Whether simple organisms like nematodes might possess minimal phenomenal consciousness is explored by reviewing current theories of consciousness in light of evidence from Caenorhabditis elegans, a worm with a nervous system of 302 neurons. The authors critically assess models such as global workspace theory, integrated information theory, and unlimited associative learning, and propose empirical approaches using C. elegans to test predictions about consciousness. The review does not reach a definitive conclusion but suggests that C. elegans may be a useful model for investigating the physical mechanisms of phenomenal consciousness.
During sleep, brain dynamics shift from wakefulness through NREM stages N1, N2, and N3, driven partly by decreases in the neuromodulators acetylcholine (ACh) and noradrenaline (NA). Analyzing fMRI data from healthy individuals and using a whole-brain model, the study shows that functional connectivity (FC) changes distinctly: locus coeruleus connectivity with the cortex decreases during N2 and N3, while basal forebrain connectivity with the cortex decreases during N3. Compared to wakefulness, the brain becomes more integrated in N1 and more segregated in N3. Region-specific neurotransmitter effects are key to explaining these FC changes, advancing understanding of how neurochemistry modulates sleep stages and consciousness transitions.