Let's define the terms. What does it mean "with similar capacity"? As far as I understand xvilka was taking about the number of artificial neurons required to model a biological neuron times the number of biological neurons in the human brain. It is modelling its physical structure (on a neuronal level).
That is we have unknowns that might increase or decrease estimates of computational demands of a functionally equivalent ANN. Not everything that happens in the brain contributes to information processing.
