It is really not that simple unfortunately, CMOS the only submicron technology that can be produced with sufficient repeatability and noone has come up with a p

It is really not that simple unfortunately, CMOS the only submicron technology that can be produced with sufficient repeatability and noone has come up with a proposal yet how to produce a CMOS chip with that integration density, what you have to realize is that each neuron has typically up to 1000 connections to other neurons so you need to fit in 75*1000 synapse circuits in your design as well. That is already 2 orders more transistors than any currently produced chip.