An individual neuron has no ethical concerns at all. A talking, thinking Futurama-style "head in a jar" would be obviously awful. The problem is that I have no

An individual neuron has no ethical concerns at all. A talking, thinking Futurama-style "head in a jar" would be obviously awful. The problem is that I have no clue where to draw the line between these two scenarios. How many neurons does it take for consciousness?