In my June brain column for Discover, I wrote about the bizarre idea that there are single neurons in your head that can respond to individual people. The so-called “grandmother cell” started out 40 years ago as a thought experiment riffing on Philip Roth’s novel Portnoy’s Complaint. By the 1970s, most neuroscientists considered it more of a joke than a valid concept, but in the years since it hasn’t quite gone away.
In my column, I described the work of the work of Rodrigo Quian Quiroga of the University of Leicester:
For the past eight years, he and his colleagues have been studying epilepsy patients who have had electrodes implanted in a region of their brains called the medial temporal lobe, as part of a study to identify the source of their seizures. Quian Quiroga showed the subjects 100 pictures. The pictures included photos and drawings of celebrities as well as landmarks and various familiar objects. The patients had to press one button if a picture was of a human face and another if it was not.
In their first such study, Quian Quiroga and his team were able to observe the individual activity of 993 neurons. They found that 132 of them responded to at least one picture. And of those responding neurons, 51 fired in response to only a single person or thing. One neuron responded only to Halle Berry, for example.
Amazingly, the “Halle Berry” neuron responded to any picture of her, including one in which she was dressed as the masked Catwoman. Even the name Halle Berry triggered that neuron, which was silent at the sight of other actresses or their names.
Quian Quiroga does not, however, believe these neurons are grandmother cells, at least as they were initially conceived. He suspect that a very sparse network of neurons–perhaps hundreds out of the billions in our heads–can develop this kind of response to an individual. Quian Quiroga just happen to stick his electrodes near single neurons that belonged to these networks.
Which brings us to Quian Quiroga’s latest paper, published in Current Biology. He analyzed the signals from 750 electrodes implanted in seven patients as they looked at pictures of some celebrities like Oprah Winfrey. Quian Quiroga found neurons that responded strongly to the sight of these individuals–and they also responded strongly to their written names and even the sounds of their names.
Quiroga and his colleagues also ran the same test using themselves rather than the celebrities to probe for neurons. They discovered neurons that responded strongly only to individual researchers, too–and once more, the same neurons responded to the sight and sound of their name. Bear in mind–the patients had only met the scientists a day or two earlier. So these neurons had developed their grandmother-ish response in a very short time.
These results offer some clues to how these sparse networks are arranged. Some of the neurons probably get signals from other regions of the brain that recognize faces. Others tap into auditory networks, and others language centers. Yet, remarkably, the information from these far-flung parts of the brain get funneled into tiny sets of neurons that can then encode concepts of people.
They may not be the Grandmother Cells of legend, but in their own way, they’re very cool.
Reference: Quian Quiroga et al., Explicit Encoding of Multimodal Percepts by Single Neurons in the Human
Brain, Current Biology (2009), doi:10.1016/j.cub.2009.06.060
Related Topics
Go Further
Animals
- Octopuses have a lot of secrets. Can you guess 8 of them?
- Animals
- Feature
Octopuses have a lot of secrets. Can you guess 8 of them? - This biologist and her rescue dog help protect bears in the AndesThis biologist and her rescue dog help protect bears in the Andes
- An octopus invited this writer into her tank—and her secret worldAn octopus invited this writer into her tank—and her secret world
- Peace-loving bonobos are more aggressive than we thoughtPeace-loving bonobos are more aggressive than we thought
Environment
- Listen to 30 years of climate change transformed into haunting musicListen to 30 years of climate change transformed into haunting music
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- U.S. plans to clean its drinking water. What does that mean?U.S. plans to clean its drinking water. What does that mean?
- Food systems: supporting the triangle of food security, Video Story
- Paid Content
Food systems: supporting the triangle of food security - Will we ever solve the mystery of the Mima mounds?Will we ever solve the mystery of the Mima mounds?
History & Culture
- Strange clues in a Maya temple reveal a fiery political dramaStrange clues in a Maya temple reveal a fiery political drama
- How technology is revealing secrets in these ancient scrollsHow technology is revealing secrets in these ancient scrolls
- Pilgrimages aren’t just spiritual anymore. They’re a workout.Pilgrimages aren’t just spiritual anymore. They’re a workout.
- This ancient society tried to stop El Niño—with child sacrificeThis ancient society tried to stop El Niño—with child sacrifice
- This ancient cure was just revived in a lab. Does it work?This ancient cure was just revived in a lab. Does it work?
Science
- The unexpected health benefits of Ozempic and MounjaroThe unexpected health benefits of Ozempic and Mounjaro
- Do you have an inner monologue? Here’s what it reveals about you.Do you have an inner monologue? Here’s what it reveals about you.
- Jupiter’s volcanic moon Io has been erupting for billions of yearsJupiter’s volcanic moon Io has been erupting for billions of years
- This 80-foot-long sea monster was the killer whale of its timeThis 80-foot-long sea monster was the killer whale of its time
Travel
- How nanobreweries are shaking up Portland's beer sceneHow nanobreweries are shaking up Portland's beer scene
- How to plan an epic summer trip to a national parkHow to plan an epic summer trip to a national park
- This town is the Alps' first European Capital of CultureThis town is the Alps' first European Capital of Culture
- This royal city lies in the shadow of Kuala LumpurThis royal city lies in the shadow of Kuala Lumpur