Interest in ketamine as a treatment for substance use disorders has grown because it blocks NMDA glutamate receptors and because glutamate signaling is linked to depression and addiction. This narrative review covers clinical evidence from the 1970s to 2025, focusing on randomized blinded controlled trials. Nine such trials have tested ketamine for cocaine (three studies), alcohol (three studies), opioid use disorder (two studies), and nicotine (one study). The evidence suggests ketamine is effective for addiction when combined with psychotherapies, especially at doses that produce mystical or psychedelic experiences. The review calls for more rigorous studies to determine which addictions ketamine may treat, optimal dosing, the role of concurrent psychotherapies, safety monitoring, and contraindications.
Perceptual multistability, where a single sensory input gives rise to alternating perceptions, offers clues about the relationship between perceptual awareness and consciousness. The work argues that studying these phenomena can reveal how the brain constructs conscious experience from ambiguous information. It suggests that perceptual awareness is not a single state but a dynamic process involving competition between neural representations. The text discusses how multistable perception can help disentangle the neural correlates of consciousness from those of perceptual content, providing a framework for understanding conscious awareness.