Memory functions in the brain work according to a principle that neuroscientists call «sparse coding», i.e. a comparatively small
number of neurons encode complex information — possibly to make overlap between different memories more unlikely.
The central insight
of the new work is that even though there exist an infinite
number of different possible faces, our brain needs only about 200
neurons to uniquely
encode any face, with each
neuron encoding a specific dimension, or axis,
of facial variability.