In the 1960s, neuroscientists found out that a certain brain cell lights up when at the sight of the person's grandmother's face. Due to that, scientists call this cell the "grandmother neuron". However, some scientists immediately dismissed this idea because they believe no single neuron corresponds to one idea or person only.
After 50 years, new research on monkeys shows that the grandmother neuron must truly exist after finding a small area of the monkey's brain that responds to familiar faces. They noted that there is three times the number of brain cells in this area that respond to a familiar face than to an unfamiliar one.
Winrich Freiwald, a professor of neuroscience and behavior at The Rockefeller University in New York City, said that these cells are in some way could be the grandmother neuron, having the unique combination of vision and memory.
Researchers published their study, titled "A fast link between face perception and memory in the temporal pole," in the journal Science.
Grandmother Neuron Explained
According to the Encyclopedia of Neuroscience, a grandmother neuron is a neuron that codes for very specific information, which is the grandmother only. Evidence suggests that specific coding comes from the sensory neurons and is stored in memory.
The team examined the temporal pole, which was a poorly understood area located near the bottom of the brain ad one of the two areas that might be responsible for facial recognition.
They used fMRI to scan the brains of two rhesus monkeys while they looked at images of other monkeys, human faces, and random images, according to Live Science. The electrodes they placed in the temporal pole and one area that responds to faces enabled them to monitor the activity of individual brain cells of these areas.
They found that both areas lit up when monkeys saw photos of their family and friends, in which the temporal pole cells lit up three times more compared to when unfamiliar faces appeared.
This study proves that there is a specific area in the brain with a single purpose and that is to recognize familiar faces, debunking previous wisdom in neuroscience.
Furthermore, the team obscured some of the images to see how the brain responses would differ. They found that the response from temporal pole cells was different. It responded very little when highly blurred images were shown but not on images of familiar faces. The team believes this effect is the "a-ha!" moment when recognizing a familiar face.
Not the Grandmother Neuron
The cells in the temporal pole region act like sensory cells but also like memory cells. However, the team clarifies that these cells are not grandmother neurons. Instead, cells in this region work in concert.
Freiwald noted that this region is more of a "grandmother face area" of the brain. Its discovery at the heart of facial recognition means that scientists will soon start how cells in that region encode familiar faces.
"We can now ask how this region is connected to the other parts of the brain and what happens when a new face appears," Freiwald asks, according to Science Daily. "And of course, we can begin exploring how it works in the human brain."
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Read also: Neuroscience
