Often popular books on the brain will tell you that a particular part of the brain is responsible for various human attributes, but there is no common thread that jumps out at you. You learn more about people reading a good novel than you do after reading 100 pages of bewildering functions of grey matter..
The Insula (see diagram below) is an example. I’ll list a few tantalizing conclusions from various studies, and if you find a common thread, add a comment and let me know.
According to neuroscientists who study it, the insula is crucial to understanding what it feels like to be human.
They say it is the wellspring of social emotions, things like lust and disgust, pride and humiliation, guilt and atonement. It helps give rise to moral intuition, empathy and the capacity to respond emotionally to music.
So here are a few findings on this part of the brain:
- A conservative or left-wing brain? – liberals have higher insula activation:
Researchers have long wondered if some people can’t help but be an extreme left-winger or right-winger, based on innate biology. To an extent, studies of the brains of self-identified liberals and conservatives have yielded some consistent trends.Two of these trends are that liberals tend to have more the insula and anterior cingulate cortex. Among other functions, the two regions overlap to an extent by dealing with cognitive conflict, in the insula’s case, while the anterior cingulate cortex helps in processing conflicting information.Conservatives, on the other hand, have demonstrated more activity in the amygdala, known as the brain’s “fear center.” “If you see a snake or a picture of a snake, the amygdala will light up.
- Higher insula activation when thinking about risk is associated with criminality. In fact criminals think about risk in an opposite way to law-abiding citizens:
A study has shown a distinction between how risk is cognitively processed by law-abiding citizens and how that differs from lawbreakers, allowing researchers to better understand the criminal mind.“We have found that criminal behavior is associated with a particular kind of thinking about risk,” said Valerie Reyna, the Lois and Melvin Tukman Professor of Human Development and director of the Cornell University Magnetic Resonance Imaging Facility. “And we have found, through our fMRI capabilities, that there is a correlate in the brain that corresponds to it.”In the study, published recently in the Journal of Experimental Psychology, Reyna and her team took a new approach. They applied fuzzy-trace theory, originally developed by Reyna to help explain memory and reasoning, to examine neural substrates of risk preferences and criminality. They extended ideas about gist (simple meaning) and verbatim (precise risk-reward tradeoffs), both core aspects of the theory, to uncover neural correlates of risk-taking in adults.
Participants who anonymously self-reported criminal or noncriminal tendencies were offered two choices: $20 guaranteed, or to gamble on a coin flip for double or nothing. Prior research shows that the vast majority of people would chose the $20 – the sure thing. This study found that individuals who are higher in criminal tendencies choose the gamble. Even though they know there is a risk of getting nothing, they delve into verbatim-based decision-making and the details around how $40 is more than $20.
The same thing happens with losses, but in reverse.
Given the option to lose $20 or flip a coin and either lose $40 or lose nothing, the majority of people this time would actually choose the gamble because losing nothing is better than losing something. This is the “gist” that determines most people’s preferences.
Those who have self-reported criminal tendencies do the opposite through a calculating verbatim mindset, taking a sure loss over the gamble.
“This is different because it is cognitive,” Reyna said. “It tells us that the way people think is different, and that is a very new and kind of revolutionary approach – helping to add to other factors that help explain the criminal brain.
As these tasks were being completed, the researchers looked at brain activation through fMRI to see any correlations. They found that criminal behavior was associated with greater activation in temporal and parietal cortices, their junction and insula – brain areas involved in cognitive analysis and reasoning.
“When participants made reverse-framing choices, which is the opposite of what you and I would do, their brain activation correlated or covaried with the score on the self-reported criminal activity,” said Reyna. “The higher the self-reported criminal behavior, the more activation we saw in the reasoning areas of the brain when they were making these decisions.”
Noncriminal risk-taking was different: Ordinary risk-taking that did not break the law was associated with emotional reactivity (amygdala) and reward motivation (striatal) areas, she said.
Not all criminals are psychopaths, but psychopaths show differences as well.
A study of 80 prisoners used functional MRI technology to determine their responses to a series of scenarios depicting intentional harm or faces expressing pain. It found that psychopaths showed no activity in areas of the brain linked to empathic concern. The participants in the high psychopathy group exhibited significantly less activation in the ventromedial prefrontal cortex, lateral orbitofrontal cortex, amygdala and periaqueductal gray parts of the brain, but more activity in the striatum and the insula when compared to control participants, the study found.The high response in the insula in psychopaths was an unexpected finding, as this region is critically involved in emotion and somatic resonance. Conversely, the diminished response in the ventromedial prefrontal cortex and amygdala is consistent with the affective neuroscience literature on psychopathy. (This latter region is important for monitoring ongoing behavior, estimating consequences and incorporating emotional learning into moral decision-making, and plays a fundamental role in empathic concern and valuing the well-being of others.)
- Damaging the insula can cure addiction:
The recent news about smoking was sensational: some people with damage to a prune-size slab of brain tissue called the insula were able to give up cigarettes instantly.
- The insula is responsible for the feeling of disgust:
Insula activation was only significantly correlated with ratings of disgust, pointing to a specific role of this brain structure in the processing of disgust. This ties in somehow to what I cited before on political leanings. In one study, people of differing political persuasions were shown disgusting images in a brain scanner. In conservatives, the basal ganglia and amygdala and several other regions showed increased activity, while in liberals other regions of the brain increased in activity. Both groups reported similar conscious reactions to the images. The difference in activity patterns was large: the reaction to a single image could predict a person’s political leanings with 95% accuracy (this may be hard to believe, but it is according to Neuroscientist Read Montague, who works at Virginia Tech in Roanoke. It is reported in newscientist.com which in turn cites his research article).
I’ve listed all these items, many very interesting, but at the end of the day, what is going on?
Structural and Functional Cerebral Correlates of Hypnotic Suggestibility – Alexa Huber, Fausta Lui, Davide Duzzi, Giuseppe Pagnoni, Carlo Adolfo Porro