Explaining your internal sensations

The study of how people experience internal sensations, known as interoception, has long been a challenge for scientists. Interoceptive signals can be unconscious, and even when people are aware of them, they can be difficult to describe. Traditional tests for measuring interoceptive awareness, such as detecting one's own heartbeat, are not only hard to do at rest but can also be biased by prior knowledge.

Researchers like Sahib Khalsa at the Laureate Institute for Brain Research are developing minimally invasive ways to probe interoception safely. Khalsa's team has been working with a capsule that buzzes randomly as it moves through the stomach, and they found that people better at detecting the timing of these vibrations showed stronger EEG responses in the posteromedial cortex, a brain region linked to bodily awareness.

However, it's still debated whether having more or less interoceptive awareness is better. People with conditions like generalized anxiety disorder or irritable bowel syndrome may be overly focused on their internal sensations. Researchers are exploring treatments like cognitive training and vagus nerve stimulation (VNS) to help these individuals manage their overwhelming internal sensations.

Transcutaneous auricular vagus nerve stimulation (taVNS) is a noninvasive method that's gaining attention. It's being tested in over 100 clinical trials for various conditions, including PTSD, sepsis, Alzheimer's, and even acute respiratory distress syndrome in COVID-19 patients. Researchers are also investigating whether taVNS can influence consciousness itself, potentially helping people recovering from comas.

In a recent study, scientists used interoception as a probe for consciousness in 68 coma patients. A machine-learning algorithm was able to identify, with 87% accuracy, which patients had been classified as minimally conscious using other measures. If these initial results are confirmed in larger studies, this method could offer a simpler and cheaper way to assess consciousness in people who can't visibly react to external stimuli.

Despite the unanswered questions surrounding interoceptive experiences, this research is challenging the traditional belief that our minds and bodies are separate. Instead, it implies that our consciousness is more connected to our internal bodily sensations than previously thought, contributing to a more unified understanding of the mind-body relationship.