The Neuroscience of Consciousness: Global Workspace Theory, IIT, and Neural Correlates of Consciousness
Consciousness research was largely taboo in 20th-century neuroscience (considered too subjective and philosophical). In the 1990s, Francis Crick (Nobel laureate, DNA co-discoverer) and Christof Koch brought consciousness back into scientific view, proposing the research program of finding **Neural Correlates of Consciousness (NCC)** — the minimal neural activity set reliably correlating with specific conscious experiences.
## Global Workspace Theory: The Broadcasting Mechanism of Consciousness
**Global Workspace Theory (GWT)** by Bernard Baars (1988), with Stanislas Dehaene’s neuroscience version (Global Neuronal Workspace Theory, GNWT), is currently the best-supported neural consciousness theory. Core metaphor: the brain has many specialized local processors (visual, auditory, motor control) running in parallel in the “dark”; consciousness occurs when certain information is “broadcast” to the global workspace (mainly prefrontal-parietal networks) — like a theater spotlight making the entire audience see the stage. Neuroimaging shows conscious perception (vs. unconscious subliminal stimuli) accompanies delayed prefrontal-parietal activation (~300ms later) and long-range gamma-wave synchrony.
## Integrated Information Theory: Mathematical Measurement of Consciousness
**Integrated Information Theory (IIT)** by Giulio Tononi assigns consciousness a mathematical measure **Φ (phi)** — the degree of information integration exceeding the sum of system parts. Higher Φ = higher consciousness level. IIT’s striking implication: current deep learning systems may have near-zero Φ (relatively independent components); certain biological neural networks may have higher Φ than humans (panpsychist implications).
Medical application: [Owen et al. (2006)](https://www.science.org/doi/10.1126/science.1130197) in *Science* showed that patients diagnosed as vegetative state could follow fMRI instructions (imagining tennis or navigating a familiar house), revealing preserved consciousness without behavioral expression (locked-in syndrome) in some patients.
