All of us have been there. After leaving a gathering, you suddenly find your mind filled with thoughts of what other people were thinking. Scientists at Northwestern Medicine conducted a study to understand the evolution of humans’ ability to think about other people’s thoughts. These findings may have implications in the future for treating mental conditions like 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.”
According to the study, the ancient amygdala is in constant contact with the newly evolved parts of the brain which support social interaction. This part of the brain has been called the “social cognitive network”. The amygdala, also known as the “lizard brain,” is often associated with processing and detecting fear. The amygdala is best demonstrated by someone’s physical and emotional reaction to seeing a serpent: startled, heart racing, sweaty hands. Braga explained that the amygdala is also responsible for other functions. Braga is an assistant professor at Northwestern University Feinberg Medical School. “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.”
This study appeared in Science Advances on November 22.The study relied on high-resolution scans of the brain
and the findings were published in the journal Science Advances. The study is the first one to demonstrate that the medial nucleus of the amygdala connects to regions in the newly developed social cognitive networks, those involved with thinking about others. The amygdala is linked to this social cognitive network, which can access the role of the amygdala in the processing of emotionally significant content. Functional magnetic resonance imaging, a brain-imaging method that uses changes in blood oxygen to measure brain activity (fMRI), was the only way this could be done. Kendrick KAY, a collaborator and coauthor of the study at the University of Minnesota, gave Braga, Donnisa EDMONDS, and the Natural Scenes Dataset’s (NSD) cocorresponding author fMRI results from the brains of six participants. The high-resolution scans allowed the scientists to detect details in the social cognition network, which were not visible on the lower resolution brain scans. They were also able to reproduce the results up to twice in every individual. Edmonds is a Ph.D. student in Braga’s Northwestern lab. “That’s something that had been underappreciated before our study, and we were able to get at that because we had such high-resolution data.”
Treatment for anxiety or depression.
According to Edmonds, both anxiety and depression are associated with amygdala overactivity. This can lead to emotional outbursts and poor emotional regulation. Deep brain stimulation is currently available to treat either anxiety or depression. However, since the amygdala lies deep in the brain directly behind the eye, this would require an invasive surgical procedure. The authors say that with the findings of this study, it is possible to better treat patients using a less-invasive technique, called transcranial magnet stimulation (TMS).
“Through this knowledge that the amygdala is connected to other brain regions — potentially some that are closer to the skull, which is an easier region to target — that means people who do TMS could target the amygdala instead by targeting these other regions,” Edmonds said.
This study has the title, “The human social cognitive network contains multiple regions within the amygdala.” Christina Zelano and Joseph J. Salvo, Nathan Anderson and Qiaohan Yao.
