[vinceguidry]

But if the substrate had artificial neurons, that could do everything normal neurons could, then it's plausible that consciousness could copy everything over. At that point, the only thing binding consciousness is the 'idea' that it belongs to the cells.

If you separated them before the host dies, then you'd have copied the consciousness into the substrate, and they would exist separately until you reattached it.

Wait until the host dies, then the consciousness would experience that death yet still persist. It would carry on experiencing through whatever senses the substrate offers.

Notice that it's not just a signal being transferred, it's the actual mechanics of consciousness, neurons firing and communicating. When the substrate, connected to the brain, communicates, it's just as if you added brain cells. So it's not just a signal, it's actual thought.