'Lizard brain' shapes social abilities in humans

Picture yourself at a social event. As the gathering comes to a close, and you step out, a barrage of thoughts flood your mind. Did you talk excessively? Did you unintentionally offend someone with a misplaced comment? Were your companions entertained or burdened by your presence?

This anxiety-inducing pattern of thought might seem frustrating, but it’s part of what makes us human – our brain’s advanced social cognitive abilities.

In a scientific study led by Northwestern Medicine, researchers have investigated the intricate evolutionary aspects of this phenomenon.

The study suggests that the human brain’s evolutionary advances in social cognition could be harnessed for future psychiatric therapies, potentially aiding those who suffer from anxiety or depression.

Lizard brain and social cognitive abilities

We often find ourselves caught up in thoughts, attempting to decipher the emotions and intentions of those around us.

“What is that person feeling, thinking? Did I say something to upset them?” noted senior author Rodrigo Braga.

This cognitive ability, however, is a recent addition to our evolutionary timeline. It involves placing oneself in another’s shoes and making educated guesses about their thought process, despite not having any concrete evidence.

The study aimed to decipher the link between the relatively new social cognitive network and the ancient part of the brain called the amygdala, also known as the “lizard brain.” The amygdala typically processes fear and detects threats.

Yet, it also governs social behaviors like parenting, mating, aggression, and social dominance hierarchies.

Ancient and advanced brain functions

The researchers found that the communication between the amygdala and the social cognitive network is ongoing.

In particular, the medial nucleus, a specific part of the amygdala that governs social behaviors, has a connection with the newly evolved social cognitive network areas that are linked to perceiving the emotions and intentions of others.

This link helps shape the social cognitive network’s function by granting access to the amygdala’s role in processing emotionally significant content.

To uncover these connections, the researchers turned to a noninvasive brain-imaging technique, known as functional magnetic resonance imaging (fMRI), which is used to measure brain activity by detecting variations in blood oxygen levels.

These high-resolution scans came courtesy of Kendrick Kay, a collaborator at the University of Minnesota.

The scans enabled the researchers to observe details of the social cognitive network that are not seen in lower-resolution brain scans.

Social cognition of the brain

Understanding the interplay between the amygdala and the social cognitive network offers significant insights into the evolutionary trajectory of the human brain.

This unique relationship represents a sophisticated adaptation that allows for higher-order social processing, an attribute crucial for the complex social structures that define human societies.

By aligning instinctual responses with advanced cognitive capabilities, this system equips humans with the ability to navigate intricate social landscapes, promoting cooperation, empathy, and theoretical thinking.

Such advancements have likely been pivotal in humanity’s survival and success as a species, reflecting an evolutionary advantage to processing social information.

Implications for anxiety and depression

Both anxiety and depression involve amygdala hyperactivity, which can lead to excessive emotional responses and impaired emotional regulation. Current treatments, like deep brain stimulation, are invasive because of the amygdala’s deep-seated location in the brain.

With the insights this study provides, transcranial magnetic stimulation (TMS), a less intrusive procedure, might be used to target the amygdala indirectly by focusing on the interconnected regions. This could offer a new, more comfortable treatment route for those dealing with these disorders.

Does this mean we are a step closer to alleviating the emotional load carried by millions around us? Only time will tell. But it is studies like these that keep inching us forward in our quest to better understand ourselves, our brains, and our shared humanity.

So next time you leave a social gathering and get swamped by intrusive thoughts about the way others see you, remember that it’s just your evolved human brain at work. And who knows, this advanced cognitive trait might offer a lifeline to many who grapple with their emotional well-being.

The study titled “The human social cognitive network contains multiple regions within the amygdala”  is published in the journal Science Advances.

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