We know that the quality of the astrocytes matters a lot. It's not just about the quality of the neurons or their number or the way they are connected.

I'm afraid we don't know much more than that yet.

We have created frankenrodents with human astrocytes and they are a lot smarter than their unfranked counterparts. I bet we could learn a lot if we repeated the experiment with astrocytes from humans with different, known IQs.