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How Nerves Work: Simplifying Complex Neuroscience

Updated: Apr 19


How nerves work

While there is plenty to learn about the nervous system, and doctors spend years in school studying how nerves work, this post will give an overview of pain in our nervous system and how it relates to:


  1. Neuroplasticity - our nervous system can learn.

  2. Thresholds - how much it takes to make our nervous system respond

  3. Nerve Conduction - nerves communicate with electricity


Neuroplasticity


The nervous system is one of the most complicated systems in the human body. The boss of your nervous system is the brain. This presents a significant challenge for the medical community because brains are unique like fingerprints. Even identical twins have different brains and different fingerprints.

While there is definitely a genetic piece to how your brain is formed, the human brain is what neuroscientists call plastic, meaning that it can adapt and change. Plasticity is a good thing because it allows our brains to learn and develop as we grow. It also means, however, that the things that we learn as children matter. While facing adversity in childhood does not guarantee that you will face challenges as an adult, it certainly is correlated with increased risk of developing chronic health conditions. (1, 2)

Let's take pain for example, part of how you process pain is actually learned. If you've ever spent time with small children, you may have seen a child fall down and scrape their knee. If this is the first time that has happened to them, when they are very young, they will often look to their parent before they decide what to do. If their mom panics, the child will likely begin to cry and get upset. The child sees the mother's anxiety, and responds accordingly. Similarly, however, if the mother is calm, and reassures the child, "You're ok." with a smile, the child will likely take a deep breath, reorient themselves, and get up to keep playing.

The tissue damage the child experienced with the scrape on their knee could be exactly the same in both scenarios, but the way the child learns to respond to it is different. This is what makes understanding pain so complex for healthcare providers. Everyone's body processes pain differently.

There are a variety of influences that a child might encounter while they are learning to process pain. For example, many cultures teach boys that it is not ok to cry about pain from a young age. Some religions believe that suffering is a sign of being punished by God, while others see it positively as an experience that will draw a person closer to God. Some children experience the anxious helicopter parent phenomenon, and subsequently learn to be fearful of injury and attentive to every little ache and pain. Perhaps a child has parents, teachers, or coaches who ignore them, mistakenly thinking they are being dramatic, when they in fact have a legitimate injury. This child might learn that they needed to do more to get attention for their injury in the future. Still other children experience neglect, and subsequently might learn not to pay attention to injuries that actually warrant medical attention. Some children encounter abuse at the hands of someone they trust.

In fact, almost all of us experience a combination of these scenarios and more, which ultimately come together to form our adult nervous system's pattern for interpreting information and responding to it. No two people share the same nervous system. This is why one size fits all solutions are often unhelpful in managing conditions like persistent pain, and others that affect our nervous system.


Thresholds


Our nervous systems have what we call a threshold for response. Temperature, pressure, and many other stimulus to our nerves occur on a continuum. If we apply warm water to our skin while washing our hands, it may be a pleasant sensation. There comes a point however, that the water is hot enough that it begins to become painful. If the water is hotter still, it may eventually burn our skin.

Similarly, there is a level of pressure on your skin that feels like you are being tickled, which is different than the pressure that feels like a comforting hug, and also different than a person squeezing your neck in a choke hold which becomes uncomfortable and painful. The stimulus, however, is the same in all of those scenarios. The question becomes, how much pressure does your body decide is comforting, as opposed to irritating or threatening?

The nerves in your hands and out in your body simply send a message to your brain saying, "something happened". As for what that "something" is, is ultimately up to your brain to decide. Whether it is temperature that your nerves sense, or pressure, your brain has to decide whether that level of stimulus is a good thing or not.

We believe this because of what we know about people with spinal cord injuries. If the spinal cord has been damaged and the messages can't pass from the nerves in your feet, up to your brain, you lose feeling in your legs. If you were to sit with your eyes closed and a person smashed your toe with a hammer, it wouldn't hurt because the message can't get to your brain to be interpreted.

Likewise, studies suggest that 60-80% of individuals who undergo an amputation, experience pain and other sensations in a body part that is no longer physically present.

(3). We would not say that all of those people are making it up. The effect is far too widespread. While the experience of pain is not "all in your head" in the sense that it isn't real, or you are making it up, we do believe that it is predominantly an experience that happens in your brain. While the person who underwent an amputation may have lost part of their limb, they didn't lose the part of their brain that processes information for that limb.


Nerve Conduction


When our nerves decide that a threshold has been met to send a signal to our brains, lots of things happen quickly. Chemicals change in our bodies that create an electrical current that passes from the end of one nerve to the next, transferring a signal along the pathway to our spinal cord and brain.

This works similar to the wiring in your house. Just like the wires in your house have a protective coating around them, your nerves do too. Nerves are coated with a myelin sheath that helps keep the electrical impulse contained so it moves smoothly along the little nerve wires.

Unlike the wires in your house however, our nerves are sending more complex information. Our nerves are capable of sensing a variety of different sensations including pressure, temperature, vibration, the position of your body, and whether something is sharp or dull. They also carry messages telling your body to move a muscle. There are special nerves the sense smells, transmit visual information for you to see, sounds for you to hear, and flavors for you to taste.

In short, our nerves are busy places. In truth, we don't fully understand how our nerves can differentiate all of that information. Our testing of the nervous system is somewhat limited. It's important to know that when someone has a nerve conduction study, the test is assessing if the information is passing from point A to point B and how fast it gets there. It cannot tell us exactly what kind of information your nerves are sending. This can be frustrating for patients experiencing pain and sensory problems who are told that their nerve conduction testing is normal.

For a better understanding of how the variety of sensations are processed in your nervous system, see Nervous System Highways.



This post is intended for educational purposes only and is not intended to replace individual medical advice. If you are interested in a personal consultation, call or select the Book Online option.


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