AT: "it is the collective activity of such cells when they are organized into the right kind of brain mechanism (e.g., the retinoid mechanism) that realizes the property of consciousness"

'Realizes'?  What does that mean?    (Ditto for "You are simply ignoring an overwhelming body of evidence supporting the idea that consciousness is realized by some particular kind of brain activity.) 

 AT: "I've argued that consciousness is a transparent representation of the world from a privileged egocentric perspective. I'd be interested in your principled argument against this definition of consciousness."

I have so many questions about what you mean by it, I couldn't possibly argue against it.

AT: "I disagree. If we want a better understanding of consciousness we must refer to specific instances of its content and relate these to the human condition. An analysis of the creative "vision" of the artist can illuminate the role that consciousness must play in a peculiarly human activity. We can then address the question  of how such a vision might be generated."

Again too many words to sort out (eg ' specific instances of its content' ,'human condition', 'vision'...)

DA