Led by physician-scientist Josef Parvizi, researchers from Stanford Medicine recently uncovered the shocking role of a tiny structure known as the anterior precuneus (aPCu)– which plays a key role in forming “I,” or our physical sense of self.
The structure is located right in between the two constantly collaborating hemispheres of the brain, and the team found that this epicenter is critical for merging information about motion, location, sensations, and muscle and joint positions to create a mental map of our sense of physical self.
To better explain the significance of aPCu, Parvizi relied on the notions of “I” and “me.”
“For every action we take, even during dreams, there’s always an agent behind it: We call that agent ‘I.’ ‘Me’ is everything we have stored in our memories about the ‘I,'” he said.
In the brain, different structures control two distinct systems that are always talking to each other.
One system deals with our physical sense of self—the “I”—which is like how we feel in our own bodies. The other is about our narrative self—the “me.” This part is about our memories, our habits, our personalities, how we feel about others, and what’s coming up next in life.
Our narrative self has a well-known home in the brain. It’s called the default mode network. Even though it might sound like three random words thrown together, this term actually tells us about a network in the brain that gets busy when we’re daydreaming or remembering things.
The bodily-self network doesn’t have a catchy name yet, but scientists know it’s there. Previous studies have pointed out bits and pieces of it, but now there’s more info about its main player, the aPCu.
To get more details about this network led by the aPCu, Parvizi’s team did some brain imaging. They looked at data from five patients and nearly a thousand participants in the Human Connectome Project, which has been working since 2010 to map how the brain’s connections work.