title: Can motor imagery and hypnotic susceptibility explain Conversion Disorder with motor symptoms?
abstract: Marked distortions in sense of agency can be induced by hypnosis in susceptible individuals, including alterations in subjective awareness of movement initiation and control. These distortions, with associated disability, are similar to those experienced with Conversion Disorder (CD), an observation that has led to the hypothesis that hypnosis and CD share causal mechanisms. The purpose of this review is to explore the relationships among motor imagery (MI), hypnotic susceptibility, and CD, then to propose how MI ability may contribute to hypnotic responding and CD. Studies employing subjective assessments of mental imagery have found little association between imagery abilities and hypnotic susceptibility. A positive association between imagery abilities and hypnotic susceptibility becomes apparent when objective measures of imagery ability are employed. A candidate mechanism to explain motor responses during hypnosis is kinaesthetic MI, which engages a strategy that involves proprioception or the "feel" of movement when no movement occurs. Motor suppression imagery (MSI), a strategy involving inhibition of movement, may provide an alternate objective measurable phenomenon that underlies both hypnotic susceptibility and CD. Evidence to date supports the idea that there may be a positive association between kinaesthetic MI ability and hypnotic susceptibility. Additional evidence supports a positive association between hypnotic susceptibility and CD. Disturbances in kinaesthetic MI performance in CD patients indicate that MI mechanisms may also underlie CD symptoms. Further investigation of the above relationships is warranted to explain these phenomena, and establish theoretical explanations underlying sense of agency.
authors.affiliation: Movement Neuroscience Laboratory, Department of Exercise Sciences, the University of Auckland, New Zealand; Centre for Brain Research, the University of Auckland, New Zealand.
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Srzich
authors.affiliation: Movement Neuroscience Laboratory, Department of Exercise Sciences, the University of Auckland, New Zealand; Centre for Brain Research, the University of Auckland, New Zealand.
authors.forename: Winston D
authors.initials: WD
authors.lastname: Byblow
authors.affiliation: Movement Neuroscience Laboratory, Department of Exercise Sciences, the University of Auckland, New Zealand; Centre for Brain Research, the University of Auckland, New Zealand.
authors.forename: James W
authors.initials: JW
authors.lastname: Stinear
authors.affiliation: Movement Neuroscience Laboratory, Department of Exercise Sciences, the University of Auckland, New Zealand; Centre for Brain Research, the University of Auckland, New Zealand.
authors.forename: John
authors.initials: J
authors.lastname: Cirillo
authors.affiliation: Movement Neuroscience Laboratory, Department of Exercise Sciences, the University of Auckland, New Zealand; Centre for Brain Research, the University of Auckland, New Zealand. Electronic address: g.anson@auckland.ac.nz.
authors.forename: J Greg
authors.initials: JG
authors.lastname: Anson
mesh_terms: D000818:Animals; D003291:Conversion Disorder / Q000150:complications*; D006990:Hypnosis; D007092:Imagination / Q000502:physiology*; D007699:Kinesthesis; D051379:Mice; D009069:Movement Disorders / Q000150:complications*
keywords: Conversion Disorder; Hypnosis; Hypnotic susceptibility; Kinaesthetic motor imagery; Motor imagery; Motor suppression imagery