top of page
  • colinliggett

The Neural Edge - What’s Yours?

Updated: Feb 22

Your "Neural Edge" is when the nervous system receives enough sensory or limbic information perceived as threatening that it is forced into a safety response. Our nervous system is constantly in flux between safety and threat. Millions of neurons transmit sensory and limbic information to the brain every second. If the accumulation of perceived threats pushes past the neural edge, a compensatory response occurs.

When the nervous system is pushed past its "neural edge," it can choose to respond by causing inhibition or overactivity locally (one or more muscles) or globally (all muscles).

In SensoriMotor Repatterning (SMR), we look for dysfunctional movement patterns due to the nervous system being pushed past its "neural edge".

Each muscle can be tested for neural function via manual muscle tests… standardized positional resistance tests that correlate to the optimal alignment of a specific muscle.

Muscles can also be tested in groups called subsystems or myofascial chains of muscles.

Further, I describe" functional testing" as testing positions representative of everyday movement (e.g., a squat) or sport-specific movement (e.g., an overhead throw).

With SMR, clinical testing can reveal a complex pattern of muscle dysfunction that plots out the mechanisms that cause symptoms. Here is an example of how complex a client's presentation often is.

A client complains of right shoulder pain when using the computer. With prolonged use, headaches start at the base of the skull and radiate to the forehead. Muscle testing when supine (lying on their back) shows inhibition of the infraspinatus and subscapular muscles caused by an old shoulder injury. When seated hypersensitive stretch receptors in the left sacroiliac (SI) joint send faulty signals to the brain, the cumulative effect of this sensory input, combined with the old shoulder injury sensory inputs, causes a complete downregulation (inhibition) of all but two of the right shoulder muscles, as well as inhibition of the upper trapezius and levator scapular muscle, and overactivity of the suboccipital muscles. These muscles are at the base of the skull, which triggers the start of a headache in this area.

Prolonged sitting causes the head to slump forward, causing hypersensitive stretch receptors between C03 and C04 of the cervical spine to engage, which cumulatively causes the threatening signals reaching the nervous system to push past its global "neural edge," causing all muscles to inhibit in this position, further increasing headache symptoms to the degree that several hours after being at the computer the headache will still be present.

Sounds complex? It's actually way more complicated than this. All presentations are always multifactorial. Our nervous system is an incredibly complex system of safety responses. In the initial treatment session, I have a client lying supine (on their back) and testing roughly 20 muscles bilaterally (40 in all), creating a list of dysfunctional muscles on a whiteboard. Then I try to find an example of a sensory input that pushes them past their global "neural edge" into complete inhibition of all muscles. For some, this may be as simple as sitting up, others standing, others positioning the eyes in a specific direction, having them go to their end-range of motion in a joint, etc. I will always be able to find an example of global inhibition, with no exceptions.

I then tell the client there may be 1000 ways I can stimulate the nervous system to cause global inhibition and more for local inhibition of muscles. We want to avoid going through and finding every faulty sensory input, it's ineffective. Imagine the nervous system is organized like a pyramid, with 1000 dysfunctions at the base layer, but maybe only 10 dysfunctions at the top of the pyramid. If we can find and treat a high-level dysfunction at the top of the pyramid, such as dysfunctions from old injuries or surgeries, this will have a likely trickle-down effect of correcting 300 of the 1000 dysfunctions.

For this reason, the first session is dedicated to looking for old dysfunctions from injuries and surgeries. Suppose you had a concussion as a child, and your nervous system didn't manage to resolve this completely. In that case, any later injury is likely not fixed, as the nervous system was dealing with the tangled mess from the concussion. The nervous system is incredibly inapt at correcting dysfunction. If I can be detailed enough in providing the functional part of our brain information about a dysfunction, it can immediately correct this due to neural plasticity, and it will remain corrected indefinitely. There are twelve separate dysfunctions I can look for and identify in the nervous system for any one injury/surgery.

When we have all the muscles working when a client is lying down, we retest them standing. Just because muscles are working lying down does not mean they are likely to work standing. The neural load on the brain during the act of standing on two legs is intense, it uses up a huge amount of brain processing power, meaning it is much easier for sensory input to push the nervous system past its neural edge, causing a muscle to locally inhibit, that would not inhibit in a seated or lying position.

Later in the flow of sessions (usually the third), I check functional positions for dysfunction, e.g., squats, rotational patterns, and end ranges of motion. For high-level athletes, we can go into sport-specific movement, eccentric and concentric contractions through complete ranges of motion, etc. Have you had an injury playing soccer? What's the likelihood that putting on your cleats is enough sensory recognition for your limbic system to assume you are about to play the sport you previously injured yourself in and gets pushed past its neural edge into a safety response? From experience, it's very likely, and fascinating!

From a therapist's perspective, in years gone past, I would state to clients, "dysfunction A was inhibiting muscle B. By resolving dysfunction A, muscle B is now functional." It may be a much more accurate statement to say. "By resolving dysfunction A, we gave your nervous system enough safety credit that it is no longer being pushed past its neural edge concerning muscle B, and muscle B is now presenting as functional." As I now realize, there may be many ways we can resolve dysfunction in the nervous system to bring muscle B back to normal function. The trick to being a standout therapist is to ensure you are doing so at the highest level possible, in how the nervous system organizes itself and prioritizes safety, thus maximizing results with minimal intervention.

You can book an SMR appointment with me here

bottom of page