The Significance of InteroceptionBottom-up vs Top-down Communications in the Body

Introduction

Our brain continuously receives signals from the body and the environment. The process by which we identify signals from the body such as ‘I am hungry, I feel afraid, it made my skin crawl’ is referred to as interoception while, signals from outside the body are transmitted by exteroception. Although we are mostly unaware of internal bodily processes, such as our heartbeats, they can impact our perception, cognition and emotions. This article’s focus is on interoception, as it relates to our internal organs and skin. It represents a bottom-up approach and therefore, it flies in the face of horse and buggy neuroscience with its exclusive interest in top-down signaling systems.

As we shall see the lungs and respiration, the gut and its peristaltic movements, and even the skin play a surprisingly important role in determining our cognition, emotions and health. They link our physical and psychological experiences.

Most of us do not realize it but our visceral organs maintain a consistent, steady, rhythmic pace. Heartbeats (I have written previously on this subject), breaths and gut contractions repeat themselves with regularity, keeping the body in a physiological equilibrium known as homeostasis. Each of these cycles sends chemical and electrical signals to the brain by way of the vagus nerve and the blood circulation. Thus, specific regions of the central nervous system synchronize with activities in these visceral organs, with results described below.

The Lungs

Many mindfulness and meditation techniques focus on proper breathing as a path to relaxation, self-awareness and health. Contrary to other bodily signals, breaths are easily accessible to consciousness and are partially amenable to voluntary control. Alessandro Morti is a research fellow at the Social and Cognitive Neuroscience Laboratory at the University of Rome who introduced the term embreathment to

highlight the role of breathing in corporeal (body) awareness. Monti suggests that breathing is almost as important as visual appearance for fostering body ownership and more important than any other cue for body agency.

People suffering from panic disorder, anxiety, depression or depersonalization may benefit from learning to use regular breathing techniques.

The Gut

I have already pointed out the importance the gut microbiome plays in health and disease. Here I want to bring to your attention the work of Jane Aspell at Anglia Ruskin University (ARU) who lead a study on gut-brain signaling. Her team measured the strength of the connection between the gut and the brain by recording the electrical activity of both regions at the same time.

The study is the first to investigate, and first to identify, the association between body image and the brain's processing of internal signals that occur unconsciously.

Carried out by a team of psychologists and neuroscientists at Anglia Ruskin University (ARU), the study found that adults whose brains are less efficient at detecting these internal messages are more likely to experience body shame and weight preoccupation.

This research could have therapeutic implications for people suffering with conditions in which body image plays a significant role. For example, the unconscious signals could be made conscious. Further research could even be applied to the clinic as it may be the case that brain responses to gut signals could indicate a predisposition to eating disorders.

The Skin

There are times in life when you suddenly feel very happy and you literally experience a running down your spine and arms. At other times, when you are particularly horrified you may recall the event by saying, “It made my skin crawl.” On the other hand, peak emotional experiences during exposure to emotionally meaningful songs, speeches or art pieces will universally produce what scientists refer to as aesthetic chills, or frisson. Like nausea, disgust, sudden loss of bladder or bowel control, they are expressions of embodied feelings. This skin reaction, chills, ‘made the hair on my back stand up,’ is a remarkable embodied feeling (a somatic marker) which is tied to this abstract emotion (meaningful moment).

Felix Schoeller at the Centre for Research and Interdisciplinarity in Paris and Alessandro Monti at the University of Rome have shown that the frisson device they invented can reliably induce chills in participants and elicit feelings of pleasure and empathy. Their results suggest that emotion prosthetics and somatosensory interfaces may provide novel, non-invasive tools for intervention on higher cognitive functioning through controlled stimulation of body signals, for instance in mood disorders.

Facial Expression

Researchers from the University of Wuerzburg and Georgia investigated the hypothesis that people's facial activity influences their affective responses. Subjects were required to hold a pen in their teeth, which unobtrusively creates a contraction of the zygomaticus major muscles, the muscles involved in the production of a human smile. Study participants in the pen-in-teeth condition rated humorous cartoons as being funnier than subjects in the control condition in which zygomaticus contractions were inhibited.

Experiments by Randy J Larsen at Washington University in St. Louis, represent an extension of Larsen’s studies by investigating the facial feedback of unpleasant emotions. What they did was to attach two golf tees to their group of volunteers’ brow region (just above the inside comer of each eye) and then instructing them to touch the tips of the golf tees together as part of a "divided-attention" experiment. Touching the tips of the golf tees together could only be achieved by a contraction of the corrugator supercilii muscles, the muscles involved in the production of a sad emotional facial expression. Subjects reported significantly more sadness in response to aversive photographs while touching the tips of the golf tees together than under conditions which inhibited corrugator contractions. These results corroborate Larsens’s findings that facial feedback affects a person’s emotions both, positive and negative.

Final Thoughts

When we think about ourselves, we tend to rely on input from our environment mainly through our eyes and ears sometimes smell but neglect input from within our

bodies. Yet signals from within play a significant role in everything we do.

Key Takeaways

 Although we are mostly unaware of internal bodily processes, such as our breathing, they can affect our perception, cognition and emotions.

 Tools such as the frisson device help us understand links between interoception (our sense of our body's internal state) and the interoception-related disorders like addiction, somatic sensation disorders, and anxiety.

 Experimental results directly support theories anchoring selfhood to interoceptive signals originating from internal organs.

 Muscle contractions in the face influence subjective emotional experience.

References

Schoeller, F., & Perlovsky, L. (2016). Aesthetic chills: Knowledge-acquisition, meaning-making, and aesthetic emotions. Frontiers in psychology, 7, 1093.

Monti, A., Porciello, G., Tieri, G., & Aglioti, S. M. (2020). The “embreathment” illusion highlights the role of breathing in corporeal awareness. Journal of Neurophysiology.

Todd, J., Cardellicchio, P., Swami, V., Cardini, F., & Aspell, J. E. (2021). Weaker implicit interoception is associated with more negative body image: Evidence from gastric-alpha phase amplitude coupling and the heartbeat evoked potential. Cortex.

Strack, F., Martin, L. L., & Stepper, S. (1988). Inhibiting and facilitating conditions of the human smile: a nonobtrusive test of the facial feedback hypothesis. Journal of personality and social psychology, 54(5), 768.

Larsen, R. J., Kasimatis, M., & Frey, K. (1992). Facilitating the furrowed brow: An unobtrusive test of the facial feedback hypothesis applied to unpleasant affect. Cognition and Emotion, 6(5), 321-338.