Three pioneers in face-perception research have won the 2024 Kavli Prize in Neuroscience.
Nancy Kanwisher, professor of cognitive neuroscience at the Massachusetts Institute of Technology; Winrich Freiwald, professor of neurosciences and behavior at Rockefeller University; and Doris Tsao, professor of neurobiology at the University of California, Berkeley, will share the $1 million Kavli Prize for their discoveries of the regions—in both the human and monkey brains—responsible for identifying and recognizing faces.
“This is work that’s very classic and very elegant, not only in face-processing and face-recognition work, but the impact it’s had on how we think about brain organization in general is huge,” says Alexander Cohen, assistant professor of neurology at Harvard Medical School, who studies face recognition in autistic people.
The Norwegian Academy of Science and Letters awards the prize every two years.
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anwisher says she long suspected that something special happens in the brain when we look at faces, because people with prosopagnosia—the inability to recognize faces—maintain the ability to recognize nearly all other objects. What’s more, it is harder to recognize an upside-down face than most other inverted objects, studies have shown.To get to the root of face processing, Kanwisher spent hours as a young researcher lying still in an MRI machine as images of faces and objects flashed before her. A spot in the bottom right of the cerebral cortex lit up when she and others looked at faces, according to functional MRI (fMRI) scans, she and her colleagues reported in a seminal 1997 paper. They called the region the fusiform face area.
This discovery offered some of the first concrete evidence that the brain specializes in sections, rather than working as a giant, adaptable generalist, Kanwisher says. “This shows that for some mental functions, there’s a very particular part of the brain that does just that and only that thing.”
The discovery “revolutionized how we thought about specialization of the brain,” Cohen says.
Two other face-sensitive regions—the occipital and superior temporal sulcus face areas—process parts of the face, such as the eyes, nose and mouth, and changeable aspects, such as gaze direction, subsequent work showed.
But knowing that regions of the human brain selectively respond to a face cannot tell a researcher much about how or why this happens, Kanwisher says. Tsao and Freiwald built on Kanwisher’s findings by carrying out studies in macaque monkeys to answer questions that studies in people could not. They used fMRI to scan 10 of the animals while showing them pictures of human faces, macaque faces, hands, gadgets, fruits and vegetables, headless bodies and scrambled patterns.
The monkeys’ brains have six distinct face patches, thought to be analogous to the areas seen in people, Tsao and Freiwald reported in a 2008 study.
Individual cells in these face patch regions specialize in recognizing faces seen from different angles—looking up, down, tilted to the side, and in profile, for instance—according to electrophysiological recordings, suggesting these specialized modules work together across regions, the team discovered.
Specific neurons can even recognize the different components that go into forming a face—from hair to pupils, Tsao and Freiwald found in additional work involving electrode recordings.
“That’s when we got this picture that the face patches are really like this assembly line that are building this invariant representation of facial identity,” Tsao says.
Two additional brain areas in macaques’ temporal lobe specifically respond to familiar faces and not unfamiliar ones, Freiwald and his colleagues later identified using fMRI.
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ombining these findings from humans and animals helps build a fuller understanding of the mind’s architecture, Kanwisher says. She has focused further lab work on identifying other specialized regions to construct such a picture: “The face system is just one little, teeny part of the brain and one little, teeny part of the mind. And I would like a broader picture of the organization of the whole mind,” she says.Tsao echoes her enthusiasm for the launchpad these findings have offered for future brain mapping. “When we first started working on the face-patch system, people said it’s a total unicorn,” Tsao says. “That turned out to be completely wrong. It turns out that the face-patch system basically is a Rosetta Stone for all of the IT [inferior temporal] cortex. All of the IT cortex is organized in exactly the same way.”
Understanding how we see faces can also be a tool for understanding more complex mental processes, such as memory and emotions, that are linked with social interactions, Freiwald says. “Faces are the social stimulus for visual and social animals like us.”
