Little Island

Little island at the neural crossroads. With big role for humans, mind-body connection and psychotherapy.

Oldie But Goldie…

Have you heard of the insula, I wonder? The word 'insula' means 'island' in Latin, but it’s also the name of a brain region.

Historically, the insula has been less 'famous' than the amygdala (which, incidentally, means 'almond'), but it’s just as important for emotions. In the therapy world, we don’t often hear much about it. Most of us are familiar with terms like the 'amygdala hijack,' but the insula hasn’t inspired any similarly striking expressions.

It is of course very wrong to classify brain regions as 'good' or 'bad' (but let’s do it anyway). However, the amygdala is more infamous than famous; we focus so much on it because of its role in negative processes like threat conditioning, fear, PTSD, and trauma. The insula, on the other hand, is involved in many of the traits we value most in social cognition and emotional processing, such as empathy, compassion, and emotional awareness.

Even more interestingly still, at least for psychotherapy, the history of the insula is somewhat intertwined with the growing interest in neuroscience that emerged in certain corners of the psychotherapy world about 25 years ago. So, please hear me out.

The Somatic-Marker Hypothesis

It all comes down to Antonio Damasio and his now-classic book Descartes’ Error. In this work, and the research that inspired it, Damasio famously revives the James-Lange theory of emotions and argues that there is no thought without emotion - that all thinking is inevitably and fundamentally colored by some degree of emotion. A modern reader might be tempted to see this book as slightly outdated or its claims as self-evident, but that’s only because it was so influential. Its ideas have permeated the 'Overton window' of our time.

The linchpin of Damasio’s argument is our little island: the insula. With his work, Damasio and his collaborators, have propelled the insula from relative obscurity into the spotlight.

In a nutshell, the somatic marker hypothesis posits that all decision-making is, in fact, influenced by some level of emotion - either conscious or, more often, unconscious (implicit). This happens through what Damasio calls somatic markers. According to this view, anything we see or think about triggers a visceral or somatic experience - whether positive or negative - that he refers to as a marker. These positive or negative sensations then influence our decision-making process, often below the threshold of our awareness.

And he insula is relevant here because it serves as a hub for interoceptive awareness: in other words, it’s through the insula that we feel how our body 'feels.' But more on that a little later. For now, let’s take a look at where the insula is actually located in the brain.

On the Neural Crossroads

In the human brain, the insula is hidden deep within the brain tissue, beneath the cortex, and located in the area where the frontal, parietal, and temporal lobes meet. It is actually a part of the cortex itself, referred to as the insular cortex. Which is, I am guessing, where its name comes from: a little island between the cerebral cortex and other subsortical areas.

I say 'insula,' but technically, it's insulae or insulas, as the insula, like most other subcortical structures, is found in both hemispheres. The insula is divided into the posterior and anterior regions, and while these two work together, they have quite different roles

The insula, due to its location between the cortex and the deeper subcortical structes, is a neural crossroad.

Interoception

Interoception is often referred to as our sixth sense - it’s the ability to feel how our body 'feels,' including the visceral sensations, the 'inside' of the body, so to speak. The insula serves as a hub for interoception and functions as a kind of mind-body center. It has also been called the 'visceral brain,' though I suspect some people might cringe at this term, so let’s better leave that one aside.

Signals from the body are transmitted to the posterior part of the insula, which then remaps them to the anterior insula (the frontal part). From there, neural connections relay this sensory information to cortical areas, bringing it into conscious awareness. Or something like that...

Emotions and Feelings

It turns out, perhaps unsurprisingly given its role in interoception, that insula activity is associated with experiencing feelings and emotions. This often occurs alongside the activation of the anterior cingulate cortex (ACC), but that’s a story for another time. What’s interesting is that this is true not only for feelings and emotions directly linked to somatic experiences, like pain or anxiety, but also for more abstract emotions such as social exclusion, unfairness, and social pain (through the salience of the self).

Empathy

In the therapy world, when we think about empathy, we often think of mirror neurons. But the insula plays a role here too. In fact, just as the insula is involved in feeling my own pain, it is also implicated in me feeling your pain.

Specifically, the insula mediates the affective, but not the sensory, component of pain.

The Insula and the Amygdala

Interestingly, the insula has been compared to the amygdala, with the key difference being that the amygdala is central to the implicit (unconscious) experience of emotion, while the insula plays a crucial role in the conscious or explicit experience of emotions.

Physical and Moral Disgust/Shame

The insula has been found to be involved in feelings of physical disgust. But not only. The insula is also activated when I see your disgust. But then, that is not so surprising given its role in empathy, right?

But here’s an even more fascinating twist: the insula is implicated in feelings of moral disgust. Much like physical and emotional pain, the connection between physical and moral disgust turns out to more than just a metaphor.

Areas of overlapping activation of disgust and indignation, including the insula. Moll, Jorge MD et al The Moral Affiliations of Disgust: A Functional MRI Study. Cognitive and Behavioral Neurology March 2005

And Finally ... the Self

In Descartes' Error, Antonio Damasio recounts the case of a patients who, due to seizures, had their complete sense of the body and interoception removed. The seizures impacted the somatosensory maps in the brain - in other words, the areas that 'link' somatic feelings to perceptions, one of which is, of course, the insula. These patients typically not only lose the sense of what is happening to their body but also the sense of who they are.

However, one such patient had an area that remained intact: the anterior insula. Coincidentally, this patient also preserved an acute sense of self and awareness of what was happening to her, despite not 'feeling' her body, so to speak

And this, amongst other things, has led Damasio to believe that the insula had also a role to play in selfhood...

Alright, alright. I am letting you off now.

I might not have gotten everything right - after all, the brain is incredibly complex, and I am still learning. I guess all I hope to achieve with this piece is to put the insula onto your mind map, especially if you are a therapist or interested in emotional life. Pet it, look after it, become the insula whisperer. And if you happen to dream of a little island tonight, I’ll meet you there 🏝️.

As always, thank you for reading.