Consciousness Unbound: Ketamine and the Limits of the Global Neuronal Workspace Theory

This thesis critically evaluates the Global Workspace Theory (GWT) and its neuroscientific extension, the Global Neuronal Workspace Theory (GNWT), by examining how each attempts to explain the mechanisms underlying consciousness. GWT frames consciousness as a functional system that globally broadcasts information across distributed cognitive processes, while GNWT grounds this model with key neural signatures such as long-range frontoparietal connectivity, ignition, and P3 wave formation. Both theories primarily define consciousness in terms of access—the availability of information for verbal report, memory, and voluntary action—while sidestepping the subjective, phenomenal counterpart emphasized in philosophical accounts, particularly those by Ned Block. Building on the distinction between access and phenomenal consciousness and the challenge posed by Chalmers’ “hard problem,” I argue that treating access as equivalent to consciousness leaves these models empirically vulnerable. By looking at recent studies involving general anesthetic agents—particularly propofol and ketamine—I demonstrate that while both propofol-induced unconsciousness and unresponsiveness align with what GNWT predicts, sub-anesthetic doses of ketamine have led subjects to report vivid, dream-like experiences despite an absence of behavioral responsiveness. These findings potentially suggest that phenomenal consciousness persists without access consciousness, revealing a central limitation under GNWT’s framework. I argue that this dissociation under ketamine poses a challenge to how theories such as GNWT define and measure consciousness. Ultimately, this thesis aims to bridge philosophy and neuroscience, calling for a more nuanced understanding of conscious experience beyond access-based models, and proposes a “dual-state” brain hypothesis to account for preserved phenomenal content.