A Detached Feel Of Self Associated Amongst Altered Neural Responses To Mirror Touch



Our bodily sense of self contributes to our personal feelings of awareness every bit a witting being. How nosotros come across our bodies too displace through infinite too experience touched yesteryear loved ones are integral parts of our identity. What happens when this sense of self breaks down? One cast of dissolution is Depersonalization Disorder (DPD).1 Individuals amongst DPD experience estranged or disconnected from themselves, every bit if their bodies belong to someone else, too “they” are precisely a detached observer. Or the self feels absent entirely. Other symptoms of depersonalization include emotional blunting, out-of-body experiences, too autoscopy.


Autoscopy for dummies - Antonin De Bemels (cc licence)


Transient symptoms of depersonalization tin displace occur due to stress, anxiety, slumber deprivation, or drugs such every bit hallucinogens (e.g., LSD, psilocybin). These experiences are much to a greater extent than mutual than the official diagnosis of DPD, which occurs inwards only 1-2% of the population.

Research yesteryear Olaf Blanke too colleagues (reviewed inwards Blanke et al., 2015) has tied bodily self-consciousness to the integration of multi-sensory signals inwards fronto-parietal too temporo-parietal regions of the brain.




The fragmentation or loss of an embodied self raises philosophically profound questions. Although the thought of “mind uploading” is preposterous inwards my persuasion (whether via cryonics), proponents must seriously inquire whether the uploaded consciousness volition inwards whatever way resemble the living somebody from whom it arose.2 “Minds are non disembodied logical reasoning devices” (according to Andy Clark).  And...
Increasing prove suggests that the basic foundations of the self prevarication inwards the encephalon systems that stand upwards for the trunk (Lenggenhager et al., 2012).

Lenggenhager et al. asked whether the loss of sensorimotor business office alters trunk ownership too the sense of self. Persons amongst spinal cord injuries scored higher on Cambridge Depersonalization Scale (CDS) items such every bit “I accept to touching myself to construct certain that I accept a trunk or a existent existence.” This suggests that disconnecting the encephalon from somatosensory input tin displace alter phenomenological aspects of self-consciousness.




The Stranger inwards the Mirror

Patients amongst depersonalization non only experience a alter inwards perception concerning the exterior world, but they every bit good accept clear-cut changes concerning their ain body.  ...  The patient sees his confront inwards the mirror changed, stiff too distorted. His ain vocalization seems foreign too unfamiliar to him.  ...  It is inwards this abide by particularly remarkable that the estrangement concerning the exterior globe is oft an estrangement inwards the oculus sphere (Schilder, 1935, p. 139).

Depersonalization tin displace involve perceptual distortions of bodily experience inwards unlike sensory modalities (e.g., vision, hearing, touch, too pain). Recent inquiry has examined interactions betwixt visual too somatosensory representations of self inwards the tactile mirroring prototype (also called visual remapping of touch). Here, the player views images of a somebody existence touched (or not) spell they themselves are touched. Tactile perception is enhanced yesteryear simultaneously receiving too observing the same stimulation, particularly when the icon is of oneself.


Are the symptoms of depersonalization associated amongst reduced or absent responses inwards the tactile mirroring paradigm? If so, at what phase of processing (early or late) does this occur? Influenza A virus subtype H5N1 novel report recorded EEG to facial expression at somatosensory evoked potential (SEP) responses to tactile stimuli during mirroring (Adler et al., 2016). The participants scored high (n=14) or depression (n=13) on the CDS.

One SEP of involvement was the P45, which occurs presently (25-50 msec) after tactile stimulation. Although the spatial resolution of EEG does non allow trouble solid conclusions near the neural generators, nosotros know from invasive studies inwards epilepsy patients too animals that P45 originates inwards the main somatosensory cortex (S1).

When the participants viewed the other-face, P45 did non differ on touching vs. no-touch trials. But the after N80 factor was enhanced for touching vs. no-touch, too the enhancement was like for depression too high depersonalization (DP) participants.



Modified from Figs. iii too four (Adler et al. 2016). SEPs inwards reply to tactile stimuli for depression DP (top) too high DP (bottom) spell observing touching (thick line) or no-touch (thin line) on another person's face. SEPs are shown for components P45 too N80 at a cluster of central-parietal electrodes located over somatosensory cortex.


Results were unlike when subjects viewed images of themselves. P45 was enhanced inwards the depression DP grouping when viewing themselves existence touched (vs. no-touch trials). However, those amongst high DP scores did non demonstrate this P45 enhancement.



Modified from Figs. iii too four (Adler et al. 2016). SEPs inwards reply to tactile stimuli spell observing touching (thick line) or no-touch (thin line) on the participant's own face. Red arrow indicates no self-mirror enhancement of P45.


These results propose a rattling early on disturbance inwards sensory integration of the self inwards depersonalization:
Measurable effects of mirroring for tactile events on the observer's ain confront may hold upwards absent over P45 because deficits inwards implicit self-related processing forbid the resulting visual enhancement of tactile processing from taking house inwards the context of self-related information. An alternative, or additional, explanation for the absence of P45 mirroring effects may hold upwards that seeing their ain trunk causes depersonalised individuals to actively inhibit the processing of bodily stimulation via this pathway. This may crusade feelings of disembodiment, too is akin to the proposition that fronto-limbic inhibitory mechanisms acting on emotional processes crusade the emotional numbing experienced inwards depersonalisation (Sierra too David, 2011).
[Although I'm non too thus certain how much “active inhibition” tin displace occur inside 25 msec...]




Influenza A virus subtype H5N1 after factor (P200) did non demonstrate the expected effect inwards the high DP group, either. While these results are intriguing, nosotros must proceed inwards heed that this was a pocket-size report that requires replication.3


Our Bodies, Our Selves

Predictive coding models hypothesize that the anterior insular cortex (AIC) provides top-down input to somatosensory, autonomic, too visceral regions too plays a critical purpose inwards integrating exteroceptive too interoceptive signals (Seth et al., 2012; Allen et al., 2016). DPD is associated amongst “pathologically imprecise interoceptive predictive signals,” leading to a disruption of witting presence (the subjective sense of reality of the globe too of the self inside the world). Here's the predictive coding model of witting presence (Seth et al., 2012):
It has been suggested that DPD is associated amongst a suppressive machinery grounded inwards fronto-limbic encephalon regions, notably the AIC, which “manifests subjectively every bit emotional numbing, too disables the procedure yesteryear which perception too knowledge larn emotionally colored, giving ascent to a subjective feeling of unreality” (Sierra too David, 2011)...

In our model, DPD symptoms correspond to abnormal interoceptive predictive coding dynamics. ... the imprecise interoceptive prediction signals associated amongst DPD may resultant inwards hypoactivation of AIC since at that topographic point is an excessive but undifferentiated suppression of mistake signals.

In contrast, Adler et al. (2016) adopt a rattling unlike (Freudian) view:
We speculate that the abnormalities related to depersonalisation may hold upwards based on a lack of mirroring interactions inwards early on childhood. Several recent papers culminated inwards the thought that mirroring experiences inwards early on life - the procedure of moving too existence moved yesteryear others, both physically too affectively - hand ascent to our sense of bodily self... This bodily self forms the heart of other forms of self-consciousness, from trunk ownership to the sense of means too the might to mentalise (e.g. Fonagy et al., 2007; Gallese & Sinigaglia, 2010; Markova too Legerstee, 2006; Stern, 1995). ...  Depersonalisation could hold upwards a potential number of such developmental experiences.

I don't purchase it... none of the participants inwards their report had a clinical diagnosis, too nosotros know nix of their early on childhood. In the end, whatever model of chronic DPD nevertheless has to trouble organisation human relationship for the transient phenomena of disconnection too unreality experienced yesteryear too thus many of us.


Further Reading

Feeling Mighty Unreal: Derealization inwards Kleine-Levin Syndrome

Fright Week: The Stranger inwards the Mirror


Footnotes

1 In DSM-5, the syndrome is known every bit blog post.

2 For a tidings of the relevant issues, come across The False Science of Cryonics too Silicon soul: The vain dream of electronic immortality.

3 Given the requirements for specialized equipment too a specialized population, I don't imagine this report is on the Many Labs or Replication Project lists.


References

Adler, J., Schabinger, N., Michal, M., Beutel, M., & Gillmeister, H. (2016). Is that me inwards the mirror? Depersonalisation modulates tactile mirroring mechanisms. Neuropsychologia DOI: 10.1016/j.neuropsychologia.2016.03.009

Allen M, Fardo F, Dietz MJ, Hillebrandt H, Friston KJ, Rees G, Roepstorff A. (2016). Anterior insula coordinates hierarchical processing of tactile mismatch responses. Neuroimage 127:34-43.

Blanke O, Slater M, Serino A. (2015). Behavioral, Neural, too Computational Principlesof Bodily Self-Consciousness. Neuron 88(1):145-66.

Lenggenhager, B., Pazzaglia, M., Scivoletto, G., Molinari, M., & Aglioti, S. (2012). The Sense of the Body inwards Individuals amongst Spinal Cord Injury. PLoS ONE, 7 (11) DOI: 10.1371/journal.pone.0050757

Schilder, P. (1935). The Image too Appearance of the Human Body. London: Kagan, Paul, Trench, Trubner & Co.

Seth AK, Suzuki K, Critchley HD. (2012). An interoceptive predictive coding model of witting presence. Front Psychol. 2:395.





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