Pain is not a direct readout of tissue damage — it's a signal constructed and re-shaped at multiple checkpoints between the injury site and conscious awareness, any of which can be opened, closed, amplified, or fooled. A tour of nociceptors and the two fiber types that carry different pain qualities, the spinal gate that rubbing an injury actually closes, why a heart attack can feel like a sore left arm, and how chronic pain can persist as a real neurophysiological state long after the tissue that started it has healed.
Central-Sensitization
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How Pain Actually Works