Toward an Explanation of the Genesis of Ketamine-Induced Perceptual Distortions
Ketamine is an anaesthetic drug for human and veterinary use. However, it is also a drug that is used recreationally due to its ability to induce lighter and more short-lived hallucinations than LSD. It also produces perceptual distortions. In a paper in Brain and Mind, Pereira and Johnson present a thorough investigation of how ketamine […]
Ketamine is an anaesthetic drug for human and veterinary use. However, it is also a drug that is used recreationally due to its ability to induce lighter and more short-lived hallucinations than LSD. It also produces perceptual distortions.
In a paper in Brain and Mind, Pereira and Johnson present a thorough investigation of how ketamine actually induce these states. This study, it is claimed, also sheds light on normal states of consciousness.
Toward an Explanation of the Genesis of Ketamine-Induced Perceptual Distortions and Hallucinatory States
Alfredo Pereira Jr. and Gene Johnson in Brain and Mind Volume 4, Number 3
Abstract The NMDA receptor (NMDAR) channel has been proposed to function as a coincidence-detection mechanism for afferent and reentrant signals, supporting conscious perception, learning, and memory formation. In this paper we discuss the genesis of distorted perceptual states induced by subanesthetic doses of ketamine, a well-known NMDA antagonist. NMDAR blockage has been suggested to perturb perceptual processing in sensory cortex, and also to decrease GABAergic inhibition in limbic areas (leading to an increase in dopamine excitability). We propose that perceptual distortions and hallucinations induced by ketamine blocking of NMDARs are generated by alternative signaling pathways, which include increase of excitability in frontal areas, and glutamate binding to AMPA in sensory cortex prompting Ca2+ entry through voltage-dependent calcium channels (VDCCs). This mechanism supports the thesis that glutamate binding to AMPA and NMDARs at sensory cortex mediates most normal perception, while binding to AMPA and activating VDCCs mediates some types of altered perceptual states. We suggest that Ca2+ metabolic activity in neurons at associative and sensory cortices is an important factor in the generation of both kinds of perceptual consciousness.
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