
'Overthinking what you said? It’s your "lizard brain" talking to newer, advanced parts of your brain'
The paper is open access.We’ve all been there. Moments after leaving a party, your brain is suddenly filled with intrusive thoughts about what others were thinking. “Did they think I talked too much?” “Did my joke offend them?” “Were they having a good time?”
In a new Northwestern Medicine study, scientists sought to better understand how humans evolved to become so skilled at thinking about what’s happening in other peoples’ minds. The findings could have implications for one day treating psychiatric conditions such as anxiety and depression.
“We spend a lot of time wondering, ‘What is that person feeling, thinking? Did I say something to upset them?’” said senior author Rodrigo Braga. “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, and that implies that it’s a recently developed process. 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.”
The study found the more recently evolved and advanced parts of the human brain that support social interactions — called the social cognitive network — are connected to and in constant communication with an ancient part of the brain called the amygdala.
Often referred to as our “lizard brain,” the amygdala typically is associated with detecting threats and processing fear. A classic example of the amygdala in action is someone’s physiological and emotional response to seeing a snake: startled body, racing heart, sweaty palms. But the amygdala also does other things, Braga said.
“For instance, the amygdala is responsible for social behaviors like parenting, mating, aggression and the navigation of social-dominance hierarchies,” said Braga, an assistant professor of neurology at Northwestern University Feinberg School of Medicine. “Previous studies have found co-activation of the amygdala and social cognitive network, but our study is novel because it shows the communication is always happening.”