My biggest accomplishments in Minecraft so far have been building my dream home (complete with fireplace, library, greenhouse, and swimming pool) and a five-way track switcher that I definitely did not copy off a Youtube video. Redditor AllUpInHyuh, on the other hand, created what he or she is calling "a working neuron".
An Imgur gallery is accompanied by snippets of text like the following:
The box on the left represents the extracellular concentration of sodium (initially high). Stacks will be drawn out and "diffuse" into the intracellular chest.
Gold pressure plate can be thought of as a binding site for neurotransmitters. As the number of sprites released from dropper grows, the signal from plate increases. The quantity of items in chest determines the threshold for stimulation.
I have no idea what any of that means, but given that the discussion in the comments turned almost immediately to this project's hypothetical applications toward creating artificial intelligence, I think we can conclude that it's pretty serious. After all, according to this sciencey-looking page, a human brain contains roughly 100 billion neurons. That seems doable, right?