From Tissues to Brain: A New Model of Pain
OLD: Biomedical Model
Pain is an input signal from damaged tissues. It's a direct measure of physical injury.
NEW: Neurotag Model
Pain is a protective output from the brain when it concludes the body is in danger.
Key takeaway: Pain doesn't equal damage. It equals a perceived need for protection.
What is a Neurotag?
The Orchestra Analogy
A neurotag is a distributed network of brain cells that fire together to produce an output (like pain, movement, or emotion).
- Neurons are Musicians: A single neuron can be part of many different neurotags ("symphonies").
- Overlapping Networks: This explains why thoughts, emotions, and context can influence pain. The neurotag for "fear of reinjury" might share neurons with the neurotag for "low back pain."
- The Output Defines the Neurotag: When this network fires, the resulting experience is what we call pain.
How Acute Pain Becomes Chronic
Facilitation & Sensitization
The nervous system "learns" pain. The more a pain neurotag is activated, the more efficient it becomes. The activation threshold lowers, meaning less input is needed to create pain. (Hebbian Learning: "Cells that fire together, wire together")
Disinhibition & Imprecision
The brain's inhibitory processes weaken. The pain neurotag loses its specificity and starts firing imprecisely, activating nearby neurons. This explains pain that spreads and is triggered by previously neutral stimuli.
Cortical Smudging
The brain's maps of the body (cortical representations) lose their distinct boundaries and overlap. This is the anatomical result of imprecision and leads to sensory deficits (poor localization) and motor deficits (poor coordination).
Retraining the Overprotective Brain
The goal is to provide the brain with credible evidence of safety to reduce the perceived need for protection.
Pain Neuroscience Education (PNE)
Reconceptualize pain by explaining its biology. Understanding pain changes pain by reducing the threat value of sensory information and preparing patients for active therapies.
Graded Motor Imagery (GMI)
Synaptic exercises to target cortical smudging. Progresses from limb laterality to imagined movements to mirror therapy, gradually re-engaging neurotags without provoking pain.
DIMs & SIMs Framework
Help patients identify their unique Dangers In Me (threats) and Safeties In Me (safety cues). The goal is to consciously minimize DIMs and maximize SIMs to tip the brain's balance away from protection.
Manual Therapy & Isometrics
Create a 'prediction mismatch' with novel, non-threatening input. This unexpected safety signal prevents the pain neurotag from activating. When the CNS alarm stays off, pain and movement thresholds immediately, but temporarily, increase.
