How Brain Recognizes Faces

Scientists at the California Institute of Technology have created perfect replicas of human faces that were shown to monkeys just from recording the animal’s brain signals. Doris Tsao, who’s the lead author of the study, says her work has solved one of the most intractable problems in neuroscience – “how the brain recognizes faces.” She also believes the demonstration will one day have practical applications in forensics where “one could reconstruct the face of a criminal by analysing a witness’s brain activity,” the Guardian reports.

In the study, two rhesus macaque monkeys were shown images of human faces. Using functional magnetic resonance imaging, researchers recorded the regions of the brains that lit up when the animals saw a face, and focused on those hotspots to see what the face cells were doing. The researchers again introduced a set of 2,000 human faces with varying characteristics, such as the distance between the eyes or the shape of the hairline, for the monkeys to see.

The researchers then implanted electrodes into the macaques’ brains to compare the responses of individual neurons to the facial differences. The team recorded a total of 205 neurons between the two monkeys, each responding to a specific combination of some of the facial parameters, according to Nature. The signals from just that small number of cells can encode enough information to be able to differentiate a new face the brain has encountered, researchers say. And, once the researchers knew what facial characteristic each cell was responding to, they were able to show the monkeys a new face, record the cellular activity and reconstruct the face with remarkable accuracy based on what neurons were doing, Engadget notes.

Reference: The Code for Facial Identity in the Primate Brain. Cell, 2017. DOI: 10.1016/j.cell.2017.05.011