I wasn’t aware of the complexity involved in “feeling what I’m feeling”, so I’m posting relevant parts of this extensive article.
Knowing a bit about interoception is critical to understanding how a disorder of the connective tissue like EDS can result in altered emotions, mostly anxiety, through biochemical processes.
Interoception is contemporarily defined as the sense of the internal state of the body.
This can be both conscious and non-conscious.
It encompasses the brain’s process of integrating signals relayed from the body into specific subregions—like the brainstem, thalamus, insula, somatosensory, and anterior cingulate cortex—allowing for a nuanced representation of the physiological state of the body
This is important for maintaining homeostatic conditions in the body and, potentially, aiding in self-awareness.
Interoceptive signals are projected to the brain via a diversity of neural pathways that allow for the sensory processing and prediction of internal bodily states.
Misrepresentations of internal states, or a disconnect between the body’s signals and the brain’s interpretation and prediction of those signals, have been suggested to underlie some mental disorders such as
- panic disorder,
- anorexia nervosa,
- bulimia nervosa,
- posttraumatic stress disorder (PTSD),
- obsessive compulsive disorder (OCD),
- autism spectrum disorders,
- somatic symptom disorder, and
- illness anxiety disorder.
Visceroception refers to the perception of bodily signals arising specifically from the viscera: the heart, lungs, stomach, and bladder, along with other internal organs in the trunk of the body.
Interoception encompasses visceral signaling, but more broadly relates to all physiological tissues that relay a signal to the central nervous system about the current state of the body.
Interoceptive signals are transmitted to the brain via multiple pathways including
- the lamina I spinothalamic pathway,
- the classical viscerosensory pathway,
- the vagus nerve and glossopharyngeal nerve,
- chemosensory pathways in the blood, and
- somatosensory pathways from the skin
Interoceptive signals arise from many different physiological systems of the body.
Interoception is sometimes generally referred to as “the perception of internal body states” although there are many interoceptive processes in the body which are not perceived.
Importantly, interoception is made possible through a process of “integrating the information coming from inside the body into the central nervous system.”
This definition… exemplifies the dynamic and widening breadth of interoception as a concept in modern literature.
Facets of interoception
Although interoception as a term has more recently gained increased popularity, different aspects of it have been studied since the 1950s. These include the features of
- sensibility, and
Attention describes the ability to observe sensations within the body, it can be directed voluntarily in a “top down” manner or it can be attracted involuntarily in a “bottom up” manner.
Detection reflects the presence or absence of a conscious report of interoceptive stimuli, like a heartbeat or growling stomach.
Magnitude is the intensity of the stimulus, or how strongly the stimuli is felt.
Discrimination describes the ability to localize interoceptive stimuli in the body to specific organs and differentiate them from other bodily stimuli that also occur,
Accuracy (or sensitivity) refers to how precisely and correctly an individual can monitor specific interoceptive processes.
Self-report is itself multifaceted. It describes the ability to reflect on interoceptive experiences occurring over different periods of time, make judgments about them, and describe them
The term “interoceptive awareness” is also frequently used to encompass any (or all) of the different interoception features that are accessible to conscious self-report.
Multiple neural pathways relay information integral to interoceptive processing from the body to the brain. these include
- the lamina I spinothalamic pathway,
- the visceroceptive pathway, and
- the somatosensory pathway.
The lamina I spinothalamic pathway is commonly known for carrying information to the brain about temperature and pain, but it has been suggested to more broadly relay all information about the homeostatic condition of the body.
The visceroceptive pathway relays information about visceral organs to the brain.
The somatosensory pathway relays information about proprioception and discriminative touch to the brain through different receptors in the skin.
Cortical processing of interoception
The thalamus receives signals from sympathetic and parasympathetic afferents during interoceptive processing.
The insula is critically involved in the processing, integration, and cortical representation of visceral and interoceptive information.
The insula is considered to be a “hub” region because it has an extremely high number of connections with other brain areas, suggesting it may be important for an integration of lower-level physiological information and salience.
The anterior insular cortex (AIC) is involved in the representation of “cognitive feelings” which arise from the moment-to-moment integration of homeostatic information from the body.
These feelings engender self-awareness by creating a sentient being (someone able to feel and perceive) aware of bodily and cognitive processing.
The anterior cingulate cortex (ACC) plays a significant role in motivation and the creation of emotion.
An emotion can be seen as comprising both a feeling and a motivation based on that feeling. According to one view, the “feeling” is represented in the insula, while the “motivation” is represented in the ACC.
Many interoceptive tasks activate the insula and ACC together, specifically tasks that elicit strong aversive feeling states like pain.
The sensory motor cortex provides an alternative pathway for sensing interoceptive stimuli.
Although not following the conventional pathway for interoceptive awareness, skin afferents which project to the primary and secondary somatosensory cortices provide the brain with information regarding bodily information.
This area of the brain is commonly engaged by gastrointestinal distension and nociceptive stimulation, but it likely plays a role in representing other interoceptive sensations as well.
Interoception and emotion
The relationship between interoception and emotional experience is an intimate one.
William James and Carl Lange developed the James-Lange theory of emotion, which states that bodily sensations provide the critical basis for emotional experience.
Ensuing models focusing on the neurobiology of feelings states emphasized that the brain’s mapping of different physiological body states are the critical ingredients for emotional experience and consciousness.
Interoception and mental health
Disturbances of interoception occur prominently and frequently in psychiatric disorders.
These symptom fluctuations are often observed during the most severe expression of dysfunction, and they figure prominently in diagnostic classification of several psychiatric disorders.
A few typical examples are reviewed next.
To keep this reasonably brief, I’ve left out all but the one that piqued my interest in this whole topic.
The broad consensus of studies investigating the link between interoceptive awareness and anxiety disorders is that people with anxiety disorders experience heightened awareness of and accuracy in identifying interoceptive processes.
Functional imaging studies provide evidence that people with anxiety disorders experience heightened interoceptive accuracy, suggested by hyperactivation in the anterior cingulate cortex—a region of the brain associated with interoception—in several different kinds of anxiety disorders.
The insula has been suggested to be abnormal in a large scale study across anxiety disorders in general.
Other studies have found that interoceptive accuracy is increased in these patients, as evidenced by their superior ability in heartbeat detection tasks in comparison to healthy controls.
Research and treatments
Ongoing research in interoception has shown the importance of perturbing interoceptive systems.
This allows researchers the ability to document the effects of non-baseline states, which occur during times of panic or anxiety. It also provides the participant the ability to gauge the intensity of sensations within the body.
Although a universal definition of interoception has not been reached, research on interoception and psychiatric disorders has shown a link between interoceptive processing and mental disorders.
And this is how our acute interoceptive awareness from having EDS affects our mental states through the resultant biochemical states.
You can explore other parts of this long article using links from the outline below.