Case 5 - The Woman who Left Her Body (OBEs) Flashcards
Out of Body Experience (OBE):
Definition: A sensation of consciousness detached from the body, where a person perceives themselves as awake, observing their body and the world from a location outside the physical body.
Abnormal Egocentric Visuospatial Perspective: The self seems to be located in a second body hovering above the physical body.
Autoscopic Phenomena (AP):
Types: Includes OBE (feeling of being outside one’s physical body) and Autoscopy (seeing one’s body in extrapersonal space from the habitual visuospatial perspective).
Prevalence of OBE/AS:
Occurrence: Associated with neurological diseases (epilepsy, migraine, neoplasia, infarction, infection) and psychiatric diseases (schizophrenia, depression, anxiety), but not restricted to these populations.
Healthy Population: OBE/AS occurs in the healthy population with a prevalence of approximately 10% at least once or twice in a lifetime, cross-culturally.
Blanke et al., 2004 Study:
Objective: To describe correlates of OBE/AS in six patients using various methods, including phenomenological interviews, repeated or long-term EEGs, neurological and neuropsychological tests, and structural MRI.
Subjective Results: Three experienced OBE, four experienced autoscopy, with some patients reporting both. Self-recognition was preserved even if the face was not visible.
Visual Phenomenology: Detailed descriptions of visuospatial perspectives during OBE and AS, including elevation, inversion, and vividness.
Non-Visual Phenomenology: Involvement of vestibular sensations, emotions (fear/elation/neutral), and illusory flexion or transformation of limbs.
Objective Results:
Findings: Four out of six patients had epileptic seizures, and partial consciousness was related to transitory ischemic attack/migraine in two cases. Lesion analysis showed overlaps centered on the Temporo-Parietal Junction (TPJ). Cortical stimulation experiments were conducted.
Electrical Stimulation of OBEs:
De Ridder et al., 2007 Study: Electrical stimulation of the right superior temporal gyrus in a tinnitus patient did not suppress tinnitus but reliably produced “OBEs” with disembodiment experiences.
Components of OBEs:
Proposed Components (Blanke et al., 2004):
- Multisensory Disintegration: Failure to integrate visual, tactile, and proprioceptive information about the body. Involvement of TPJ.
- Vestibular Dysfunction: Suggested as a second component, leading to experiences such as supernumerary phantom limbs.
TPJ (Temporo-Parietal Junction):
Role: Implicated in visuospatial perspective-taking. Active during ego-centric perspective changes. Role in hemispatial neglect.
Involvement: Identified in the integration of proprioceptive, visual, and tactile information about body position during OBEs.
Vestibular Dysfunction:
Speculation: Proposed as a component of OBEs, contributing to experiences like seeing one’s own body in a position that does not coincide with the felt position.
Supernumerary Phantom Limbs (SPL): Mentioned as a related phenomenon, suggesting a potential different or additional mechanism, potentially related to vestibular dysfunction.
Blanke et al., 2005 Study:
Methods: Mental own-body transformation task vs. side of space task (control) in healthy adults.
Experiment: Mental own-body transformation task where healthy adults imagined themselves in a position and visual perspective usually reported during spontaneous Out of Body Experiences (OBE).
Finding: Selective activation of the Temporo-Parietal Junction (TPJ) occurred 330-400 ms after stimulus onset in the task. Transcranial Magnetic Stimulation (TMS) interference with the TPJ selectively impaired mental own-body transformations.
Epileptic Patient with OBEs:
Patient: A 22-year-old right-handed female with complex partial seizures originating in the TPJ.
Result: Similar reaction time effects as controls (slower reaction times for front-facing figures). Electrical stimulation in the patient produced results.
Conclusions: OBEs involve double disintegration, affecting personal space and the TPJ.
Easton, Mohr & Blanke (2009):
Participants: Individuals with previous OBEs (n=11) vs. those without (n=36).
Task: Switching between own-body transformation (OBT) task and a mirror task.
Finding: No significant difference in reaction times (RTs) between OBE and non-OBE groups. OBE participants showed reduced accuracy when switching between tasks, especially when the new task involved the usually easier viewpoint.
Conclusion: Fronto-parietal integration is compromised in OBE individuals, implicating both the TPJ and Prefrontal Cortex (PFC) in impaired self-processing.
Summary of OBEs:
Hypothesis: OBEs involve double disintegration, affecting personal space (multisensory integration) and the TPJ.
Role of TPJ and PFC: Implicated in self-processing, agency, Theory of Mind (ToM), and perspective-taking. Frontal lesions have been linked to OBEs.
Study: Easton, Mohr & Blanke (2009) investigated task switching components involving PFC and TPJ, finding greater switch costs for participants with previous OBEs.
Rubber Hand Illusion (RHI):
Definition: Synchronous stroking of a rubber hand and one’s own unseen hand causes the rubber hand to be attributed to one’s own body.
Proprioceptive Drift: Mislocation of the hand during RHI, a measure of illusory ownership.
Experiment: Hypothesis of RHI for the whole body, an experimentally-induced OBE
Experimental Induction of OBEs - Ehrsson (2007):
Procedure: Participants looked at their body from another person’s perspective (behind them) while their actual chest was touched, creating an illusion of an out-of-body experience.
Statements: Participants confirmed the illusion statements related to being outside their body.
SCR (Skin Conductance Response): Measured emotional response when the illusory body was “hurt.”
Conclusion: Perceptual processes, including visual perspective and correlated visual-tactile information, can fully determine the sense of being located inside the body.
