Dunno. Its east to underestimate the difficulties. The brain is the most complex thing on the planet/ known universe. To be frank in relative terms of comparison present technology is not far from the level of a child's Meccano construction kit.
The above idea of graphene implants as super- miniaturised electrodes is interesting in terms of interface, and of course something which would be basic to allowing any serious cross-connectivity at all, but working with such a miniaturised and diaphanous material in actual biological living and growing tissue is I reckon problematic and fraught with difficulty in terms of stability.
Thanks for the book tip btw: I'll give it a go. I go through a couple of hundred novels a year (- a better waste of time than having a telly).