Exploring the Impact of Ketamine on the Experience of Illusory Body Ownership

Abstract

BackgroundOur sense of body ownership is profound and familiar, yet it may be misleading. In the rubber-hand illusion, synchronous tactile and visual stimulation lead to the experience that a rubber hand is actually one's own. This illusion is stronger in schizophrenia. Given the evidence that ketamine, a noncompetitive N-methyl-D-aspartate antagonist reproduces symptoms of schizophrenia, we sought to determine whether the rubber-hand illusion is augmented by ketamine.MethodsWe studied 15 healthy volunteers in a within-subjects placebo-controlled study. All volunteers carried out two versions of the rubber-hand task, each under both placebo and ketamine infusions. In one task, they saw a rubber hand being stroked in synchrony with tactile stimulation of their real, hidden hand. In the other, stroking of the real and rubber hands was asynchronous. We recorded subjective changes in sense of ownership, as well as participants' ability to localize their hidden hand.ResultsKetamine was associated with significant increases in subjective measures of the illusion and in hand mislocalization. Although asynchronous visuotactile stimulation attenuates the strength of the illusion during both placebo and ketamine, there remained a significant illusory effect during asynchronous visuotactile stimulation under ketamine compared with placebo. The strength of the illusion during asynchronous visuotactile stimulation correlated with other subjective effects of the drug.ConclusionsKetamine mimics the perturbed sense of body ownership seen in schizophrenia, suggesting that it produces a comparable alteration in integration of information across sensory domains and in the subjective and behavioral consequences of such integration.

Predisposition to out-of-body experience (OBE) is associated with aberrations in multisensory integration: Psychophysiological support from a “rubber hand illusion” study.

“…These findings share some similarity to those of the present study in that either an administered drug (Morgan et al, 2011) or already present biases in multisensory integration (predisposition to OBEs) can lead to an increased tendency to accept ownership of an illusory limb. This occurs even when there is contradiction between sensory information (the asynchronous condition).…”

“…For example, Morgan et al, (2011) showed that the strength of the RHI is augmented by ketamine, a substance known to replicate the symptoms of psychosis and produce an altered sense of self.…”

Explaining Delusions: Reducing Uncertainty Through Basic and Computational Neuroscience

“…112 Furthermore, Ketamine augments experience of the rubber hand illusion, the spurious sense of ownership of a prop-hand if the hand is stroked at the same time as one's own hand. 113 People on ketamine get the illusion more strongly and they experience it even in a control condition when the real and rubber hands are stroked asynchronously. 113 Patients with schizophrenia 114 and chronic ketamine abusers show the same excessive experience of the illusion in the synchronous and asynchronous conditions.…”

Dexamphetamine effects on separate constructs in the rubber hand illusion test

“…Another useful approach for dissociating constructs of corporeal awareness is to administer a drug with well-defined actions on the central nervous system (e.g., Morgan et al 2010). Dexamphetamine is a relatively safe and effective drug that selectively releases dopamine, noradrenaline and, to a lesser extent, serotonin (Philips et al 1982;Hegadoren et al 1994).…”