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O Body Part, Where Art Thou? (Says the Brain)

June 30, 2017 • Pain Science

This blog starts with a familiar story. One I have personally experienced, and one I expect other parents have too. You are shopping in a large grocery store with your young child, a long list of items to get, and need to get in and out quickly. After comparing prices on pasta sauce you lean over to say something to your daughter, but she is gone!?! “She was just there”, you think (as you mumble some unheard words under your breath). A very mild panic begins. You look down the next aisle, not there. The panic slowly increases. The longer she is missing the more your mind races to all the negative outcomes possible as your heart rate and walking speed increase. You feel a combination of nervousness, fear, anxiousness, and anger that she did not listen to your 8th request to stay by your side. Though, most of all, you feel a deep concern for her safety. Then it happens, you find her! Safe and sound, six aisles over in the candy section, without a care in the world, like nothing happened, happy to see you because she wants to buy some gum.You hug her, she gets in trouble, and of course she does not get the gum. The lost is found. All the emotions quickly settle as you finish shopping.

For some it was not a lost child. It may have been a missing pet, wedding ring, or money. Whatever valuable item was lost the inevitable race to find it began. A mix of emotions followed until the lost item was found. The more valuable the item, the more emotion and reaction felt.The response to losing something valuable is a seemingly universal human trait we all share.

Can you remember a time you lost something valuable and how you felt?

How we respond to something being lost is analogous to how our brain may respond when it loses sight and awareness of a painful body part.To many in the world of pain science this is not a new concept. A highly skilled PT I recently spoke with said he has been considering blurry, fuzzy, and smudged cortical brain maps in his assessment and treatment for at least 10 years. I am willing to bet though, a lot of PT’s have yet to discover the untapped potential for considering cortical brain maps as part of a multimodal approach for treating pain.

You likely remember learning of cortical brain maps in neuroanatomy, but you may not have learned that these brain maps can become altered in some cases of pain. Neuroscience has told us for years, starting in the 1930’s with Dr. Wilder Pinfield, that our physical body is neurologically represented within the brain in the form of neuroplastic cortical maps. These brain maps, named primary somatosensory cortex (S1- homunculus) and primary motor cortex (M1), provide us with conscious body perception, awareness, and appreciation of self.1

Adriaan Louw often says:

“Brain maps are genetically coded, environmentally sculpted, and change within minutes according to any sensory input they receive”

Maps are normally very sharp and clear when they receive regular somatic and peripheral input. These inputs give the brain an ability to see each body part clearly, to optimize the function of brain outputs. Maps are extremely neuroplastic and are highly responsive to any sensory input received. What you feed a map, informs a map. Lots of practice playing soccer makes you game ready, while little or no practice alters your timing making you ineffective and less competitive. I could go on with old adages like practice makes perfect, use it or lose it, etc, but this is the heart of cortical brain maps. When it comes to brain maps the more you use it, the sharper it is.

Focused research of cortical maps surfaced while studying complex regional pain syndrome and phantom limb pain. However recent research shows that cortical reorganization may be present with many chronic conditions, especially chronic lower back pain.2

My current understanding of smudging says that in times of persistent pain, or intense acute pain, the part or parts of our map involved with the pain may shift in how it excites, inhibits, and interprets sensory information locally at the map and at surrounding neurons. This shift can be viewed as a reorganization of brain circuitry (unhealthy neuroplasticity). A normally crisp and clear, genetically coded map may begin inviting neighboring neurons to join in its response to threat as a means to protect. While the invited neighbor neurons excite to join brain map neurons; the inviting cortical map neurons disinhibit allowing new synaptic relationships to develop between the two neuron groups.The invited neighboring neurons now pollute the once sharp and clean maps. This map pollution is called brain map smudging. The genetically programmed map has been changed with unhealthy plasticity accompanied by potentially negative sculpting from the environment. This affects map output! In some cases once maps are smudged, they may stay smudged until treated. Considering the initial story in the blog, think of smudged as being lost.

S1- homunculus map smudging seems to be a potential biological and physiological change that can occur with any injury or bout of pain. Many view this as one of many potential ways a brain may attempt to protect itself from perceived threat. The evidence suggests that smudging can occur for many reasons, such as the one outlined above, but there are many thoughts and ideas about how and why smudging happens without a definitive causation. It is indeed a complex neuroplastic phenomenon that will require more study to fully understand.3

So we pause here, to consider the emotions and feelings experienced when we lose something valuable. We also consider that the brain itself may react in a similar way when it loses a part of its cortical map to smudging. Once a part of the map has been smudged, or lost, our brain may react with the same nervous, fearful, anxious, angry, and concerned emotions. The influence of these emotions likely drive output actions and behaviors that promote and sustain protective strategies until the lost is found.

Next time, I will explore some clinical presentations to consider when trying to decide if the patient you are treating is secretly asking “Oh Body Part Where Art thou?”

What are your thoughts and responses? I would love to hear them.



  1. Wand BM, et al., Cortical changes in chronic low back pain: Current state of the art and implications for clinical practice, Manual Therapy (2010), doi:10.1016/j.math.2010.06.008
  2. Moseley GL. I can’t find it! Distorted body image and tactile dysfunction in patients with chronic back pain. Pain 2008;140:239 -243
  3. Apkarian AV, Baliki MN, Geha PY. Towards a theory of chronic pain. Progress in Neurobiology 2009; 87(2):81e97.

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Commented • July 14, 2017

Thanks for reading Ken. I appreciate your ideas here. It is definitely fun and exciting to let our imaginations run and work through complex phenomenons such as brain map smudging. As I consider this phenomenon I think as our bodies shift to protection after an injury (your example of ankle sprain) it also starts the slow process of trying to shift out of protection back to its normal (genetically programmed state) are soon as it can. What I think is fascinating are the thoughts and environmental variable they may convince the map to stay in a protected state... We live in exciting time for our PT profession! Jarrod


Commented • July 14, 2017

Hi John, Thanks for reading. I appreciate your input about the idea of how these concepts of smudging may begin to reframe the way we all think of traditional manual therapy. I think we will see more on this in the coming years. Considering the deeper neurophysioloy and neurobiology of what we are doing with our hands is very cool. Then the hands on combined with helping a patient understand what the manual therapy may be doing, to re-map their brain map, is likely a potent combination. Jarrod

Ken Tanpinco

Commented • July 12, 2017

Great article that got me thinking about why smudging occurs. Since cortical refreshment happens after an acute injury (lets use an ankle sprain as an example), the motor cortex may become smudged in order to inhibit movement of the affected ankle. This would do 2 things. 1. Immobilization of the newly injured area and 2. Clearing previous motor sequencing so that new modified movements/GAIT can be programmed to protect and rest the ankle during tissue remodeling. Clearing the slate for this to occur may allow developmental patterns of movement to once again emerge. The brain would then treat new remodeling tissues as the infants they once were, gently. Neurons would learn and grow (reprogram) at the same rate these new tissues mature. The sensory cortex would respond in the same manner by learning new input from a blossoming ankle during this nurturing phase of growth. Sounds like a great Hollywood script doesn't it ? Thanks for getting my imagination running today.

Ryan schallenberg

Commented • July 2, 2017

Another excellent blog, jarrod and great analogy.

John Kiesel

Commented • July 1, 2017

Jarrod, thanks for the insightful story and highlighting a concept that is important. Introducing the concept of smudging to patients over the last several months has been a game changer for me, but more importantly reframing the way I think about some of my interventions to incorporate the idea of changing the 'maps' has made me more effective. Using manual therapy in a way that involves sensory discrimination and increasing active patient involvement to discern specifically where manual interventions are being targeted can provide more input to the maps (ie. asking a patient during PA mobs whether you are on L3 or L5). The greatest benefit of introducing this concept to patients is informing them that the maps can shift or 'sharpen' rather rapidly when focused practiced is performed regularly. This offers hope and gives them some motivation to perform their homework.

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