A new MRI study has located the cingulate cortex as the brain region responsible for forming positive or negative associations with people's faces. The researchers also experimented with manipulating the emotional responses of their subjects, ie. inducing them to feel a certain way about certain faces.
"Face recognition is a very important social function for people," said Takeo Watanabe, co-author of the new study from Brown University. "Facial recognition is associated with people's emotions."
The study, published in PLOS Biology, could lead to advancements in treating mood and anxiety disorders, say the researchers, but the findings could also be harmful and used in brainwashing. The technique is called DECNEF, which stands for decoded neurofeedback. Using DECNEF on MR images of the cingulate cortex, the researchers looked at study participants' reactions to pictures of various faces. They recorded their emotional responses to the faces, then showed the face pictures again briefly before asking the participants to perform a task for a reward. Unbeknownst to the participants, they were rewarded only when their emotional response matched the brain activity the researchers were trying to produce. When they were shown the face pictures again at a later time, their feelings had shifted from their initial responses to the responses the researchers had induced.
These tests took place over a period of several days; the researchers estimate that stronger responses could be induced after a longer period.