Overthinking what you said? It’s your ‘lizard brain’ talking to newer, advanced parts of your brain

New research reveals how our prehistoric brain regions collaborate with newer neural networks to fuel social anxiety and self-reflection

Published in Science Advances | Estimated reading time: 4 minutes

Ever caught yourself replaying a social interaction in your mind, wondering if you talked too much or if your joke fell flat? Northwestern Medicine researchers have discovered that this very modern form of social anxiety actually stems from an ancient partnership in our brains – one that connects our primitive “lizard brain” with newer, more sophisticated neural networks.

The study, led by Dr. Rodrigo Braga, offers unprecedented insights into how humans developed their remarkable capacity for social cognition. Using advanced brain imaging techniques, researchers have mapped previously unseen connections between the amygdala – our ancient emotional center – and recently evolved brain regions that specialize in social thinking.

“The parts of the brain that allow us to do this are in regions of the human brain that have expanded recently in our evolution,” explains Braga, an assistant professor of neurology at Northwestern University Feinberg School of Medicine. “In essence, you’re putting yourself in someone else’s mind and making inferences about what that person is thinking when you cannot really know.”

This discovery challenges our traditional understanding of the amygdala, often simplified as our “fear center.” While it does process threats – triggering that familiar racing heart when we spot a snake – it also plays sophisticated roles in parenting, mating, and navigating social hierarchies. The study reveals that a specific region called the medial nucleus serves as a crucial bridge between our primitive emotional responses and our modern social awareness.

The research team employed cutting-edge functional magnetic resonance imaging (fMRI) to capture these neural connections in unprecedented detail. “One of the most exciting things is we were able to identify network regions we weren’t able to see before,” notes Donnisa Edmonds, a neuroscience Ph.D. candidate involved in the study. This technical breakthrough allowed researchers to confirm their findings multiple times in each participant, lending robust support to their conclusions.

These insights could revolutionize treatment approaches for conditions like anxiety and depression, where the amygdala often shows hyperactivity. Rather than requiring invasive deep brain stimulation, future treatments might target connected regions closer to the skull using transcranial magnetic stimulation (TMS), offering a gentler alternative for patients struggling with social anxiety.

Key Terms Glossary

  • Amygdala: An ancient brain structure that processes emotions and social behaviors, nicknamed the “lizard brain”
  • Social Cognitive Network: Recently evolved brain regions that enable us to think about others’ thoughts and feelings
  • Medial Nucleus: A specific part of the amygdala that connects primitive emotional responses with advanced social thinking
  • Transcranial Magnetic Stimulation (TMS): A non-invasive treatment that uses magnetic fields to stimulate specific brain regions

Test Your Understanding

Why is the amygdala sometimes called the “lizard brain”?

It’s one of our most evolutionarily ancient brain structures, handling primitive functions like threat detection and basic social behaviors that even reptiles possess.

What surprising role does the amygdala play beyond processing fear?

The amygdala is involved in complex social behaviors including parenting, mating, and understanding social hierarchies.

How might this research improve treatment for anxiety?

By understanding the amygdala’s connections to other brain regions, doctors might be able to use non-invasive TMS treatment targeting accessible connected areas rather than the deep-seated amygdala itself.

What made this study’s findings possible?

High-resolution fMRI scans allowed researchers to see previously undetectable details of brain connections, particularly in the social cognitive network.


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