Pain and Hunger: Why Sensory Pathways Matter
Pain Neuroscience Education (PNE) has gained popularity in recent years, with proponents arguing that pain is more about brain signals and emotions than about sensory input from the body.
Drawing from philosophies like the "pain neuromatrix" developed by Ronald Melzack, PNE advocates claim that pain is entirely a brain-generated experience, influenced by our thoughts, beliefs, and emotions.
But what if we compared pain to another fundamental experience that most of us understand well: hunger?
In this post, we’ll use hunger to challenge PNE’s neurocentric view and explain why sensory pathways from the body are essential for pain perception.
Hunger and Pain: Parallel Experiences
Both hunger and pain are essential survival signals based on homeostasis becoming disturbed.
Hunger motivates us to eat, while pain drives us to protect our bodies from injury.
Both sensations involve a complex interaction between brain signals and bodily inputs.
However, just as you cannot experience hunger without input from your body, you cannot truly experience pain without the sensory pathways that relay signals from the affected area.
How Hunger Works: A Brain-Body Partnership
Hunger is not just "in the mind."
It’s a perfect example of interoception—the way our brain interprets internal body signals.
When you’re hungry, your brain is responding to several cues from the body:
The stomach stretches or contracts, sending signals via the vagus nerve to the brainstem.
Hormones like ghrelin are released, which signal hunger to the hypothalamus.
The body’s energy status is monitored, and when glucose levels are low, signals are sent to urge us to eat.
While emotions or habits can influence hunger (like seeing food commercials), the physical sensation of hunger still depends on these signals from the body.
The brain alone cannot generate the feeling of hunger without these sensory inputs.
Pain Needs Sensory Pathways, Just Like Hunger
Pain works similarly to hunger.
It’s a multi-dimensional experience, combining sensory input with cognitive and emotional components.
However, sensory pathways from the body are crucial for the brain to create the pain experience.
Just as the brain responds to signals from the stomach to generate hunger, it also relies on sensory signals from the affected tissue to generate pain.
Here’s why sensory input is critical in pain:
Nociceptors (homeostatic sensory receptors) in the skin, muscles, or joints detect potential damage (heat, pressure, inflammation) and send signals through the spinal cord to the brain.
The brain integrates these signals with emotional and cognitive factors, like fear or anxiety, but without the original sensory input, the pain experience wouldn’t happen.
In cases like phantom limb pain, while the brain can generate a pain experience in the absence of a limb, it’s often because the brain’s neural map still includes sensory memories from that missing limb. This phenomenon shows how pain requires a connection to past or present bodily sensations.
PNE's Neurocentric View: Where It Falls Short
PNE proponents argue that pain can exist without any sensory input from the body, relying heavily on the neurocentric "pain neuromatrix" theory.
According to this model, the brain constructs pain purely from a mix of emotions, past experiences, beliefs, and sensory inputs—sometimes even in the absence of any injury.
While it's true that pain is influenced by these factors, PNE oversimplifies by suggesting that pain is predominantly a "brain-made" problem.
This model is helpful for understanding some aspects of chronic pain, but it’s dangerously incomplete.
It implies that pain can exist without any ongoing input from the body, which is misleading and can lead to overemphasis on cognitive strategies (like reframing thoughts or beliefs) while ignoring the sensory pathways that play a fundamental role in pain perception.
Why Sensory Pathways Matter in Pain
Let’s return to the hunger analogy.
Imagine if you were told that hunger is just an emotion, purely generated by the brain, without any connection to your body’s energy needs.
You might be able to delay hunger temporarily through distraction, but ultimately, your body’s signals would push back, demanding attention.
The same is true for pain: while thoughts, emotions, and beliefs can influence pain, the underlying sensory inputs cannot be ignored.
Misleading patients: The PNE approach often suggests that pain can be "thought away" by changing beliefs or reframing the way patients think about pain. While these strategies can help, they neglect the reality that pain still needs sensory input from the body to fully exist. Ignoring the sensory aspect risks alienating patients who feel that their pain is being dismissed or minimized as "an output of the brain."
Manual interventions: Techniques like manual therapy, dry needling, or exercise affect the sensory pathways and are vital in managing pain. These are often overlooked by PNE advocates who favor cognitive strategies over hands-on treatment.
Moving Toward a More Balanced Understanding of Pain
The brain and body are in constant communication, and both are essential in understanding pain.
Sensory pathways from the body provide the brain with crucial information that influences how pain is experienced, just as signals from the stomach influence how hunger is perceived.
Dismissing these pathways in favor of a purely brain-centric model like the "pain neuromatrix" oversimplifies the complexity of pain.
Conclusion: We Need Both Brain and Body in Pain Management
Incorporating sensory pathways into pain education helps create a more comprehensive and accurate understanding of pain.
Instead of focusing solely on the brain's role in generating pain, we should recognize the critical role that body signals play, just like in hunger.
Cognitive strategies and emotional regulation are essential, but they must be balanced with respect for the sensory input that drives much of the pain experience.
Pain isn't just in your head—it’s in your body too.
For effective pain management, we need to move beyond the neurocentric models and embrace a more balanced, whole-body approach.