One, not two, neural correlates of consciousness.
Trends in Cognitive Sciences June 1, 2005 B. Baars, Steven Laureys
The authors critique Ned Block's distinction between phenomenological consciousness (what we experience) and access consciousness (information accessible via conscious experiences). They argue that evidence from cognitive neuroscience does not support this division. For instance, visual cortex activity is necessary but not sufficient for conscious visual qualities; without parietal and prefrontal activation, no correlation with consciousness is found. Similarly, when frontoparietal regions are impaired, sensory consciousness is absent despite sensory cortex activation. The authors contend that unconscious brain mechanisms interact with visual cortex to enable visual qualities, and that positing a separate 'access consciousness' is unnecessary. They suggest that what is needed is simply consciously-mediated access to brain capacities, most of which are unconscious.