Talk:Perspective hallucination

Neurological Analysis

Your ‘felt’ position (spatial unity) is located in the temporo-parietal junction (TPJ), and perspective hallucinations arise out of disruption of this system.

“Two patients have been described in whom out-of-body experiences were evoked by electrical stimulation of the right temporoparietal junction.”

“The reviewed data suggest that OBEs are due to functional disintegration of lower-level multisensory processing and abnormal higher-level self-processing at the temporo-parietal junction.”

p. 21 “These data suggest an interaction between lower-level vestibular and multisensory processing and higher-level self-processing such as egocentric visuo-spatial perspective taking, agency, and self-location.”

“We argue that these complex illusory reduplications of one’s own body result from a double disintegration in: (i) personal space; and (ii) between personal and extrapersonal space at the TPJ. The unconscious creation of central representation(s) of one’s own body based on proprioceptive, tactile, visual and vestibular information, and their integration with central representations of extrapersonal space is a prerequisite for rapid and effective action in our surroundings. We speculate that significant ambiguous input from these different sensory systems and, especially the vestibular system, are important mechanisms in the intriguing experience of seeing one’s body in a position that does not coincide with the felt position of one’s body.”

p. 550 “With the use of evoked potential mapping, we show the selective activation of the temporoparietal junction (TPJ) at 330 – 400 ms after stimulus onset when healthy volunteers imagined themselves in the position and visual perspective that generally are reported by people experiencing spontaneous OBEs. Interference with the TPJ by transcranial magnetic stimulation (TMS) at this time impaired mental transformation of one’s own body in healthy volunteers relative to TMS over a control site. No such TMS effect was observed for imagined spatial transformations of external objects, suggesting the selective implication of the TPJ in mental imagery of one’s own body. Finally, in an epileptic patient with OBEs originating from the TPJ, we show partial activation of the seizure focus during mental transformations of her body and visual perspective mimicking her OBE perceptions. These results suggest that the TPJ is a crucial structure for the conscious experience of the normal self, mediating spatial unity of self and body, and also suggest that impaired processing at the TPJ may lead to pathological selves such as OBEs.”

p. 196 “Interestingly, Leube et al. [61] have shown that the TPJ codes multisensory conflict or disintegration between visual and proprioceptive information about one's arm position. Thus, the presence of vestibular and multisensory processing at the lesion site in patients with HAS and OBEs is concordant with the above proposed model of a double disintegration at the TPJ in AP. Neuroimaging studies also support the role of the TPJ in processes of visual perception that can be directly linked to AP. Thus, the TPJ was found to be involved in the perception of several visual aspects of the human body such as the perception of body parts [13], of the entire body (in the extrastriate body area [1,34], and of biological motion [2,46]. Importantly, Astafiev et al. [1] have shown that activity in the extrastriate body area is, not only modulated in a selective fashion by pictures of human bodies or body parts, but also by modifications of a subject's own limb position, suggesting their role in multisensory own body perception and integration. Moreover, mental imagery with respect to one's own body [5,27,55,64] has recently been shown to activate the TPJ [12,102]. This activation was dissociated from activation due to the mental imagery of extrapersonal objects [12,103] and was shown to correlate with phenomenological variables of AP such as illusory self dislocation and visuo-spatial perspective [12]. In addition, Blanke et al. [12] demonstrated that transcranial magnetic stimulation over the TPJ interrupted mental imagery with respect to one's own body but not other objects. In summary, these data show that, in addition to processing at the multisensory level, several areas that are implicated in the visual and cognitive analysis of the entire body of others and of oneself are located at the TPJ. Finally, the TPJ has also been involved in functions of self processing such as egocentric visuo-spatial perspective taking, agency (the feeling of being the agent of one's actions and thoughts), as well as self–other distinction (the capacity by which one distinguishes between oneself and other conspecifics). For instance, the TPJ is the classical lesion site in patients with visuo-spatial neglect [49], a clinical condition, which has been shown to disturb the patient's egocentric spatial relationship with extrapersonal space and visuo-spatial perspective taking. Neuroimaging studies in healthy observers have also revealed activation of the TPJ during egocentric visuo-spatial perspective changes in healthy subjects [88,99]. The pathological visuo-spatial perspectives in OBEs and HAS might thus be related to the functional systems at the TPJ that are involved in the constant updating and calculation of one's visuo-spatial perspective.“