The human body is a magnificently complex structure. Atoms form molecules, molecules form cells, cells form everything we are. Every process in our bodies from a macro level (running, jumping, dancing) through to the micro level (cellular diffusion, energy production, even conscious and subconscious thought) is controlled by our central nervous system- “the Brain”. Understanding such a highly complex structure can be difficult, and for this reason oversimplification can be used to gain a better understanding. So, as Albert Einstein said, “if you can’t explain it to six-year-old you don’t understand it yourself”. Get ready to head back to primary school…

Imagine you are a futuristic robot, just like Optimus Prime! You have arms and legs, a head and a torso, much like a human. Inside your head is a massively powerful computer. This computer has the fastest processing speed, the most RAM, top of the line graphics card, internal fluid system, protective casing, “the works”! From this computer comes a complex system of wiring that permeates through the entirety of your robotic structure ending with a series of highly effective sensors. These sensors detect all movements of the robot, including the speed, force and direction of these movements. The sensors are also receptive to touch. The sensors can differentiate between sharp and blunt, hot and cold and the texture from stimulus. They can perceive the stretch and deformation of the robot’s external layer. They constantly sense where each part of the robot is at any given time (like an internal GPS). Some of these sensors (called the robotic nociceptors) specifically detects things that are potentially damaging or threatening to the robots’ structure. All this information is sent to the central computer at up to 120m/s! It allows you as a robot to safely and efficiently go about your happy robot day.

Let’s put it in context. So…You and your robot family are walking through the park and you stand on a nail! The sensors in your feet immediately send information to the central computer. A combination of force, sharp, outer layer rapid stretch as well as “DANGER, DANGER, DANGER!” from the nociceptors. The information is commuted extremely quickly and is surmised by the central computer to be an abnormal, unplanned, unexpected stimulus, potentially damaging to the robotic foot. Red lights are flashing, sirens are blaring in the control centre as the outcome from this information is “PAIN”.

Although this whole process is amazingly fast, by the time the computer has realized that the foot is in danger and formed a plan to mitigate damage it is too late, the nail is firmly embedded in the robots’ foot. However, the robot is so effectively and efficiently created that a bypass circuit has been created. The information is also sent through another circuit called the “reflex arc”. This bypasses the main wires system to the central computer and comes straight back to the hydraulic extensors of the robot’s knee. These are activated instantaneously to bring the foot away from the nail and the damage is minimized.

A reflex is a sub conscious reaction to a stimulus that is ingrained into our body’s hardware. The human body has many different reflexes (gag, sneeze, vestibulo-ocular, trip, etc), as well as infant reflexes like sucking reflex, palmar grasp, moro reflex etc. All of these are processes are designed for life preservation without requiring a full process of conscious thought.

In this example of the robot, pain is a valuable outcome from a complex process of sensation and computing to avoid potential serious injury. How does this impact you as a human?

Initial pain is a normal bodily response. It gives valuable information as to what is going on in the body.
Listen to your body, it is much smarter than you are!


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About the Author:
Alex Lowen is a Sports Lab Physiotherapist. Alex believes in creating independence for his clients. He has a firm belief in evidence based practice and enjoys delving into the tough and complex cases. Alex is also the master of the “dad joke”.