Ketamine-Induced Hallucinations.

Abstract

BACKGROUND:

Ketamine, the NMDA glutamate receptor antagonist drug, is increasingly employed as an experimental model of psychosis in healthy volunteers. At subanesthetic doses, it safely and reversibly causes delusion-like ideas, amotivation and perceptual disruptions reminiscent of the aberrant salience experiences that characterize first-episode psychosis. However, auditory verbal hallucinations, a hallmark symptom of schizophrenia, have not been reported consistently in healthy volunteers even at high doses of ketamine.

SAMPLING AND METHODS:

Here we present data from a set of healthy participants who received moderately dosed, placebo-controlled ketamine infusions in the reduced stimulation environment of the magnetic resonance imaging (MRI) scanner. We highlight the phenomenological experiences of 3 participants who experienced particularly vivid hallucinations.

RESULTS:

Participants in this series reported auditory verbal and musical hallucinations at a ketamine dose that does not induce auditory hallucination outside of the scanner.

CONCLUSIONS:

We interpret the observation of ketamine-induced auditory verbal hallucinations in the context of the reduced perceptual environment of the MRI scanner and offer an explanation grounded in predictive coding models of perception and psychosis - the brain fills in expected perceptual inputs, and it does so more in situations of altered perceptual input. The altered perceptual input of the MRI scanner creates a mismatch between top-down perceptual expectations and the heightened bottom-up signals induced by ketamine. Such circumstances induce aberrant percepts, including musical and auditory verbal hallucinations. We suggest that these circumstances might represent a useful experimental model of auditory verbal hallucinations and highlight the impact of ambient sensory stimuli on psychopathology.

• Authors: Albert R Powers 3rd, Mark G Gancsos, Emily S Finn, Peter T Morgan, Philip R Corlett
• Journal: Psychopathology (Psychopathology) Vol. 48 Issue 6 Pg. 376-85 ( 2015) ISSN: 1423-033X [Electronic] Switzerland
• PMID: 26361209 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2015 S. Karger AG, Basel.

Chemical References

• Ketamine

Topics

• Adult
• Delusions (chemically induced)
• Dose-Response Relationship, Drug
• Female
• Frontal Lobe (drug effects, physiopathology)
• Hallucinations (chemically induced, diagnosis)
• Humans
• Ketamine (administration & dosage, adverse effects)
• Magnetic Resonance Imaging
• Male
• Perception
• Psychotic Disorders (drug therapy, pathology)
• Young Adult