Recently a student of mine asked me about interoception versus proprioception. Well, this is complicated because there’s another word, exteroception, to add to the mix. All three terms are relevant to our overall well-being and how our body and mind connect. If the human body were easy to understand, we wouldn’t have to worry about diseases or disorders as we age. Alas, it’s just not that easy, because, quite simply, we are complex.
All three words do relate to one thing: how we perceive and sense things both within our body and the world around us.
Let’s start with a little history lesson of what I’m going to simplify and call “Body Sense” (which is well defined in the MELT Method book and a key component of my Living Body Model), the scientific basis of the physiological feedback mechanisms. It started with the notion that the human body had the ability to sense positions and movement. Going way back to 1557, Julius Caesar Scaliger described this as a “sense of locomotion.”
So this concept may seem “new” to people but really, folks, is anything new in what we know today?
Fast forward 300 years to Charles Bell who discussed things like “muscle sense,” which was one of the first descriptions of the feedback mechanisms on a scientific, measurable level. This was how we viewed the body—as a super brain that carried commands to the muscles and the muscles reported back to the brain on their current state of action and well-being. However, in 1880 we discovered it wasn’t just muscles that reported back— but also tendons, organs, and other structures like our skin that were taking in information and sending it to the brain prior to the brain sending messages to the body at all.
But it wasn’t until 1906 that Charles Scott Sherrington published his work on proprioception, interoception, and exteroception – his work forged a new way of thinking about how our body conducts the orchestration of impulses. And it was not just the brain guiding the way to how we functioned on a dynamic level.
If we start backwards, exteroception relates to our common senses of sight, touch, taste, hearing, and the skin itself and how these organs provide information originating outside the body.
Interoception is based on how our internal organs (what is now defined as the enteric nervous system) and the tiny nerve endings called proprioceptors provide movement-based information from our body to our brain. This includes muscles, tendons, and joints—joints and the receptors located within are the most intriguing. Interoception relates to the sensory nerve cells innervating the viscera (thoracic, abdominal and pelvic organs, and the cardiovascular system), their sensory end organs, and the information they convey to the spinal cord and ultimately the brain. (You will learn something really intriguing about this if you keep reading.)
Now let’s define proprioception, as this is a more common term about movement. Proprioception is the ability to sense the position and location and orientation and movement of the body and its parts. It relates to somatic sense, the somatic sensory system, and the faculty of bodily perception. Similar to interoception, this sensory system is associated with the body and includes skin senses and proprioceptors (sensory nerve endings) and the internal organs.
Proprioception has to do with the body’s perception of movement and its spatial orientation of movement from stimuli within the body itself. Think of this as the involuntary aspects of our nervous system perceiving movement from stimuli within our body itself.
A major component of proprioception is the sense of joint position (JPS), which is determined by measuring the accuracy of joint angles. In MELT we call this our GPS system. The joints are like satellites that your brain uses to identify where the joints are located in relationship to the center of gravity and the earth itself.
So what does all of this mean really?
When it comes to proprioception, it’s about sensing the relative position of each body part in relationship to the body’s center of gravity and the ground force gravity itself creates. That sounds complex but try this to see how your proprioception is doing today.
- Sit up tall or stand up.
- Reach one arm over your head with your index finger extended like you are showing someone the number one.
- Close your eyes and then reach your other arm up with your index finger extended and touch the tip of your extended arm.
So what happened? Were you able to meet finger tip to finger tip easily or did you miss it? If you missed it, your proprioceptive capabilities are a little off. Think of proprioception like a GPS system your nervous system uses without your conscious control to acquire your entire body’s global positioning. Seeing your arms and fingers are attached to your body, you would think your nervous system would always be able to find it. Yet that is not necessarily true.
Your nervous system uses proprioceptors and mechanoreceptors (tiny nerve endings) found in abundance in your joints and connective tissue to acquire the GPS signal (in MELT we call this Body Sense). However, if our connective tissue is cellularly dehydrated, our nerve endings aren’t able to signal the brain as to where they are. So by the time you get to those tiny joints in your hand, your brain has veered you off the superhighway and you’ve taken the wrong exit so to speak. Now you are lost. Yet, just like getting off the wrong exit, you somehow figure your way around the roadblocks and mishaps and at some point, get to your ultimate destination. You are just late.
The problem with that is slowly, this inefficiency accumulates and after awhile, you are just plain lost in the woods somewhere with no cell signal and you simply can’t get to where you want to be—not to mention out of gas and frustrated. Make sense?
So what is the interoception part and why is this suddenly become a buzz word in wellness and fitness? First, interoception and exteroception are more complex elements of stability and movement management on a lot of levels. Some people use interoception and proprioception interchangeably and really, I wouldn’t because interoception has a lot to do with our enteric nervous system or gut system.
Like I stated above, interoception as it was originally defined by Charles Sherrington in 1906 encompassed just visceral sensations. But now the term is used to include the physiologic conditions of the entire body and the ability of viscera’s afferent information to reach our mental awareness and affect behavior, either directly or indirectly.
For those of you who don’t know what afferent means, it’s basically information that goes toward our brain from our body. This is in contrast to efferentinformation, which goes from the brain to the body. The system of interoception as a whole constitutes “the material me” and relates to how we perceive feelings from our bodies that determine our mood, sense of well-being, and emotions. Interoception is more frequently relevant to branches of internal medicine as well as psychology and psychiatry however, in my years in practice, when I chat with either of these fields, many have never even heard of the term. Clearly this is a field of great relevance to many areas of medicine, to all branches of “internal medicine” as well medical psychology and possibly some branches of psychiatry.
How this all relates to MELT
So in a nutshell, proprioception is about the body’s relative position as we move. Interoception is how we perceive pain, hunger, and movement of the internal organs yet most of this sense or perception is unconscious to a great degree.
For example, having a “gut feeling” about something could be considered interoception or having butterflies in your belly when you are in love, or even sensing the urge to pee or feeling nervous before speaking in front of an audience. You don’t “think” these things into existence. Your body produces these sensations to get your attention.
Then again, there is exteroception, which has a great deal to do with how we perceive the outside world – not just how our body takes the information in – it’s how we process that information.
The reason why these terms are frequently missing from our clinical vocabulary is that although we have been aware of the underlying concepts of interoception for decades or even centuries there have been few methods of systematically studying the underlying principles in humans until the advent of functional imaging. Technology is only recently being used to scientifically examine all of these neurolophysiologic functions.
This is why I think MELT has been such a help to people in pain. It is aimed at contributing to our understanding to self-awareness and identifying for ourselves how we really feel and what it feels like when the GPS systems are functioning in an ideal way—or not.
MELT and the self-assessment techniques I developed are a simplified way to explore our body’s inner space, to become familiar with the messages our body shares with us instead of waiting to really feel pain or discomfort, to start having a relationship of care for our body. It heightens our sense of ourselves and the world around us so we aren’t just reacting to everything—rather we are more equipped and prepared for things so we both manage and enjoy life more. It also allows us to have a better relationship with ourselves and those around us.
These topics and ways of studying it give us new direction to draw attention to the importance of perception of homeostatic mechanisms as well as shining light on more philosophical problems like the theories and hypothesis of consciousness and the elements we define as the unconscious. All of it is truly and exquisitely complex but relevant to our well-being on many levels.
Because of people like Sherrington, physiologist and anatomists like myself continue to search and learn about these specialized nerve endings now defined as mechanoreceptors that transmit data from our joint capsules to our brain. The understanding of our connective tissue system and how this system morphs and adapts to tension and compression and contributes to how muscles and muscle spindles respond to muscle length and its speed ultimately contribute to our sense of ourselves and where our arms and legs are—at any given moment.
The more accurate the reception, the more precisely this information is processed and utilized by our brain. The body’s knowledge goes far beyond our own mind. We are, to say the least, the most complex, brilliant creature to live on the planet earth. How delightful it is to continue to learn about it on the cellular level.
I’m looking forward to sharing with you the research studies we are initiating with elite institutions to bring forth more understanding of these concepts as they relate to wellness, overall health, and longevity of a good life!