A Tiny Part of an Already Small Brain Region Helps Us Decide How Generous or Selfish To Be
It's called the basolateral amygdala
Hiya!
If asked to name the defining features of humanity, I’d bet our generous nature, compassion, and empathy would be relatively high on your list. While not entirely unique to our species, we take particular pride in our altruistic tendencies to help others.
However, such benevolence is not distributed equally, in that we tend to help and feel most compassion for those with whom we have strong emotional ties than for strangers. It’s a simple Truth, yet how the brain navigates the decision of who and when to bestow our aid has been a mystery.
That’s changing now, thanks to a curious researcher who wondered how generosity changes depending on how much, or little, people care about each other emotionally. He and his international team of experts decided to find out and discovered a small brain structure that plays an active role in calibrating our generosity based on emotional closeness or distance.
Social Discounting
Before I tell you about the research, let’s discuss generosity for a moment.
It’d be nice if we provided equal generosity to anyone and everyone whenever we can. If we lived in a world in which we’re just as willing to spend a weekend helping our best friend move as we are to assist a stranger in the same task.
But that isn’t reality.
The Truth is, our generosity is a spectrum, and it declines as our emotional and social distance to the recipient of our help increases. Psychologists call this inclination of ours “social discounting.”
Going back to the moving example, generally speaking, while you may not be thrilled about giving up a weekend to help your friend, it probably feels less like a burden than doing it for a stranger or acquaintance.
You may feel like I’m pointing out the obvious, but such social calculations, and how our brain makes them, aren’t as evident.
Though we have a better idea now, thanks to new research by Tobias Kalenscher, a professor and head of the Comparative Psychology research team at Heinrich Heine University Düsseldorf (HHU), Germany.
Kalenscher, whose expertise lies at the intersection of psychology, neuroscience, and economics, grew curious about our social discounting tendencies. In an article he penned for Scientific American about research he led that I’ll tell you about soon, he wrote that he wondered:
[W]hat happens in the brain when we make these decisions? And why are some people more generous to socially distant individuals than others are?
He and his international team of researchers suspected that a small, often-overlooked brain region may be involved. So, they decided to find out. But before I tell you about the study, it’ll be helpful to know a bit about the brain region of interest — the basolateral amygdala.
The Basolateral Amygdala
You’ve probably heard of the amygdala and know it’s a small, almond-shaped brain region nestled deep in our temporal lobe, and that it’s heavily involved in emotional processing, especially fear.
You might even know that the amygdala is part of the limbic system, a network of interconnected brain structures that help regulate our emotional behaviors.
But you may not know that the amygdala is composed of 13 nuclei organized into five major groups — basolateral nuclei, cortical-like nuclei, central nuclei, other amygdaloid nuclei, and the extended amygdala — each of which plays a specific role in the amygdala’s function.
And, over the last few decades, research has shown that, beyond emotional behaviors, the amygdala, as a whole, is also essential for navigating our social relationships — but especially the basolateral amygdala (BLA), located beneath and to the side of the region, which is known to help regulate our behavioral and physiological responses to stress.
When a person with an intact basolateral amygdala decides whether to be generous or selfish, they’ll weigh the consequences or benefits of a range of social variables, including learned social norms, expectations, and instructions, as well as the social context of the situation.
In his article, Kalenscher mentioned mounting research showing that, across species, the basolateral amygdala is involved in empathic responses, the evaluation of social rewards, and decisions concerning others.
He points to studies involving rodents and monkeys, in which neurons in their basolateral amygdala encoded the values of rewards they received and the rewards others received. As for humans, he says,
“[T]he structure has been linked to traits such as trust, empathy, moral decision-making, and extraordinary altruism. Human amygdala volume also correlates with the size and complexity of a person’s social network.”
As is so often the case, we learn a lot about a system when it doesn’t function as it should. This makes researchers especially interested in the few people who have Urbach-Wiethe disease.
Among the symptoms of this rare genetic condition is that it’s known to cause targeted, bilateral damage to the basolateral amygdala while leaving the rest of the brain intact.
A news release by HHU about the research I’ll tell you about soon (I promise) explains,
The emotional life and social behaviour of Urbach-Wiethe subjects differ. Above all, they find it difficult to recognise the emotional meaning of facial expressions. There are less than 150 known cases worldwide, but a larger group of Urbach-Wiethe subjects lives in Namaqualand in northern South Africa.
While the emotional life and social behaviors of people with Urbach-Wiethe differ, previous research has found that this group can display what’s known as pathological altruism.
For instance, classic experiments in behavioral economics include the trust game, in which participants choose how much money to give another participant, the “trustee.” The amount shared is usually multiplied, and the trustee then decides how much to return. Researchers use the initial amount a participant sends as a measurement for the level of trust they have in the trustee.
And studies have found that people with damage to their basolateral amygdala tend to give far more to others during the trust game, even when the trustees don’t reciprocate or demonstrate that they’re untrustworthy.
Similarly, another study asked people with Urbach-Wiethe to respond to moral dilemmas involving made-up life-or-death scenarios about others. The researchers found that compared to people without Urbach-Wiethe, people with the condition consistently refused to harm one person to save many, suggesting a strong reluctance to be responsible for causing harm to another.
So, Kalenscher wondered,
“How, exactly, does the basolateral amygdala influence our decisions about whether to help others?”