Breaking Down Pain: How to separate the physical sensation and emotional experience

Pain, while unpleasant, is essential for survival. It triggers our reflex to remove our hand from a hot stove, teaches us to avoid harm (like refraining from touching the hot stove again!), or signals danger in our body in the case of infection or injury. It can be broken into two components: 1) the physical sensation of pain, sensed by the neurons in our skin or other organs, and 2) the emotional experience of pain, which is perceived in our brain. In circumstances of extreme pain like after surgery or with chronic injury, pain is broadly treated with opioids despite their serious side effects, like opioid-use disorder. To treat pain more precisely and safely, scientists have been working to better understand how to separate pain into the beneficial sensation and the detrimental emotional experience.

A specific region of the brain called the anterior cingulate cortex (ACC) is known to be important for processing the emotional side of pain. In this study, scientists pinpointed the specific subset of neurons in the ACC that are related to pain processing by identifying which ones respond to painful stimuli and are altered when the animal was given an opioid pain reliever. Then, they used an interesting genetic approach to target only these neurons in the ACC,preventing them from responding to any stimulus. Incredibly, in mice with a chronic nerve injury, silencing these specific neurons achieved a similar pain-relieving result as giving the mice an opioid! This points to an interesting new strategy to treat pain without the risk of opioid addiction.

The discovery of these ACC neurons helps us understand how we might be able to treat the suffering associated with pain without numbing the sensation in general. By breaking pain down into its component parts, we can hopefully figure out how to keep the adaptive aspects while treating the unpleasant ones. 

This study was led by Corinna S. Oswell, Sophie A. Rogers, and Justin G. James at the University of Pennsylvania.

Managing Correspondent: Sophia Renauld

Press Article: Chronic pain could be eased by uncoupling the sensory and emotional experiences, Nature

Original Research Article: Mimicking opioid analgesia in cortical pain circuits, Nature

Image Credit: Photo by Federico Lancellotti on Unsplash