Humans' Hidden "Sixth Sense" To Be Mapped Following $14.2 Million Prize – What Is Interoception?

Sight, smell, taste, touch, and hearing – these are the senses we’re probably all familiar with. But we humans may not be limited to just five: some scientists argue for a “sixth sense” – though there are several contenders for what this might be – while others suggest we have way more. One candidate for this elusive extra sense is interoception – and now, researchers at Scripps Research and the Allen Institute have been awarded a $14.2 million prize to investigate it further.

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What is interoception?

Interoception is our sense of the internal state of the body. Are you hungry, sad, desperate for the loo? We know the answers to these questions thanks to interoception. 

It is the process by which the nervous system continuously detects and interprets the body’s physiological signals to keep things running smoothly. Let’s say you’re hungry. An interoceptor – a sensor in a nerve cell – will receive a signal, which is then transmitted to your brain. It is processed in a region called the thalamus, which, in turn, triggers your stomach to rumble. The thalamus then sends the information to the insula to decode it – this is when you start to feel hungry. Now that you’re aware of that fact, you can act on it and find yourself something to eat.

While the five classic senses are external and require specialized sensory organs, interoception operates through a network of neural pathways that monitors, among other things, our circulation, digestion, and immunity. As a result, we are often not conscious of it, hence it has been described as our “hidden sixth sense”.

Dysregulation of interoception can have ramifications for our health: it is implicated in conditions including autoimmune disorders, chronic pain, neurodegeneration, and high blood pressure.

Despite its importance in maintaining our vital functions, interoception has historically been understudied. It is incredibly complex: internal signals can be widespread, overlapping, and difficult to isolate and analyze, while the neurons that carry them cover huge ground in the body and can lack clear anatomical boundaries.

The National Institutes of Health Director’s Transformative Research Award

To help bridge this gap, a collaborative team at Scripps Research and the Allen Institute has received the National Institutes of Health (NIH) Director’s Transformative Research Award to decode interoception.

The team, led by Nobel Prize-winning neuroscientist Ardem Patapoutian, alongside Li Ye of Scripps Research and Bosiljka Tasic from the Allen Institute, will receive $14.2 million in funding over five years. They are tasked with creating the first atlas of this internal sensory system.

“My team is honored that the NIH is supporting the kind of collaborative science needed to study such a complex system,” Patapoutian said in a statement.

“We hope our results will help other scientists ask new questions about how internal organs and the nervous system stay in sync,” added Ye. 

With the NIH’s backing, the team will map how sensory neurons connect to a wide range of internal organs, with the ultimate aim of building a comprehensive, 3D atlas that anatomically and molecularly catalogs these neural pathways.

In doing so, they hope to learn more about body-brain communication, which could inspire new approaches to treating disease.

“Interoception is fundamental to nearly every aspect of health, but it remains a largely unexplored frontier of neuroscience,” said co-investigator Xin Jin. “By creating the first atlas of this system, we aim to lay the foundation for better understanding how the brain keeps the body in balance, how that balance can be disrupted in disease and how we might restore it.”

So watch this space. But in the meantime, did you know a sixth sense may be surprisingly common in animals, too?