Pain as a concept

Chapter 10 endnote 26, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

Chronic pain is likely a misapplication of the concept “Pain” by your brain, as it constructs the experience of pain without injury or threat to your tissue.

Chronic pain is not a unitary phenomenon — it likely has many degenerate causes and manifestations. Based on the available evidence, it seems likely that chronic pain is caused by nociceptive sensory predictions (part of the "Pain" concept) that continue beyond an injury, past the point where the body has healed but the brain is not sufficiently processing the prediction errors; descending body-budgeting predictions may also enhance the intensity of nociceptive input to the brain (see also opiates can cause chronic pain via prediction and phantom limb syndrome).

Some evidence is consistent with this hypothesis. Chronic pain is associated with changes in the brain's opioid system. Also, people with stronger (functional) connections between body-budgeting/predictive regions (e.g., medial prefrontal cortex) and regions that control the body (e.g., the nucleus accumbens, a so-called "reward" region) are much more likely to develop chronic back pain after a single, intense episode of back pain. More generally, modified connections between body-budgeting (limbic) brain regions and sensory brain regions seems to play a role in making pain chronic.