The Tatiana and krista experiment is quite interesting but stretches the concept of communication to it's limits. I am inclined to say that having a shared part of your conciousness is not communication in the same way that sharing a house is not traffic. It does strike me that communication involves directed construction of thoughts and it's easy to imagine that the scope of what this construction is capable would be vastly smaller than what goes on in the brain in other processes. Extending the construction to new types of thoughts might be a soft border rather than a hard one. With enough verbal sentences it should be in principle to be able to reconstruct an actual graphical image, but even with overtly descriptive prose this level is not really reached (I presume) but remains within the realm of sentence-like data structures.

In the example Tatiana directs the visual cortex and Krista can just recall the representation later. But in a single conciouness brain nothing can be made "ready" but it must be assembled by the brain itself from sensory inputs. That is cognitive space probably has small funnels and for signficant objects they can't travel them as themselfs but must be chopped off into pieces and reassembled after passing the tube.