ABSTRACT
The global workspace (GW) theory described in chapter 7 (this volume) has a natural neurophysiological interpretation. We can perform a neural contrastive analysis of conscious versus unconscious events to pinpoint brain structures and processes that are clearly related to consciousness as such. The most obvious examples are wellknown structures whose lesioning abolishes conscious wakefulness: the brainstem reticular formation, the reticular nucleus of the thalamus, and the nonspecific spray of neurons that emerges from the intralaminar nucleus of the thalamus to "activate" the cortex (creating the distinctive electrophysiological signature of waking consciousness). Further, studies of blindsight from damage to the primary visual projection area (VI) make a persuasive case that the contents of a conscious visual experience depend on an intact area VI. Similar results have been reported for the somatosensory primary projection area and the auditory primary projection area. This system of neural structures can indeed be interpreted as a high-level global workspace. In addition to the lesioning evidence, they appear to fit two general properties of global workspace systems, namely competition for input to the GW and widespread dissemination of its output (Baars, 1993; Newman & Baars, 1994). Recent PET scan studies of novel versus automatic perceptualmotor skills show very widespread high glucose utilization when the task is novel and therefore more conscious followed by a dramatic drop in metabolic activity as it becomes automatic, precisely as would be expected from GW theory.
