This paper has found that you need 1000 artificial neurons to simulate a real one. This doesn't say much about the actual complexity of a neuron though, e.g. I'

This paper has found that you need 1000 artificial neurons to simulate a real one. This doesn't say much about the actual complexity of a neuron though, e.g. I'm sure you need many neurons to simulate a Fourier transform, even though the Fourier transform only has a few mathematical terms (in other words, the true complexity of a FT is much lower). What would tell us about its actual complexity though is if we knew how many "variables" the formula describing a single neuron has, which should be approximated by how many degrees of freedom in nature does its genetic description have.