Spoiling the party: Long-term ketamine use has long-term effects on bodily experience
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1
ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Department of Cognitive Science, Australia
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2
Department of Psychiatry, University of Cambridge, United Kingdom
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3
Institute of Mental Health, the Second Xiangya Hospital, Central South University, China
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4
Department of Psychiatry, Ribicoff Research Facility, Yale University, United States
The popular party drug, ketamine, causes schizophrenia-like symptoms when administered acutely, in a clinical setting, and when used recreationally. To investigate the dissociative changes in bodily experience associated with ketamine, which also characterise schizophrenia, we used a popular paradigm for investigating ‘sense of ownership’ (SoO): the Rubber Hand Illusion (RHI). Here, healthy participants come to feel that a rubber hand is their hand, when their own hand is hidden from view. This illusion is more readily experienced in schizophrenia and by healthy participants after an acute infusion of ketamine. Although significant efforts have been made to identify neural markers of the RHI and of a prediction error signal linking psychosis and ketamine, it is unclear if repeated ketamine use has long-lasting effects on SoO.
We induced the RHI using visuotactile stimulation to the index finger of the rubber hand and the participant’s own hand, either synchronously or asynchronously in time (assuming asynchrony attenuates the illusion). We measured the strength of the illusion using the change in perceived hand location (proprioceptive drift) and a subjective self-report questionnaire. We compared two groups: 26 chronic ketamine users and 20 healthy controls. All participants completed questionnaires to assess schizotypy and the presence of schizophrenia-like symptoms.
As expected, chronic ketamine users experienced the illusion more strongly according to both measures, however there were some differences in the impact of synchrony of visuotactile stimulation between groups. Measures of depersonalisation, bodily experience and dissociative experience were positively correlated with subjective experience and proprioceptive drift but these were modulated by the type of visuotactile stimulation.
Frequent ketamine use therefore induces persistent alterations in bodily experience, irrespective of synchronicity of multisensory inputs. I discuss these findings in the context of how multisensory processing and the RHI is represented in the brain. I consider the implication that chronic ketamine effects are distinct from acute effects or infrequent use, and the suggestion that acute ketamine disrupts inferential processing whereas chronic use results in aberrant learning and updating of priors. Thus, I also discuss how we should interpret this behavioural approach and its relevance to a prediction-error model of psychosis.
Keywords:
body ownership,
rubber hand illusion,
Ketamine,
psychosis,
Sensory Processing*
Conference:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference, Clayton, Melbourne, Australia, 28 Nov - 1 Dec, 2013.
Presentation Type:
Poster
Topic:
Sensation and Perception
Citation:
Morgan
HL,
Tang
J,
Fletcher
PC,
Corlett
PR and
Chen
X
(2013). Spoiling the party: Long-term ketamine use has long-term effects on bodily experience.
Conference Abstract:
ACNS-2013 Australasian Cognitive Neuroscience Society Conference.
doi: 10.3389/conf.fnhum.2013.212.00009
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Received:
15 Oct 2013;
Published Online:
25 Nov 2013.
*
Correspondence:
Dr. Hannah L Morgan, ARC Centre of Excellence in Cognition and its Disorders, Macquarie University, Department of Cognitive Science, Sydney, NSW, 2109, Australia, hannah.morgan@mq.edu.au