What is interoception?

What is interoception?

Interoception is the sense of the body from the inside. The neuroscientist A. D. Craig defined it in 2002 as the sense of the physiological condition of the entire body, and that definition has held: it covers everything the brain learns about how the body is doing, as opposed to what the eyes, ears and skin report about the world outside.

• Heart and blood vessels: heartbeat, pounding, pressure, flushing.
• Breathing: air hunger, tightness, the urge to sigh.
• Gut: fullness, nausea, cramping, urgency.
• Temperature: warmth, chill, the sense of a fever coming on.
• Hunger, thirst and fatigue.
• Muscles and joints: effort, tension, stiffness, ache.
• Pain and itch, which Craig grouped with the others as feelings about the body's condition rather than as a separate sense.

A useful way to picture this is a newsroom. Every organ is a reporter filing copy all day: the stomach files a note on fullness, the lungs on how much air is moving, the lower back on load and posture. Thousands of reports arrive every hour. The brain is the news director, and its job is to decide which few stories make the front page, which get a small mention on page twelve, and which never run at all. What you consciously feel is the morning edition, not the wire feed.

Most of this editing happens below awareness and most of it is sensible. You do not need to know your blood pressure moment to moment. You do need to know when your bladder is full. The problem in chronic pain is not that the newsroom exists; the problem is that the editorial line can drift.

How does the brain process interoceptive signals?

Internal signals travel from the body through the spinal cord and brainstem to the thalamus and then to the insula, with the anterior cingulate cortex adding the push to do something about them. That is the anatomical path. The more recent idea is that the brain is predicting those signals before they arrive.

The pathway

Craig's 2002 review traced a dedicated route: small-diameter nerve fibers carrying information about tissue state feed a spinal pathway that runs through the brainstem to the thalamus and on to the posterior insula, which he proposed as the primary interoceptive cortex. The signal is then re-represented in the anterior insula, where it becomes something you can feel, and linked to the anterior cingulate cortex, which attaches motivation to it: the urge to shift position, slow down, eat, or protect. In this account, pain, temperature and itch are homeostatic feelings in the same family as hunger and breathlessness.

Interoceptive inference

In 2013 Anil Seth proposed that the brain handles these signals the way the predictive coding framework says it handles everything: it maintains a model of what the body's state should be, predicts the incoming signals, and uses the mismatch between prediction and signal to correct the model. The feeling you have of your body is the brain's best current guess, not a direct readout. This is a framework with growing but incomplete evidence, and some of its specific claims are still being tested.

In newsroom terms, the news director does not wait for the reporters. The front page for tomorrow is drafted tonight based on what usually happens, and the morning reports are used to edit the draft. A report that matches the draft barely registers. A report that contradicts it gets attention, if the editor trusts the reporter. How much the editor trusts the draft versus the reporter is what the framework calls precision, and it turns out to be the lever that attention, mood and past experience all pull on.

What is interoceptive awareness, and can you have too much or too little?

Interoceptive awareness is a loose everyday phrase for how in touch someone is with their body. Research has split it into at least three measurable things, and they do not move together.

Garfinkel and colleagues, who proposed this three-part model in 2015, found that the dimensions were only weakly related. Someone can score high on sensibility, reporting that they are highly tuned in to their body, and still perform poorly on accuracy. This is the finding that matters most for chronic pain.

Hypervigilance is not awareness

A person who scans their body all day, catches every twinge and reads each one as a sign of trouble has very high sensibility. They are rarely more accurate. In the newsroom, this is a desk that treats every wire report as breaking news and runs it on the front page. The paper is not better informed for it; it is louder and less reliable, and its readers are frightened. Good interoception is a matter of how you attend, not how much: noticing a sensation, placing it correctly, and letting it be the size it actually is.

Too little attention has costs as well. People who have learned to tune the body out, often because attending to it was painful or frightening, can miss signals that would help them pace, rest or eat. The target in retraining is neither more nor less, but a calmer and more accurate editor.

How does interoception go wrong in chronic pain?

In chronic pain the brain's internal model learns to expect threat from the body. Once that expectation is strong enough, ordinary signals are more likely to be felt as pain, and the body's response to feeling pain produces new signals that confirm the expectation.

Van den Bergh and colleagues laid out the mechanism in 2017. When the brain holds a strong prior expectation about the body and the incoming signal is ambiguous, weak or noisy, the experience that results tracks the expectation more than the signal. They called this taking the inferential leap, and they argued it helps explain why physical symptoms can persist, spread and fluctuate in ways that do not follow the tissue. The signals are still real. The leap is in what they come to mean.

A minor ache as front-page news

Consider someone three years into back pain. They lean over to load the dishwasher and feel a pull, the kind of small muscular report that a back without a history would file and the editor would spike. This newsroom has learned that back stories are the only stories that matter, so the report runs as a headline. The person stiffens, holds their breath, and their heart rate climbs. Each of those is a new report filed back to the same newsroom, and each one reads as further evidence that the headline was right.

1. A sensation arrives that is ambiguous on its own.
2. A threat-weighted model interprets it as danger, and it is felt as pain or as a warning of pain.
3. The body braces: muscles guard, breathing shallows, the stress response rises.
4. Bracing generates fresh interoceptive signals, tension, racing heart, nausea, which are read through the same threat-weighted model.
5. The model is confirmed and the threshold for the next headline drops a little further.

Khalsa and colleagues' 2018 roadmap on interoception and mental health placed altered interoceptive processing at the center of a research agenda spanning anxiety, depression, eating disorders, addiction and somatic symptom and pain conditions. The paper is explicit that much of this is proposed rather than proven, and that the measurement tools are still immature. It is a map of open questions as much as a set of findings.

The conditions where this lens fits most naturally are the ones in which the main complaint is itself an internal signal. In irritable bowel syndrome, ordinary gut sensations are felt as pain and urgency. In fibromyalgia, muscle and joint signals from across the body are read as painful, alongside fatigue and poor sleep. Both overlap with what the central sensitization literature describes from the spinal cord upward, and with the broader pattern of nervous system dysregulation that keeps the stress response running.

People in this state often describe living with a constant weather report from inside: a sense that something is always brewing, even on quiet days. In this newsroom the weather page carries a storm warning every morning. The forecast is real in the sense that the editor really has issued it. Whether a storm is coming is a separate question, and one that needs medical assessment, since tissue, nerves and disease are real inputs that a threat-weighted editor can also be reporting on correctly.

How does interoception shape the sense of self?

The most basic feeling of being a self, of being somebody located in a body, is built in large part from interoception. If the body is read as unsafe for long enough, the self that is built from that reading changes too.

Seth's 2013 paper went further than describing how the brain processes body signals. It argued that the experience of being an embodied self is itself interoceptive inference: the brain's running prediction of its own physiological state is what gives rise to the sense that there is a stable someone here, in this body, right now. Emotions, in this view, are the brain's interpretations of predicted bodily states. The argument is theoretical and contested in its details, but it has become one of the main accounts of how a sense of self is constructed rather than given.

This is the thread that runs through the whole therapeutic neuroscience series: our sense of self is constructed, and chronic pain builds a different self. If the newsroom has run threat headlines about the body for ten years, its readers come to believe they live in a dangerous place. The self is the reader. A person whose body has been reported as fragile, unpredictable and unsafe, day after day, ends up with a self organized around those reports: cautious, braced, watching for the next story. That self is a reasonable response to the edition it has been handed every morning, and nothing like a character flaw.

It also explains why pain retraining so often changes how people feel about themselves before it changes how much pain they report. When the interoceptive reading shifts toward safety, the self built from it begins to shift as well, and confidence and willingness to move tend to return first.

How is interoception retrained?

By changing how signals are attended to and what they come to predict, rather than by ignoring them. Several methods do this, and each works on a different part of the editing process.

Somatic tracking

Somatic tracking is the attention practice at the center of pain reprocessing therapy. The person turns toward a sensation with curiosity, describes it in plain physical terms, and repeatedly reminds the brain that it is safe. What it changes is the meaning attached to the signal: the threat weighting drops, and the signal is given a chance to be felt at its actual size. In newsroom terms, it is the editor re-reading a report slowly instead of reaching for the headline font.

Interoceptive exposure

Interoceptive exposure comes from the treatment of panic disorder, where people deliberately bring on harmless sensations, a racing heart from stair climbing or dizziness from spinning, so the brain can learn that the sensation is survivable and does not lead to catastrophe. Applied to chronic pain, it means approaching the sensations a person has been bracing against, in controlled doses, and staying with them while the predicted disaster fails to arrive. What it changes is the prediction that a sensation leads to harm.

Body awareness practices

Breath-focused practice, body scans and mindfulness-based approaches train the editor to notice without alarm. Research suggests they can shift self-reported body awareness and reduce distress about symptoms, with effects on pain itself that are generally modest and variable. Their contribution is a steadier, more accurate attention rather than a direct effect on pain.

Graded movement

Movement produces interoceptive reports of its own: effort, warmth, a faster heartbeat, muscle fatigue. In someone with fear of movement, those reports have been filed under danger. Graded exposure to movement, built up in tolerable steps, lets the brain receive the full set of movement signals and then observe that nothing bad follows. The spinal and brainstem signals keep arriving; what changes is the prior they are read against.

Virtual embodiment

Karuna Virtual Embodiment Training (KVET)™ is a 12-week program done at home with a provided headset: short daily VR sessions, a weekly one-on-one session with a pain coach, and clinician review before the program starts with oversight throughout. The VR exercises are designed to create safe prediction errors around movement and to retrain the brain's map of the body, so that the newsroom receives first-person evidence, repeated over weeks, that the body moves and is not harmed. The reasoning behind this is covered on our virtual embodiment therapy page and in our commentary on virtual embodiment and pain. Many people improve substantially and some do not; the outcome data Karuna has collected, with its limits spelled out, is on the how it works page.

None of these methods tries to silence the reporters. The aim is to retrain the editor so that an accurate report gets accurate coverage, and so that the front page is no longer written before the news arrives.

What does this mean for someone with chronic pain?

It means the sensations you feel are real, the interpretation of them is adjustable, and adjusting it takes repetition rather than insight alone. Knowing that the brain edits body signals does not by itself change the edit. Practicing a different way of attending, many times, over weeks, does.

• Notice rather than scan. Checking the body for trouble is a different act from feeling it. If you catch yourself scanning, that is useful information about the editor, not about the back.
• Describe sensations plainly. Warm, tight, pulling, heavy. Plain description gives the brain a less threatening category to file the report under.
• Move within tolerance and then a little beyond it. Movement that produces effort and a faster heartbeat without harm is some of the most persuasive evidence the brain can receive.
• Expect flares. A flare during retraining is a return of the old headline, not proof that the headline was right. Having a plan for them is part of the work.
• Work with someone who knows chronic pain. Too little exposure keeps the prediction intact, and too much teaches the brain the wrong lesson. The dose matters.

For clinicians, the practical implication is to ask about hypervigilance and body scanning as a separate thing from pain intensity, to be careful not to confuse a patient's high interoceptive sensibility with good body awareness, and to keep saying, in plain words, that the pain is real. A patient who hears that their interoception is involved and concludes they have been told it is all in their head will, understandably, stop listening.

If you want to talk through whether this approach fits your pain, Karuna offers a free consultation, and a clinician reviews every case before the program begins.