Its not a petri dish he is referring to. He is talking about a brain implemented in silicon or graphene, i.e, a brain simulated on electronic hardware.
It doesn't matter what the brain is made of. Or would you say that if there are alien lifeforms, with their brains certainly made out of another matter than our brains, have no conscience?
I didn't mean that brain made up of silicon cannot be conscious. We are trying to simulate whatever we have learned about the brain. And that understanding is not complete. So implementing that in silicon (circuit) will not be conscious until we figure how to implement it.
Lots of what we know about the brain is implementation detail. For example brain architecture. Which part processes what. It's insignificant because when brain is young enough you can cut out whole hemisphere and end up with completely functioning individual.
When babys brain grows up it reassimilates most of the neurons that it grew. Architecture of the brain is shaped by funcion during development. The brain begins as generic structure that undegoes optimisations for the sole purpose of probably energy efficiency.
