In:
Psychopathology, S. Karger AG, Vol. 48, No. 6 ( 2015), p. 376-385
Abstract:
〈 b 〉 〈 i 〉 Background: 〈 /i 〉 〈 /b 〉 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. 〈 b 〉 〈 i 〉 Sampling and Methods: 〈 /i 〉 〈 /b 〉 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. 〈 b 〉 〈 i 〉 Results: 〈 /i 〉 〈 /b 〉 Participants in this series reported auditory verbal and musical hallucinations at a ketamine dose that does not induce auditory hallucination outside of the scanner. 〈 b 〉 〈 i 〉 Conclusions: 〈 /i 〉 〈 /b 〉 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.
Type of Medium:
Online Resource
ISSN:
0254-4962
,
1423-033X
Language:
English
Publisher:
S. Karger AG
Publication Date:
2015
detail.hit.zdb_id:
1483565-4
detail.hit.zdb_id:
605604-0
