How Does the Brain Process Imitating Others?

The saying "monkey see, monkey do" goes back to the 18th century in Jamaica to describe imitation or mimicry. 300 years later, scientists have discovered two regions in the front of the brain associated with such behavior.

Japanese researchers from the Nationa Institutes of Natural Sciences recently published their study in the journal Nature Communications. The ventral premotor cortex (PMv) and medial prefrontal cortex (MPFC) regions were observed to play a major role in processing and responding to social cues.

The PMv and MPFC contain mirror neurons that signal self-actions, partner actions, or both actions. It is the same neurons believed to influence social qualities like empathy or sympathy.

Previous research has not found how these two brain regions work together and affect social behavior. The mirror neurons are also hypothesized to be deficient in people with autism who struggle with forming intimate relationships and social interactions. A connection between the two brain regions is what keeps us from making default, emotionless decisions.

Copy Cat Game

During the study, macaques were trained to play a game with a partner where they received rewards after pressing buttons. At times, the rules changed and the monkeys made mistakes. Other times, the mistakes were carelessly made.

Masaki Isoda said, "Monkeys continued using the same rule if they thought the other monkey's mistakes were accidental," However if the mistakes were associated with new rules of the game, they adjusted accordingly. The monkeys interacted with three partners - a real monkey, a recorded monkey, and inanimate objects.

More partner cells in the MPFC were discovered than in the PMv and were most active when the monkeys played with a real partner. Meanwhile, self-type neurons were more prevalent in the PMv.

Brain Neurons and Autism

When PMv neurons were temporarily silenced, the monkeys made more mistakes when mirroring the mistakes of their partner. Taihei Ninomiya said that it was as if an autistic monkey was playing the game. "As difficulty understanding social cues is a hallmark of autism, understanding the role of the PMv-mPFC pathway provides a good direction for future research into autism spectrum disorders," said Ninomiya.

Human neuroimaging has previously shown that the two areas are rarely independently active. This suggests that the PMv and MPFC have mutual or divergent roles in social cognition, wrote the authors.

They also applied the Granger causality analysis to understand how information flowed between two live partners in the game. They discovered that brain activity flowed from the PMv to the MPFC when the partners executed and observed actions.

Neuroimaging of the macaques revealed that MPFC is active during social observations, but became inactive during physical actions and interaction. "The present findings indicate that the ability of the MPFC to monitor the other's action depends on input from the PMv, supporting a coordinative relationship between the two areas." the authors concluded.

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