Frontiers in Human Neuroscience
January 1, 2014
Robin Carhart‐Harris, Robert Leech, Peter J. Hellyer et al.
1,289 citations
Entropy, a measure of uncertainty or disorder, is applied to brain function and consciousness, focusing on the psychedelic state induced by psilocybin. The psychedelic state is considered a primary or primitive state of consciousness, characterized by elevated entropy in brain function, including a greater repertoire of functional connectivity motifs that form and fragment over time. This suggests primary states may exhibit criticality, a transition zone between order and disorder. Normal waking consciousness suppresses entropy, operating just below criticality, which constrains cognition and enables metacognitive functions like reality-testing and self-awareness. Entry into primary states involves collapse of default-mode network activity and decoupling from medial temporal lobes. These hypotheses can be tested by comparing brain activity in REM sleep, early psychosis, normal waking consciousness, and anesthesia.
Journal of Neuroscience
January 8, 2014
Peter J. Hellyer, Murray Shanahan, Gregory Scott et al.
225 citations
During an attentionally demanding task, brain activity becomes more synchronized and less variable over time compared to rest. This shift is linked to increased activity in the frontoparietal control/dorsal attention network and decreased activity in the default mode network. A computational model confirmed that activating the frontoparietal network increases synchrony and reduces variability, while activating the default mode network does the opposite. The balance between these networks may control how the brain shifts between an unfocused, exploratory state with high variability and a focused, constrained state with low variability.
arXiv Preprint Archive
March 20, 2025
Murray Shanahan
The article explores whether consciousness can be defined in a way that fits modern, disembodied AI systems while withstanding philosophical critique. It examines how subjective time and selfhood might manifest in such an entity, finding that the attempt pushes the language of consciousness to its limits. The inquiry ultimately points toward a concept akin to Buddhist emptiness, challenging dualistic views of subjectivity and selfhood. The argument suggests that our usual frameworks for understanding consciousness may be inadequate for AI, leading to a rethinking of fundamental assumptions.