Bodymaps pt 4: interoception, attention and the heart.

So, where were we? Let’s review a couple of points:

– The entire body is “mapped” topographically in various areas in the brain. The best known of these areas are the somatosensory cortex and the motor cortex, but there are many others, some of which I’ll be introducing in this post. The “feelings” we have in our bodies correspond to activity in groups of neurons in these parts of the brain: stroke your left foot and neurons in the “left foot” areas will activate, imagine your left foot being stroked and the same neurons will activate, and (importantly) direct stimulation of the “left foot” areas of the somatosensory cortex will feel the same as your left foot being touched (there are different types of sensation which could be stimulated, like heat or pressure or stabbing, but we don’t need to get into that just yet).


– The take home message is that all sensation happens in the brain: if the foot is touched and sensory neurons in the extremities respond, spinal reflexes and other systems all the way into the brainstem and midbrain can be activated but if the signal does not reach the cortex you won’t feel a thing. Even reaching the cortex doesn’t guarantee that any given sensory signal will be consciously felt, since in any given moment the cortex is receiving a ridiculous number of signals from every sensory modality and only a few of them are strong enough to have a chance of entering our normal awareness.

All of these “bodymaps” are plastic: they are constantly changing and being updated in response to stimuli. If you spend time carefully stimulating every part of the skin of your right hand and moving all of the fingers, palm and wrist in every possible direction paying close attention to how it all feels, the “maps” in your brain representing your right hand will become more detailed (neurons will become more sensitive to smaller stimuli, they will form more synapses with each other, nerve transmission speed will increase, etc), you will feel more and what you do feel will be more accurate. If you injure your right hand and put all of the fingers and wrist in a cast so that they can’t move for months on end, those same maps will degenerate and you’ll feel much less. Thus, it is possible to feel one’s own body in ever-greater detail through appropriate practice.


Most of the various Eastern physical-spiritual traditions (and various others, old and new) involve a systematic exploration of all of the positions and movements of the various bones, muscles and joints of the body through “exercise” and of all of the more subtle sensations of the same areas and throughout the entire body through “meditation”. Those same traditions all place particular emphasis on breathing and drawing the attention into (and thus progressively increasing awareness of) the spine and the deep central axis of the body from the perineum at the base of the pelvic floor to the center of the skull.

I think that pretty much brings us up to speed, so now we can get into the really interesting stuff: interoception – feeling inside the body.

So what happens when we try to feel inside our bodies? Firstly, it’s often very difficult. Our brains and nervous systems are actually much more inclined to notice what’s going on outside: sounds, visual stimuli, smells, people (“what’s that? is it dangerous? can I eat it? can I have sex with it?) and so on. We usually don’t notice what’s taking place inside our bodies except for when they are uncomfortable: when we’re hungry, when we’re in pain, we’re hot, tired, or when we’re really exerting ourselves. Of course all of this makes evolutionary sense since most immediate dangers and rewards necessary for survival are outside, and maintenance of physiological processes needs to go on constantly twenty four hours a day and thus it would be far too tiring and complicated for us if we had to consciously monitor and regulate every breath and every heartbeat and every squeeze of partially digested food through our intestines. Nonetheless we do have sensory nerve endings distributed throughout the insides of our bodies that are transmitting information about the various tissues and organs in which they are embedded, all the time – we just don’t usually notice. Just as there are sensory nerves active in the little toe of your left foot right now, transmitting sensory information through your spinal cord to your brain, but you didn’t notice them because your attention was somewhere else (engrossed in reading my amazing blog – fascinating!)

Attention acts as a filter. The central nervous system is receiving a mind-bogglingly huge amount of information from the periphery constantly, and has to decide which streams of information deserve priority in any given moment, effectively turning up the volume and resolution on those streams and inhibiting the signals from all of the other streams. The slight tingling sensation in your little toe (which you’d no doubt forgotten about again) generally rates as “low priority” whenever just about anything else is going on, and the same is true for the sensations coming from activities inside the body. In order to clearly feel inside the body the attention must be trained so that it is strong enough to amplify the more subtle signals coming from inside while filtering out or inhibiting signals from the other senses.

Another reason we don’t feel as much from inside the body is that those sensory pathways which deal with the interior of the body are less myelinated and thus their signals are much slower and less distinct. These pathways are evolutionarily much older, the more recent pathways from the skin, muscles and joints have a well-myelinated “fast track” through the spinal cord to the cortex and so we are much more inclined to notice information coming in from them – even the little toe.

For the few people who would like to learn about such things in depth, here is one of Dr Najeeb’s excellent medical science lectures on “ascending tracts in the central nervous system”. I’m always (foolishly?) hoping that one or two other serious students of Yoga or Daoist alchemy, “Kundalini” practices etc will realize that our nervous system is where all the action is, and will start putting in some time and effort and giving it the attention it deserves.

Ok so that’s all a bunch of reasons why we’re not particularly aware of this thing called “interoception” – it’s not really that useful for getting things done out there in the world (actually it can be extremely useful, and it turns out that it’s absolutely essential for certain extremely important things, but more on that later) – but what actually happens when we DO feel what’s going on inside our bodies, what is it that we feel?

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Blood flow. By far the biggest, strongest, most noticeable activity taking place inside the body is the beating of the heart. A huge ball of muscle, contracting strongly approximately once every second, pumping all of the blood in your body (about 5 litres) through your whole system every minute, causing every artery, vein and capillary in your entire body to pulsate rhythmically with every beat. Every second of every day.

Changes of pressure in the arteries. As blood surges through the system, the elastic walls of the arteries are stretched, so a wave of pressure moves from the heart towards the periphery, spiralling through the arch of the aorta, out through the neck into the head, through the armpits to the arms, through the stomach and down through the groin down to the legs and feet. The pulse, which can be felt by placing the fingers on any of several areas where the arteries pass close to the surface of the body, can be felt throughout the body simply by placing the attention wherever there is an artery and “tuning in” – using the power of selective attention to “focus” on the area and inhibit or “tune out” other competing signals.

With a bit of practice, it is possible to experience the entire body as a pulsating mass of of fluid-filled tubes, beating in time with the heart.

Well, these posts always seem to take longer, and contain more information, than I expect at first. I’ll leave this one here for now, and in my next post I’ll start on the actual method used in every tradition to develop the interoceptive sense: the breath!

In the meantime, for those who don’t mind a bit of serious science talk by serious scientists, this video by neuroanatomist Bud Craig is REALLY interesting:

Bodymaps, spinal awareness and interoception.

Ok then what’s next?

So far I’ve outlined the concept of “bodymaps” or “homonculi”, topographical representations of the body in the brain. How they are dynamic and constantly being updated according to our experience and the demands placed on them by our daily activities. How our abilities to sense and feel our bodies develop (or fail to develop) in the same way as our motor patterns and all other cognitive skills – “use it or lose it” is the name of the game.

I’ve briefly discussed “sensorimotor amnesia” and how various traditions and methods of physical culture can be understood as ways of recovering and improving our sense of our own bodies.

Anyone who explores eastern traditions like Yoga, Buddhism and Daoism in any depth – enough to go beyond the early infatuation with magical powers and instant enlightenment – will discover that these traditions are all based primarily on a careful and systematic observation of nature, starting with one’s own body, undertaken by each individual over many thousands of minutes and hours. Attainment of “total knowledge of mind and body” is a commonly stated goal. Relief from suffering, clarity and peace of mind, ease of body, improved sensitivity and intuition, and boundless compassion for all things are generally considered to be the fruits of the practice.

So far I’ve mostly talked about various methods of “waking up” the outsides of the body: the skin, muscles and joints of the limbs, trunk, face, etc. Now let’s take things slightly deeper and talk a bit more about exploring the spine and the body’s central axis.

Pictures like the one above are relatively common in certain traditions of Daoist “internal alchemy”, often related to a practice known as the “small heavenly cycle” or “microcosmic orbit” (and it’s extension the “big heavenly cycle” or “macrocosmic orbit”). Obviously the anatomy is far from exact, but the point to remember is that they are pictorial representations of subjective experiences.

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But what are the practices represented by these pictures? A common explanation goes something like “circulating energy through meridians, which opens these meridians and strengthens the flow of energy” which then improves health and longevity, develops spiritual and psychic powers and eventually immortality.

Let’s look closer at what a practitioner of such methods is actually doing.

– Usually some sort of movement practice which takes the spine through it’s whole range of motion, often involving wave-like undulations through each vertebral segment and/or movements of the hands and arms. Maybe even something like this:

– A still, seated or standing, meditation practice in which the attention is focused on different segments of the spine individually, on corresponding areas on the front of the body, and on whatever can be felt taking place internally between these two points. Often, this stage will involve a breathing practice in which specific muscular contractions change the pressure and blood flow in different parts of the torso, helping awareness to penetrate into areas which might otherwise be hidden.

– A practice of “cycling” the awareness/attention along the spine and the front of the body, often combined in various ways with specific methods of inhalation and exhalation.

First result of a youtube search:

Now I’m NOT advocating following and practicing the methods described by Mantak Chia in his many books. The video is just an example of the kind of stuff people do, and the kinds of words they use to describe it.

The problem with the traditional explanations is that all too often – unless the person explaining is very good, experienced in the practice and capable of translating to a modern audience – they fall apart when you question them: what evidence is there that surplus “spirit energy” is stored behind the knee? What is “spirit energy” in the first place?

The answer can basically be whatever the person feels like saying, or whatever they believe, and the evidence is limited to “because I say so”, “because I believe so” or “because some ancient people said so”.

I am actually completely fascinated by that last one. I am certainly not of the opinion that the beliefs of ancient people or other cultures should be dismissed and forgotten. I am also not going to start taking the usual “skeptics” argument of “qi doesn’t exist, all of this stuff is superstitious nonsense and there is no point bothering to examine it at all”.

What I am going to do is take a look at some of the effects of such practices which are entirely supported by current science.

Firstly: all of the above are practices of cultivating awareness and focused attention. The movement practices like spinal undulations and so on all help to direct the attention into and thus improve awareness of the parts being moved.

Secondly: the focused attention practices performed in the seated or standing postures, without external movement, will improve awareness of more subtle changes taking place in the parts of the body being focused on, according to the Weber-Fechner principle. It is easier to feel more by moving the areas because larger changes are taking place, while the body is still these areas can still be felt but the changes taking place there are generally of a much smaller magnitude. Remember, the nervous system’s job is to sense and respond to change so we can see straight away that such practices of cultivating awareness and attention (i.e. of noticing what is happening) are forms of training for the brain and nervous system.

Thirdly: combining awareness of the spine and corresponding areas on the front of the body with awareness of breathing will tend to draw the awareness inside the body, developing a greater sensitivity to of the workings of the autonomic nervous system (ANS), the parts of the nervous system responsible for regulating unconscious functions like heart rate, blood pressure, and breathing.

Here’s a diagram of the ANS:


As we can see from the diagram, the ANS is responsible for regulating the activities of the different internal organs present at different levels of the spinal column. Its effects can be seen (and felt) in the eyes, facial muscles, salivary glands, the heart and lungs, blood vessels throughout the body, the digestive and excretory organs. The ANS has two basic settings with only two possible effects: it can either increase or decrease the activity in the organs over which it has influence.

Just for comparison, here’s a fairly standard picture of the “Chakra system”, from a quick google search. Maybe see if you can do some “neuro-anthropological translation” of the image for yourself, keeping in mind once again that it is a pictorial representation of someone’s subjective experience:


To summarize what we’ve established so far. Whatever else they may do (“qi flow”, psychic powers, etc), some things which practices like the Daoist “small heavenly cycle” and equivalent practices in Yogic and Buddhist traditions (or any other traditions) emphasising the spine and central axis most definitely do do are:

– Improve attention and awareness of the spine so as to gradually develop a complete “map” of the spine and related areas in the somatosensory and motor areas of the cerebral cortex, “filling in” areas which would otherwise be forgotten or vague and unfamiliar. Using methods like this it is entirely possible to develop complete and distinct awareness and control of the position and motion of each and every spinal vertebra.

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– Improve spinal mobility through every segment, where otherwise there would be areas which are stiff and fixed, forcing potentially excessive movement into other more mobile segments. Seven cervical vertebrae, twelve thoracic, five lumbar, five vertebrae fused into the sacrum and three fused into the coccyx. Each segment capable of differing degrees of flexion, extension, lateral flexion and rotation.

Gradually direct attention and awareness inside the body, improving awareness of changes in internal blood flow and other autonomic processes at different levels of the spine and their relationships with the mind, the emotions, and the breath.

Awareness of the internal processes is known as “interoception”, and involves another separate part of the brain buried deep beneath the somatosensory and motor areas known as the “insula”, where there are maps of the internal organs and which recent research suggests is one of the primary areas responsible for self-awareness, emotions, and empathy.

This is where things start to get really interesting, and where a lot of these practices from the Daoist, Yogic, Buddhist and Tantric traditions really start to make sense.