"Seen <particular face>" is a binary state, so one output neuron that fires on recognizing a particular face is actually quite reasonable.
Obviously, the inputs that contribute to that recognition must be more complicated.
EDIT: As dragonwriter says below, lower levels of neural networks are responsible for general facial recognition but that triggers more specific neurons once the recognition is done from generic face -> specific person. Even in artificial neural networks single bit is sufficient at the end of the classification.
A neuron is interconnected to many others, but this doesn't mean one neuron is many neurons, any more than one binary bit is 64 binary bits by virtue of its position in a binary word.
http://www.klab.caltech.edu/koch/
Sorry my post evoked such a harsh response from you.
This is nonsense, citation needed.
> For example, You have a one special neuron in your brain that fires when you see Bill Clinton's face.
This is New Age science, i.e. not science at all. It's a myth. One neuron is equivalent to one bit in a computer. One bit of information is insufficient to distinguish between faces.
> And that exact neuron fires no matter what picture of Bill Clinton you happened to see.
Maybe you could learn a tiny bit of neuroscience before spreading this kind of nonsense.