Monkeys recognize a wide variety of faces thanks to a brain area that specializes in face perception, according to a new study.
A team led by Doris Y. Tsao of Harvard Medical School in Boston used functional magnetic resonance imaging (fMRI) to identify three particularly face-responsive patches of brain tissue in each of two macaque monkeys. The researchers then implanted electrodes in each monkey's most-active brain area to record responses from a total of 310 neurons.
All but eight of these cells, or 97 percent, responded far more strongly to the sight of faces than to images of patterned grids, fruits, gadgets, or people's or monkeys' bodies and hands, Tsao and her colleagues report in the Feb. 3 Science. All sorts of faces elicited notable neural reactions, including human and macaque faces, familiar and unfamiliar faces, and cartoon faces.
The only other images that sparked activity, though weak, in these cells were clock faces and round fruits, whi