The Social Brain
Social constructs are incredibly important to human beings but where does this sit in the brain?
The term the social brain was given to us in the 1990s. Researchers have attempted to find the social brain over decades and have found many structures and chemicals that can be related to aspects of sociality. And what we can see is that the social brain is way more complex than we could imagine and is a super network rather than a few isolated regions.
Just about everything human beings do is concerned with a social function of some sort. I am writing this with you the reader in mind. You are reading this because it interests you firstly, but because this will probably enable you to do some more stuff in life with other people or in social settings. This may be in business, in your career, in academia, with your family, etc. I have a family and many of my daily behaviours, and certainly daily routine revolves around this, even though my children are now older. I do business with people, for people, and to enable them to deal with people better. Our entertainment is about people, of people doing things we like such as playing music or doing art, but normally with other people. People, people, people. We are indeed, as Aristotle said, a social animal.
This is often forgotten because of the many features in our life that are social to some degree – hermits are rare, extreme introverts similarly. Human society is, well, a society, a huge collection of people doing things together or against each other.
The term social brain is generally ascribed to Robin Dunbar, a well-known anthropologist and evolutionary psychologist now head of the Social and Neuroscience Research Group at the University of Oxford. He noted that brain size of primates was larger, the larger the social group they lived in. This suggest that sociality is the single biggest driver of brain growth and complexity. Managing social relationships is a complex process and requires immense brain power. And who has the largest social groups of them all? Human beings, of course.
Robin Dunbar came up with what has now become known as the Dunbar number the "cognitive limit to the number of individuals with whom any one person can maintain stable relationships". This number is around 150 and a lot of research suggests this is pretty close to what we can observe in all settings including true friends on social media.
But back to the brain: do we have a social part of the brain or a social centre? If there is anything that is associated with social constructs, it is the neuromodulator oxytocin. But in this article let’s review areas of the brain.
At first glance it may seem like a toddle: put people in brain scanners and see what lights up when they look at people. Or maybe at people they like. But then again what about those extremely social individuals amongst us what makes their brains different? Or what about parenting? Those kind loving parents. Do they have different brains to harsher parents? So, as we ask these questions, we start to see that this is much more complex than we may assume. Colloquially we may speak of social people but there are many aspects and facets of this. Here are some things we may consider, and have been researched in the neurosciences:
Facial recognition
Nurturing
Pair bonding
Knowledge of the mind of others
Cooperation
Communication
Justice and equity
And then this is where it gets confusing because the following areas of the brain have been strongly associated with social thinking and interactions:
The medial prefrontal cortex
Temporal parietal junction
Precuneus
Pole of the temporal lobe
Fusiform gyrus
This is indeed a lot of regions and areas of the brain. Some of these are related to generalised emotions which are strongly activated by social situations. These include the nucleus accumbens network to rewarding and positive emotions and the amygdala network which is associated with fear and particularly threat. In reality the amygdala network can be considered a network of significance with threat taking a high priority for obvious reasons of survival. Other areas such as the Fusiform Face Area in the visual cortex has been shown to be specialised in facial recognition. So, let’s categorise some of this to try to create some clarity.
A better way to think of it is in groups of functions and many researchers group these broadly into the following areas:
Social cognition
Cognitive control
Affective (emotional) areas
Social cognition includes the big concept of theory of mind (TOM). Theory of mind is the ability to think about other people thinking, or make inferences from another’s perspective. This is something that develops in children starting around 4-5 but continues developing into adolescence. Indeed, this TOM or the ability to take perspective from another person, often called mentalizing, is what differentiates human beings from all other creatures. And this ability guides many of our thoughts and cognitive processes: judging what other people are thinking, making predictions of how they will respond, using this to our advantage in marketing and sales, and also in social manipulation and coercion.
From the above list we can see regions across the brain that are involved in this mentalizing network. These are regions that can combine multiple inputs and process - this to make inferences and predictions.
Cognitive control is also an important aspect of the social brain because this enables us to exert the control to function in socially acceptable ways, to respect hierarchies and not blurt out insults at the wrong time, for example. I reviewed the ACC previously and showed how it contributed to internal perceptions and conflict monitoring
The affective regions activate to gives us the emotional feedback from social scenarios. These can be threatening situations, to the pain of social rejection, to the joy of bonding with a loved one. These all trigger powerful emotional responses. Though I am focusing on the regions and networks here it is clear that these social inputs have massive emotional pull on our brains and bodies stimulating some of the strongest emotional responses that we have, and this is in combination with bunches of positive and negative chemicals and hormonal release and triggers.
An area that is consistently associated with the social brain is the medial prefrontal cortex. This is the part of the prefrontal cortex that sits on the inside of the hemisphere split and this region is involved in much of social processing with some research showing different aspects of this are processed in different areas.
Other areas are a little more exotic to the average person such as the temporal parietal junction which sits at and over the split between brain cortices, and the posterior superior temporal sulcus – sulcus being one of the “hills” of the brain.
Networks
What become clear very quickly is that these are operating in networks, and this is therefore what seems to be more important. Social skills are complex skills involving multiple areas so we may best look to broad networks rather than individual areas. The oxytocin network also influences this – oxytocin is a neuromodulator rather than a transmitter (see this article for review). The difference is important, it influences signalling over longer periods of time rather than being directly responsible for signalling between neurons. One paper calls the social brain a complex super network.
What also becomes noticeable is that many of these regions are either more recent evolutionary developments or sit between the cortices. This is interesting because when we look to the development of the brain and its expansion in human beings, we can see three noticeable differences.
Firstly, the prefrontal cortex has expanded dramatically. Human beings have a massive prefrontal cortex compared to primates.
Secondly, the regions between the cortices, so for example between the parietal and temporal regions, have expanded most with the brain, as our brains have developed. And it is precisely these regions that we see are involved in higher cognition and in this case particularly, social cognition.
Thirdly, as outlined previously the cerebellum has also grown disproportionality larger in human beings, suggesting an important role in all forms of cognition as I outlined in my review of this fascinating region.
Indeed, in recent research published in March 2021 the Max Planck Institute, one of the leading neuroscience research organisations, positions an area called the inferior parietal lobe as an area with which we interpret the world. Simply this area seems to serve as a coordinating and integrating region of complex mechanisms including language and communication.
A further fascinating study recently also showed the distribution of the social network as a separate but distributed system. In this case individuals were asked to solve problems individually and then with groups of people. What they saw is that the problem-solving network activated and when with groups of people additional resources were activated. This lay on top of the problem-solving network, or in parallel. This suggested two separate, distributed, and independent networks one for the problem solving and two for the social aspects of this.
Another clue to the social brain can be gleaned from research into antisocial people or psychopaths.
Differences in antisocial people
Research into psychopaths has shown differences in networks related to the emotional system. This gives us clues as to their lack of empathy or emotionally with others. They can conceptually understand suffering but are missing the empathy or emotional connections to this. Another recent piece of research hot off the press also gives us some clues to the anti-social brain: in this piece of research the researchers looked at the brain of agreeable and disagreeable people. Generally agreeable people are warm and empathic, and disagreeable people are cold, indifferent, and less caring or empathic. The fascinating result of this brain scanning study was the regions in the medial prefrontal cortex that social information was processed in. The participants did various tasks and exercises with objects and with people. And these are processed in different regions in the medial prefrontal cortex.
What was the difference?
The difference was that disagreeable people processed social information similarly to the way they processed objects whereas agreeable people processed social situations in different regions. This enabled the researchers to predict agreeable and disagreeable people from their brain activation patterns.
Babies
Research into babies gives us clues as to what is hard-wired and what is learnt (as I outlined in the article earlier on in-and out-groups). Cleary we are born with a brain that is primed for social interactions. Babies are naturally drawn to faces, to their mothers, and their suckling and grasping of the mother triggers oxytocin release.
Infants can identify positive and negative social interactions from as young as three-months old and appear to have a rudimentary moral understanding from this age. Evidence from research into rats also shows the devastating impacts of maternal separation with rat babies that have been separated from their mothers showing disrupted neuronal growth and destruction of grey matter and elevated cortisol throughout life. If we do not get the social connections we need, this simply has devastating impacts on our brain. This all points to the importance of social contact but also of how our whole brain body system is wired and primed for this social interaction.
So once again what is the social brain?
Ok, so where does this leave us? Well, the social brain is a key feature of the human brain. It is not so much that we have a social region in our brain but that our brain is designed to operate in social scenarios and is therefore distributed across the whole brain. A complex super network. But various aspects are critical: self-reflection and ability to transfer feelings from oneself to others is critical in social cognition and emotional connections and enables us to feel for others. This is driven by parts of the brain that have grown most in our recent evolution specifically prefrontal regions, the medial prefrontal cortex, and those regions between cortices such as the temporal parietal junction. This is also stimulated by oxytocin and the receptors we do, or do not have, which we review in the next article.
Disruptions in these systems can cause natural variation with some of us being more social, or less, or colder, less empathic. But also understand that just about everything we do has some relation to a social situation be that in family, bonding, sex, friendship, business, success, and the list could be endless.
So, Aristotle was right, we are a social animal - and our brains rather than having a social centre have a complex super network that has developed to be uniquely social.
References
Social brain
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Problem solving
Shpurov, I. Y., Vlasova, R. M., Rumshiskaya, A. D., Rozovskaya, R. I., Mershina, E. A., Sinitsyn, V. E., et al. (2020). Neural Correlates of Group Versus Individual Problem Solving Revealed by fMRI. Front. Hum. Neurosci. 14. doi:10.3389/fnhum.2020.00290.
Disagreeable people
Arbula, S., Pisanu, E., and Rumiati, R. I. (2021). Representation of social content in dorsomedial prefrontal cortex underlies individual differences in agreeableness trait. Neuroimage 235. doi:10.1016/j.neuroimage.2021.118049.
Adolescence
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Blakemore, S.-J. (2010). The developing social brain: implications for education. Neuron 65, 744–747.
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