What is the interoceptive system and how does it work?
Did you know there are more than five senses? And no, we're not talking about a sense of embarrassment or the paranormal sixth sense that gives its name to the movie starring Bruce Willis. In addition to the five senses we learned about in school (sight, hearing, smell, taste, and touch), which are responsible for connecting us with the world around us, we also have the vestibular system and the proprioceptive system , which give us information about our own bodies.
- The vestibular system is responsible for balance; it informs our brain of our position in space—whether we are up, down, or moving to one side or the other.
- Proprioception informs us of the position in which our body is placed, and is responsible for informing us that we have toes, for example, even though you are reading this article and not looking at them.
When these senses are properly adjusted, if we close our eyes and someone pushes us, the vestibular system will tell us which direction we are falling, and we will compensate for this movement with our limbs. We wouldn't be able to tell which way we are falling using only sight or touch.
But there is another, perhaps less well-known, sense: interoception . This sense comprises all those internal "alarms" that our body emits , such as appetite, thirst, sleepiness or fatigue, the sensation of fever, internal pain, the urge to urinate or defecate, nervousness, or sexual arousal, among others. But how does this sense, to which we don't usually pay much attention, actually work ?
Interoception refers to the ability to perceive and understand the internal signals of our body that indicate sensations such as appetite, thirst, tiredness, pain, the urge to urinate, or nervousness, among others.
Each organ in our body contains sensory receptors for these processes . In the case of appetite , for example, our stomach sends a hunger or satiety signal via nerve fibers that terminate in our brain and hormones that circulate in the bloodstream. It is our brain, specifically the hypothalamus, that interprets this signal; and it is when this information is processed that we say "I'm hungry" or, conversely, "thank you, I'm not hungry anymore." This is an automatic and unconscious process, but it is fundamental for regulating our behavior, because depending on this, we will eat or not. Something similar happens when the interoceptive system sends us a reaction signal to an emotion , such as the sensation of a "lump in the throat," and we must interpret it.
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Interoceptive sense in autistic people
We know that sensory processing in autistic people differs from that of neurotypical people (that's what we call people with typical or non-autistic development). In autistic people, there is a fairly high tendency toward hyporeactivity to interoceptive stimuli, meaning they are less sensitive to these stimuli. What does this mean? Does it mean that an autistic person doesn't feel hunger? No, but they might go many more hours than recommended without eating until the sensation of hunger arises. And the same goes for thirst. Or, for example, they might have to urinate very urgently because the sensation of a full bladder only reaches the brain when it is already very full. Another way in which hyporeactivity to interoceptive sensory stimuli can manifest is in the difficulty of identifying an internal signal : the person feels that something is wrong with their body, but is it because they are thirsty? Tired? Nervous? In pain? Feverish?
Autistic people are often less sensitive to these stimuli. They may go hours without eating or drinking; they may not feel the urge to urinate until their bladder is very full; or they may have difficulty interpreting signals such as tiredness or nervousness.
What happens if we don't properly detect these signals? Well , we won't regulate our behavior effectively, or perhaps we won't identify our emotions correctly , and therefore won't regulate them well either. In other words, because we don't realize we've gone hours without drinking water and are becoming dehydrated, we don't take the necessary steps to drink and restore our body's balance. Or, for example, if we have trouble recognizing the signs of fatigue, we might not give our bodies the rest they need.
Strategies for sensory self-regulation in autistic people
In the case of recognizing our emotions, the process is even more complex, since we receive similar or identical signals from our body in completely different situations, and we have to know how to interpret them according to the context or our previous experiences. That is, we can notice our heartbeat signal both when we are nervous during an exam and when we are happy and excited about a trip we are about to take.
We know that, as with everything, there are differences and individual characteristics among people. And, just as some people have a more or less acute sense of smell, others have a more or less refined sense of interoception. It's important to have this information so we can find strategies (setting alarms, taking breaks to drink or urinate, having a well-established routine, using a visual calendar, keeping a brief record of our internal state, etc.) that can help us, and those close to us, to regulate these internal sensations and live as healthy a life as possible.
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