The insular cortex: your brain’s connected island

Insula Diagram

If you’re not a neurologist or involved in brain research, chances are you haven’t heard of the insular cortex (also known as the insula). But in the neurological community, this area of the brain has garnered plenty of attention. And the more we learn about it, the more we find that it’s deeply involved in much of what makes us human.

Here’s what you should know about the insular cortex:

1: It’s located beneath the surface. Anatomically speaking, the insular cortex is part of the cerebrum, whose rounded, wrinkled surface makes up most of our brain. The cerebrum is divided by deep fissures into distinct lobes; the insula is covered up by three of them, which need to be pulled aside for it to be observed.1,2

2: It’s a hub of brain connections. Though the term “insula” derives from the Latin word for “island,” the insular cortex definitely isn’t isolated from the rest of the brain. It has extensive connections to multiple brain regions, including areas involved in sensation, emotion, cognition, and autonomic functions like heart rate and body temperature. Some of these connections bring information to the insula, while others carry signals from the insula to other areas.

3: It receives sensory information. The insula takes in signals from all of our external senses—vision, hearing, etc.—and it also receives signals from inside our body, relating to everything from blood pressure and oxygen levels to hunger and nausea. This makes the insula a key player for interoception, 3 our brain’s ability to monitor our bodily state.

Two friends hugging

4: It’s connected to social touch. The insular cortex receives signals from specialized nerves that react to affective touch, the slow, pleasant stroking of the skin that humans instinctively use to express affection and comfort to each other. 4 This kind of touch has emotional implications—it reduces stress and helps us feel closer to each other. Which points to a key function of the insula…
.Man smiling

5: It marries sensations to emotions. The insula is where sensory information gains positive or negative emotional impact: We feel happy when we see someone we love, or nervous when we hear a strange sound at night. If the insula is damaged, someone might feel pain, but not experience it as unpleasant.

6: It tries to predict the future. When we have to make a decision, the insular cortex helps us estimate the likelihood of a good or bad outcome. “The insula is involved in integrating the external environment and internal bodily state to generate behaviors pre-consciously,” explains Sean Hagberg, PhD, Clinical Assistant Professor of Neurosurgery at the University of New Mexico, and Vice President of Research at Feelmore Labs. “Our brain is essentially predicting what behavior to engage in, based on the state of our body, the external inputs, and our experience.” As a simple example, you might grab a pan sitting on your stove top, feel the heat of the handle, and let go without thinking about it to avoid being burned. Past experience enables your insular cortex to predict the possibility of getting injured. The insula also helps your brain decide which changes in your environment you need to be consciously aware of (your cat knocking over a vase in the next room), and what can be ignored (the neighbor’s dog barking at the mailman). “That way, we’re able to concentrate on tasks without having to look up every two minutes to see if there’s a stranger walking around our room,” Dr. Hagberg says.

Woman looking in mirror


Our inner mirror

Ongoing research about the insular cortex will likely lead to answers about any number of psychiatric and neurological questions. The insula may play a role in anxiety disorders, addiction, depression, schizophrenia, and autism. Some social scientists study how the insula drives empathy. And perhaps most intriguingly, the insula seems crucial for our ability to perceive ourselves.

“There is a lot of research done supporting the notion that the insula is a core component of our self-awareness,” says Dr. Hagberg. For example, in a famous psychological illusion, researchers cover a volunteer’s hand and put a rubber one in its place. “Both the fake and real hands are stroked with brushes,” says Dr. Hagberg. Next, the rubber hand is suddenly smashed with a hammer. “People react as if their real hand was hit. That’s regulated by the insula.”

 

 


 

 

[1] Source unless otherwise noted: Current Biology 27, R573–R591 https://doi.org/10.1016/j.cub.2017.05.010

[2] American Association of Neurological Surgeons aans.org/Patients/Neurosurgical-Conditions-and-Treatments/Anatomy-of-the-Brain

[3] The Science of Every Day Interoception

[4] What is affective touch .. and why do you need it?