Consciousness requires both functional integration and differentiation in the brain, a property termed brain complexity. Transcranial Magnetic Stimulation combined with electroencephalography (TMS/EEG) can quantify this complexity. Studies consistently show that the complexity of the cortical response to TMS collapses during loss of consciousness in deep sleep, anesthesia, and vegetative state after severe brain injury. Complexity recovers when consciousness returns during wakefulness, dreaming, the minimally conscious state, or locked-in syndrome. This approach may help understand the pathophysiology of disorders of consciousness and requires careful methodological attention.
Disruptions in neural oscillations, particularly in the gamma and theta frequency ranges, are a key mechanism by which THC, the primary psychoactive component of cannabis, perturbs brain function. Clinical EEG studies show that both chronic and acute cannabinoid exposure disrupts these neural oscillations in humans. The authors propose a hypothetical framework where endocannabinoids modulate neural synchrony at the network level, altering the fine tuning of oscillations and the inhibitory/excitatory balance of neural circuits. These oscillatory disruptions may relate to cannabis-induced changes in sensation, perception, and cognition, with implications for disorders such as schizophrenia.