The Face Code
How the brain identifies human faces has long remained a mystery. Researchers now know about brain cells that specialize in faces and whose reactions can be described mathematically. Visual perception in general could be based on the same basis.
As a student at the California Institute of Technology, I heard about the groundbreaking experiments of David Hubel and Torsten Wiesel. The two Nobel Prize-winning neurophysiologists had discovered how the brain's primary visual cortex extracts edges from images provided by the eyes.
Thus, neuroscience can be used to understand how neural activity generates conscious perception. I can hardly describe the excitement this realization gave me. I had found my lifelong dream: to study how visual perception works and how the brain uses electrical activity to encode perceived objects – not just simple lines, but also elusive objects like faces. So the question was: Which brain regions are involved and which patterns of neural impulses enable us to identify our fellow human beings?
My journey of discovery began as a graduate student at Harvard University, where I researched stereoscopic vision: the mechanism that creates the impression of spatial depth from the differences between the images of the two eyes. I came across a paper by neuroscientist Nancy Kanwisher, then at the Massachusetts Institute of Technology, and her colleagues on brain imaging of human subjects. With the help of functional magnetic resonance imaging (fMRI), the working group had identified a brain region that reacted much more strongly to images of faces than to representations of other objects. That sounded downright absurd to me…
