July 16, 2021 – This flash of familiarity we feel when we see someone we know has long fascinated and baffled scientists, who have been unable to determine what is going on in the brain. But for the first time, researchers are now reporting a new class of cells they say is responsible.
The discovery goes against the prevalent idea in neuroscience that various areas of the brain must communicate with each other to process information. Instead, this study shows that a region of the brain appears to function for the sole purpose of identifying people we know.
It was believed that a single brain cell – called a grandmother’s neuron, due to its ability to identify familiar faces, like that of a person’s grandmother – would be discovered, but this has yet to be discovered. been done.
The problem is so ingrained in neuroscience that senior author Winrich Freiwald, PhD, professor of neuroscience and behavior at Rockefeller University in New York, says that when one scientist wants to ridicule another’s argument, he dismiss it as “just another grandma’s neuron,” or some unproven theory.
Now, in an obscure and little-studied area of the brain, Freiwald says they’ve found the closest thing to a grandmother’s neuron in cells that can link facial perception to memory.
The cell grandmother
For their study, Freiwald and his colleagues recorded electrical signals from neurons in the brains of two rhesus monkeys as they were shown pictures of faces; some of the people they knew and some they didn’t know.
The team showed that neurons in the lower frontal part of the brain, the temporal pole, play a role in identifying familiar faces and the ability to tell the difference between familiar faces and new ones.
In fact, neural responses were three times stronger for the faces of people the monkeys knew personally than for the faces of people they didn’t know, even though they had seen those faces on screens multiple times.
This could underscore the importance of knowing someone in person, the researchers say. Given the current trend to interact virtually, we need to be aware that the faces we have seen on a screen may not evoke the same neural activity as the faces we meet in person.
With this information, scientists can begin to study how these brain cells encode familiar faces. The researchers say they can now wonder how this region is connected to other parts of the brain and what happens when a new face appears.
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