What does a newly discovered brain network in monkeys mean for us?

When we interact with other people we make guesses about how and what they are feeling or thinking and predict how they will react. But we do not know for sure as these processes take place in their mind.

The ability to attribute and recognize mental states like feelings, thoughts, desires and intentions – in oneself and in others and how these mental states might affect behaviour is known as the Theory of Mind. It is also an understanding that others’ feelings, emotions, thoughts, desires and intentions are completely different from our own.

But most interestingly, the scientists discovered that other areas of the brain far removed from the face and body selective areas, also perked up in response to social interaction stimuli.

These processes take place in the mind which is not observable and therefore we cannot know for sure what goes on in the mind of others but we can only intuit, guess or ascertain based on assumptions made from our own beliefs, emotions and perceptions – an essential human trait which is important for social interaction.

But what mechanism takes place in the human brain to support the theory of mind?

Scientists from Winrich Freiwald’s Laboratory of Neural Systems at The Rockefeller University have discovered some compelling clues about the origins of our ability to understand what other people are thinking or feeling.

As monkeys recognize social interactions and their meanings quickly and effortlessly, the scientists used magnetic resonance imaging (MRI) in macaque monkeys to scan their brains while they watched different kinds of videos.

Some of the videos showed inanimate objects like monkey toys colliding or interacting physically. Other videos had macaques interacting with the same objects like playing with them and more videos showed macaques interacting with each other like playing, grooming, fighting etc.

By analysing the MRI scans, scientists found areas on the monkeys’ brains which responded to physical interaction or to social interaction.

But the findings were surprising. Instead of seeing the expected areas of the brain containing specialised cells called mirror neurons fire up when the monkeys watched other monkeys playing with toys, the researchers noticed that the macaques’ mirror neuron regions became active even when they watch other monkeys interacting socially and also when they watched object collide with each other.

This suggests that the motor neuron system, which also exists in the human brain, could be more involved than previously thought in social and inanimate interaction.

When the monkeys watched videos featuring visual shapes such as faces, bodies or objects, those areas of the brain which respond to visual shapes also got activated.

However, the body-selective areas of the monkeys ‘brains got more activated when they watched videos of monkeys interacting with objects. The face-selective areas became more active in response to videos of monkey-on-monkey social interaction.

This led to the suggestion that the same parts of the brain responsible for visual shapes may be responsible for analysing physical and social interaction.

But most interestingly, the scientists discovered that other areas of the brain far removed from the face and body selective areas, also perked up in response to social interaction stimuli.

The researchers also found a portion of the network that responded entirely to social interaction which  otherwise remained silent in the absence of social interactions.

This socially sensitive network is located in the same areas of the brain associated with the theory of mind in humans. These areas only get activated when we reflect on the thoughts of others.

The study suggests that the extent and location of this system suggests that this network may be the evolutionary forerunner to the neural network in our brain which produces the theory of mind mechanism and human mind-reading capabilities.

And it perhaps suggests that we, humans, are not that different from primates as we would like to think.

Source: Science