Real faces that were presented to a monkey, together with reconstructions made by analyzing electrical activity from 205 neurons recorded while the monkey was viewing the faces. DORIS TSAOScientists have hypothesized that individual neurons are responsible for distinguishing individual faces. But now, researchers at Caltech have shown that the brains of macaque monkeys instead use a combinatorial approach to facial identity, in which each face-recognizing neuron responds to a particular aspect of faces.
By defining this combinatorial code, the scientists could reconstruct faces simply by observing neural activity. The study was published today (June 1) in Cell.
“People previously had this notion that neurons are coding specific identities,” says coauthor Doris Tsao of Caltech, but “the neurons are doing something more abstract than that. Each neuron is projecting a different axis. It’s simple and extremely mathematically elegant.”
Tsao and postdoc Steven Le Chang used an online face database to create a “face space” with 50 dimensions, half of which corresponded to facial appearance characteristics, such as skin texture, and half to face shape traits, such as eye height and face width. They used the face space to draw 2,000 random faces.
We “generated space where you could describe ...
