That is a good explanation. I'll point out for anyone that clicks through, that unlike what he says, depth in ANNs do serve a purpose: to make learning more tra

That is a good explanation. I'll point out for anyone that clicks through, that unlike what he says, depth in ANNs do serve a purpose: to make learning more tractable by building representational abstractions. There are feedback and recurrent connections in the brain but what (2) means to say that the specific mechanism is not biologically plausible. I know there are prominent Deep learning researchers who are trying to work around this but those explanations have never struck me as particularly parsimonious. It's better to start an explanation from experimental data on brains than from them most important aspect of neural nets.