural basis behind pain and identifies a possible target for the development of safe therapeutics.

 ———————————————————————————————————————————————–

Contrary to how it makes you feel, the unpleasantness of pain is a typically a good thing. If you get a cut or bump your head, processing the experience as painful is a sign that what happened to you is bad and should be avoided in the future. But for the 100 million Americans with chronic pain resulting from cancer, recovery from surgery or injury, neuropathy, or other conditions, the ongoing experience of strain and discomfort can be debilitating and lead to psychiatric disorders such as anxiety and depression. Additionally, the absence of effective and non-addictive chronic pain medications is the major factor driving the opioid crisis.

Most pain research focuses on what happens before the pain signal reaches the brain (how it is picked up by your nerves and relayed through your spinal cord). But it is your brain that processes the affective component of pain—the feeling of unpleasantness. In a new study published in Science from researchers at Stanford University led by NYSCF – Robertson Neuroscience Investigator and Assistant Professor of Anesthesiology, Neurosurgery, and Perioperative and Pain Medicine Grégory Scherrer, PhD, PharmD, scientists explored the neural basis of pain processing and what leads to its negative emotions.

To do this, the team examined the brains of mice who were exposed to painful stimuli (such as a pin prick or uncomfortable levels of heat or cold). Brain imaging revealed that in the presence of these stimuli, neurons in the basolateral amygdala—a brain region associated with emotion—became active. When this group of neurons was silenced, mice showed reduced pain-associated behaviors (such as reflexive withdrawal or attempt to escape) in response to the painful stimuli. This suggests that this part of the amygdala plays an important role in assigning unpleasantness to the pain experience.

Management of chronic pain currently costs the nation $635 billion a year, which is more than the yearly costs for cancer, heart disease, and diabetes combined.

“There’s really no good treatment for chronic pain in humans, and that’s a major driver of the opioid epidemic,” Dr. Scherrer said in an article from Stanford. “But you’ll notice, patients who take opioids for pain report that they can still feel the sensation of pain but say it’s less bothersome — the emotions of pain are different. Our big future hope is that the cells in the basolateral ensemble could be a tactic to curb the ailment of pain without causing addiction and thus, ideally, act as a possible substitute for opioid treatment.”

Paper citation:

An amygdalar neural ensemble that encodes the unpleasantness of pain.
Corder G, Ahanonu B, Grewe BF, Wang D, Schnitzer MJ, Scherrer G.
Science. doi: 10.1126/science.aap8586.