title: Dissociative part-dependent resting-state activity in dissociative identity disorder: a controlled FMRI perfusion study.
abstract: BACKGROUND
  In accordance with the Theory of Structural Dissociation of the Personality (TSDP), studies of dissociative identity disorder (DID) have documented that two prototypical dissociative subsystems of the personality, the "Emotional Part" (EP) and the "Apparently Normal Part" (ANP), have different biopsychosocial reactions to supraliminal and subliminal trauma-related cues and that these reactions cannot be mimicked by fantasy prone healthy controls nor by actors.
  
  
  METHODS
  Arterial spin labeling perfusion MRI was used to test the hypotheses that ANP and EP in DID have different perfusion patterns in response to rest instructions, and that perfusion is different in actors who were instructed to simulate ANP and EP. In a follow-up study, regional cerebral blood flow of DID patients was compared with the activation pattern of healthy non-simulating controls.
  
  
  RESULTS
  Compared to EP, ANP showed elevated perfusion in bilateral thalamus. Compared to ANP, EP had increased perfusion in the dorsomedial prefrontal cortex, primary somatosensory cortex, and motor-related areas. Perfusion patterns for simulated ANP and EP were different. Fitting their reported role-play strategies, the actors activated brain structures involved in visual mental imagery and empathizing feelings. The follow-up study demonstrated elevated perfusion in the left temporal lobe in DID patients, whereas non-simulating healthy controls had increased activity in areas which mediate the mental construction of past and future episodic events.
  
  
  CONCLUSIONS
  DID involves dissociative part-dependent resting-state differences. Compared to ANP, EP activated brain structures involved in self-referencing and sensorimotor actions more. Actors had different perfusion patterns compared to genuine ANP and EP. Comparisons of neural activity for individuals with DID and non-DID simulating controls suggest that the resting-state features of ANP and EP in DID are not due to imagination. The findings are consistent with TSDP and inconsistent with the idea that DID is caused by suggestion, fantasy proneness, and role-playing.
authors.affiliation: Division of Neuropsychology, Institute of Psychology, University of Zurich, Zurich, Switzerland.
authors.forename: Yolanda R
authors.initials: YR
authors.lastname: Schlumpf
authors.affiliation: Department of Neuroscience, University Medical Center Groningen, and BCN Neuroimaging Center, University of Groningen, Groningen, The Netherlands; Department of Psychosis Studies, Institute of Psychiatry, King's College London, London, United Kingdom.
authors.forename: Antje A T S
authors.initials: AA
authors.lastname: Reinders
authors.affiliation: Top Referent Trauma Center Mental Health Care Drenthe, Assen, The Netherlands.
authors.forename: Ellert R S
authors.initials: ER
authors.lastname: Nijenhuis
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland.
authors.forename: Roger
authors.initials: R
authors.lastname: Luechinger
authors.affiliation: Department of Radiology, C. J. Gorter Center for High-Field MRI, Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Matthias J P
authors.initials: MJ
authors.lastname: van Osch
authors.affiliation: Division of Neuropsychology, Institute of Psychology, University of Zurich, Zurich, Switzerland; International Normal Aging and Plasticity Imaging Center, University of Zurich, Zurich, Switzerland.
authors.forename: Lutz
authors.initials: L
authors.lastname: Jäncke
mesh_terms: D000328:Adult; D001931:Brain Mapping; D016022:Case-Control Studies; D009105:Dissociative Identity Disorder / Q000503:physiopathology*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography; D008875:Middle Aged