Not sure if anyone here is familiar with the works of Joseph Chilton Pearce so I'd throw this out there to see if it strikes a chord with anyone. His work, IMO, is covering the mechanics of what McKenna alluded to with his diatribes against culture.. it talks about how we are neurally embedded in culture itself, how culture shapes us from birth and then how we in turn give rise to culture that ultimately blocks/retards the natural growth of the human being. It talks about the three fold brain and how essentially the highest most evolved part (neo-cortex/pre-frontal lobes) is serving the lowest oldest part (reptillian).. the opposite of what should be happening, and also about the brain in the heart. The last one is mentioned in New Age writing alot, but there is a scientific basis for this actually! Anyway, if you're interested there are 3 1hr dialogues with Joseph on "Living Dialogues" podcast.. highly recommended, and there's also a few clips on YouTube.
The Biology of Transcendence: http://www.youtube.com/watch?v=XFLshEzaMTc
The Biology of Transcendence: http://www.youtube.com/watch?v=XFLshEzaMTc