1. To slightly change your question, with regard to the structure of microcircuitry in the brain, of which cytoarchitecture is a purely anatomical component, we

1. To slightly change your question, with regard to the structure of microcircuitry in the brain, of which cytoarchitecture is a purely anatomical component, we are just starting (as in about a decade or two in, but nothing systematic). Cajal and Brodmann did the pure cytoarchitectural studies over 100 years ago, and that is well understood. There are many ongoing projects to gather and characterize this across all human brain regions, most of the effort in the community centers around the BigBrain project, but not all of it is publicly available yet since many of the projects to make use of that data are just finishing their first 'grad student' cycle. On a more fundamental level we are just starting to do a systematic survey of the types of neurons in the brain (previous smaller studies have been done for decades, but have been very hard to compare [1]). We need to have that as a foundation to be able to meaningfully catalogue the circuits that are composed of them. In a bad analogy, we need to have names for the basic discrete circuit components in the brain (resistor, capacitor, transistor, etc.) before we can come up with something like a Horowitz and Hill for the neural circuits. 2. Yes, people are working on this, but whether the neurons that are created are actually like the ones in a living brain require much more research. The search term for this is 'neural conversion' and the key paper is [2]. 3. It is either much simpler, or much more complicated. Axons send projections along signalling gradients during development and have something akin to a lock and key system (made of cell surface proteins) that help them hit the correct targets. If you can make the signal and design the lock and key, in theory it would work. The issue of course is that we have zero idea what sticking a specific new connection in will do, though there is this paper which suggests that pure connectivity changes can have a gain of function [3]. The other area to look in for stuff related to this is axonal repair (spinal cord repair), and that is where all the theory seems to go out the window because there are so many signals that the neurons listen to. If you dig in there you will see that people have tried scaffolds, signals, stem cells, and all other manor of hocus pocus to get it to work because the search space they are in is terrifyingly huge. 0. https://en.wikipedia.org/wiki/BigBrain https://en.wikipedia.org/wiki/BigBrain 1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3619199/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3619199/ 2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756723/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756723/ 3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5774341/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5774341/