alt Hacker Newssee the open worm project to get an idea of what artificial neuronal architecture requires to express anything meaningful. (and an interesting ethical perspective on digital consciousness.) my point being that the number of neurons is fairly meaningless. you could take neuron models and link them circuit-style to play doom at the 10^2 scale if you wanted. from a cellular neurophysiological perspective, there's nothing particularly special here (as opposed to sentience/intelligence that's a paradigm shift beyond our understanding). and, in my opinion, absolutely nothing to be even the slightest bit worried about ethically.
I support further research along the lines of what is being done with neurons here, however, I don't think we quite know enough about consciousness or general self awareness (and how it comes about) yet to make sweeping generalizations saying there's _nothing_ to worry about. Proceeding with caution is always warranted when the stakes involve living organisms in my book.