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Me and My Unpleasant Shadow—A Substrate for Paranoia and Outside Control?

21 September 2006. Paranoia and the sense that others are controlling one’s thoughts and actions are prominent in many people with schizophrenia, but there is little understanding of what underlies these symptoms. A short case report in today’s issue of Nature offers a serendipitous clue about one brain region that may be involved. Olaf Blanke of the École Polytechnique Fédérale of Lausanne, Switzerland, and colleagues report that electrical stimulation at the junction between the temporal and parietal lobes in an awake patient evoked a sensation of a shadow person, who mirrored the patient’s movements.

First author Shahar Arzy and colleagues write that the 22-year-old woman was being evaluated for possible surgery to treat epilepsy when she reported a person mirroring her body position, but just outside it. At that moment, the researchers were stimulating in the border zone of the temporal and parietal lobes, an area that has been found to integrate sensory information to help create accurate perceptions of the body and self (see also Arzy et al., 2006).

When the patient sat up and embraced her knees, the shadow person seemed to embrace her, and it was not a pleasant experience. Even more interesting, when she sorted cards, the authors write, she reported the shadow person interfering with her: “He wants to take the card. He doesn’t want me to read.”

The authors note that Chloe Farrer of Institut des Sciences Cognitives in Lyon, France, and colleagues have linked hyperactivity in temporoparietal cortex with the misattribution of agency in patients with schizophrenia (Farrer et al., 2004). “Although our patient was aware of the similarity between her own postural and positional features and those of the illusory person, she did not recognize that that person was an illusion of her own body, like many deluded schizophrenic patients,” the authors write.—Hakon Heimer.

Reference:
Arzy S, Seeck M, Ortigue S, Spinelli L, Blanke O. Induction of an illusory shadow person. Nature. 2006; Sep 21. Abstract

 
Comments on News and Primary Papers
Comment by:  Carol Tamminga, SRF Advisor
Submitted 21 September 2006 Posted 21 September 2006

There is an interesting old neurosurgury literature that shows findings like this. The limitation is that the findings are always in single patients, and hard to interpret because one cannot do real manipulations. An interesting follow-up would be some kind of research using TMS.

View all comments by Carol Tamminga


Comment by:  Avi Peled
Submitted 29 September 2006 Posted 29 September 2006

You do not need fancy direct brain stimulation to fool the brain into illusion or delusion-like activity. You can use external (indirect) manipulations. Examples are many: the “McGurk effect,” where conflicting auditory-visual stimuli cause fusion effects to make patients hear something that is not there, and the rubber hand illusion initially described by Botvinik and Cohen (1) and replicated by us (2) in schizophrenia patient literature and later imaged with EEG (3).

More interestingly, this finding adds to the growing knowledge that mental disorders can be reconceptualized as disorders of brain organization (4). It is about time that psychiatrists start to build a brain-related diagnostic system, even if it is currently hypothetical. The benefits of such a diagnostic system are detailed in a dedicated website for the future of psychiatry; see www.brainoptimizers.org.

References:

1. Botvinick M, Cohen J. Rubber hands 'feel' touch that eyes see. Nature. 1998 Feb 19;391(6669):756. Abstract

2. Peled A, Ritsner M, Hirschmann S, Geva AB, Modai I. Touch feel illusion in schizophrenic patients. Biol Psychiatry. 2000 Dec 1;48(11):1105-8. Abstract

3. Peled A, Pressman A, Geva AB, Modai I. Somatosensory evoked potentials during a rubber-hand illusion in schizophrenia. Schizophr Res. 2003 Nov 15;64(2-3):157-63. Abstract

4. Peled A. Brain profiling and clinical-neuroscience. Med Hypotheses. 2006;67(4):941-6. Epub 2006 May 15. Abstract

View all comments by Avi Peled


Comment by:  Daniel Wolf
Submitted 6 October 2006 Posted 6 October 2006
  I recommend the Primary Papers

I wonder whether temporoparietal dysfunction and the phenomenon reported in this paper may relate to auditory hallucinations. It seems that sensing a "shadow person" might dramatically increase the tendency to misattribute inner speech to an outside source.

View all comments by Daniel Wolf


Comment by:  Chloe Farrer
Submitted 19 December 2006 Posted 19 December 2006

One important comment to make when one compares the study of Blanke and colleagues with our study (Farrer et al., 2004) is that we scanned patients while they were not experiencing any delusion of control, although patients were selected on the basis of their symptoms (they had a high delusion of control score). Our approach was complementary to the one of Spence and colleagues (Spence et al., 1997, who scanned patients while they were experiencing a delusion of control. These authors found hyperactivation of the right inferior parietal lobule (IPL) when patients were moving a joystick and also experienced a delusion of control. IPL was much less activated when the same patients were scanned a few months after, while they were doing the same task but did not experience any delusion. By consequence, these studies show that abnormal activation either artificially induced (like in the stimulation study) or pathologically...  Read more


View all comments by Chloe Farrer
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