The brain has a unique ability that allows it to change, to modify and to re-integrate with itself: this is known as Neuroplasticity. No other organ has this special property. Some of the common functions of neuroplasticity apply to balance (the vestibular system), movement (the locomotor system), and learning new skills, otherwise known as cognition. Could it be possible to remove or unlearn something we experience, such as an ongoing pain syndrome?
The Sensory Pathway:
Our somatosensory system enables us to feel touch in our body. Sensory receptors reside in tissues such as our skin, muscles, joint capsules, and ligaments; these receptors detect sensations such as vibration, heat, cold, pressure and stretch, etc. They detect this information and send it to the brain via tract fibres (our biological highways) that reach the brain via the thalamus (the relay station in the brainstem), and then send it through to higher brain centres, where the information is interpreted and made sense of. This allows us to experience the world around us. It is remarkable to think that the only information that is reaching the brain is in the form of electrical impulses, which the brain has the ability to decode, and this electrical information allows us to feel the breeze on our skin, or the warmth of the sun’s rays on a hot day. It is the brain that computes this electrical information and turns it into a sensory experience.
A painful experience is facilitated by particular receptors called nociceptors. Nociceptors detect actual or potential tissue damage in the body and then send these electrochemical signals to the brain where they may or may not, depending on context, interpret these as a painful experience. Pain has both a sensory and an emotional component. This implies that one can experience the suffering of pain without having actual tissue damage, an example of which is phantom limb pain. Contrastingly, the converse can occur, such as a rugby player sustaining a stud injury on the forehead during a match without being aware of it.
This brain, using higher order functions, has the ability to interpret our peripheral sensory sensation with particular reference to a pain experience. This is called the Top-Down or Descending Noxious Inhibitory Complex (DNIC) process, which modulates and effects our experience of pain. What is the value in knowing this information? This knowledge enables us to evaluate the difference between injury and pain as these are, evidently, not the same thing. We can interpret our pain and determine how we could possibly eliminate our painful experience from both the peripheral level of injury (such as rubbing the painful elbow you just knocked) and from the top-down (DNIC) higher order mechanisms.
The Principles of Neuroplasticity:
In summation, we can use our minds to control bodily sensations, particularly the sensory experience of pain. An example of this is in the management of phantom limb pain, which is when one experiences pain in an amputated limb. In this case a mirror is placed over an existing limb while being exercised and simultaneously observing the “missing” limb in the mirror’s reflection. This produces a change in the mapping of sensory information in the sensory cortex of the brain, owing to the re-visualization of the missing limb, thus tricking the brain into seeing what used to be the now missing body part. This normalises the sensory mapping process in the now altered cortex, which allows for a reduction or cessation of the pain. Repeating these exercises over time allows for a more permanent reduction of pain. This implies that neuroplastic change can occur quickly for the worse, such as the development of chronic phantom limb pain resulting from the amputation of a limb. Conversely, however, it can also be restored relatively quickly, sometimes within the very first session of mirror retraining.
Alternatively, we can affect our sensory experience in the periphery (the skin) for the benefit of pain relief. This is achieved by utilising applications directly to the skin such as massaging, rubbing, applying some taping, applying a brace to an injured joint, or applying an ice pack for acute injury. In the case of manual therapy, as may occur in Chiropractic treatment, both peripheral and top-down mechanisms are at hand in the relief of pain acquired from treatment. What is of particular interest to me is the latter; the integration of the top-down mechanism is something I use when treating patients.
The Journey of the Interpretation of Pain:
As mentioned, electrochemical signals reach higher brain centres via the thalamus (the relay station) at the brainstem level. The thalamus then sends these electrochemical signals to various parts of the brain before reaching the sensory cortex where they may or may not be interpreted. But before reaching the sensory cortex, they may pass through various areas of the brain such as the limbic system, where all human emotion is generated. They may pass through the hippocampus where memory is stored. They may pass through the insula where our value for things, experiences and circumstances is stored. They may pass through the anterior cingulate cortex, which has a role to play in emotion processing and behaviour regulation. They may pass through the amygdala, which processes fear, anxiety, and anger, or through the prefrontal cortex, which regulates our personality and intelligence. It is only when such fibres reach their destination in the sensory cortex, tainted with having transcended through some of these areas, that the brain then perceives this modified sensory experience.
Put in Practise:
If the context behind the clinical encounter is of value to the patient by virtue of my behaviour, professionalism, knowledge, expertise, and demeanour, and it subsequently positively stimulates these areas of the brain I mentioned above, the brain has a way of modulating the sensory information at the time, which allows for an overall pain inhibiting perception at the higher brain level. This briefly describes the therapeutic effect that I may have on a patient when they present for pain relief or are searching for answers to their painful maladies. Further pain inhibition processes can be sought using pharmacological intervention when required, as well as building on the possibility of neuroplastic change in the brain by employing further valuable tools such as mindful meditation, exercise therapy, mirror box training, education in the form of pain science, sleep hygiene and so on.
It is in understanding some of these processes that one can shift a person from suffering, and all that it entails, to living a better quality of life with less suffering, sometimes even in spite of still being in pain.
(Acknowledgement to Andrew Huberman for some content acquired from the Huberman Lab Podcast, 1 March 2021 “Control Pain and Heal Faster with Your Brain”.)
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