Truths & Myths: Pluralpedia Part 2, Brain Activity in DID
In the fact check, we cover brain activity in switching, brain activity between EPs and ANPs in DID and how this compares to actors trying to imitate having dissociative identities.
All parts exist within one biological body, parts are caused by different brain activity, which means other parts cannot have their own DNA. Moreover, parts do not have physical bodies, any claim to a body is a visualisation tool aiding the part to develop its identity and gain comfort. This visualisation also does not have DNA but that does not mean it cannot be changed. Parts can have different types of relationships though, some parts may consider each other family. This is related to how people have biological or chosen families but in relationships between parts, they reflect those family types rather than actually being those family types.
In the fact check section, we will show studies where actors could not successfully simulate dissociative identities and switch between them. This shows how a person cannot gain dissociative identities by believing they have them or trying to create them by will or want.
Using quantitative electro-encephalogram (QEEG), it was seen that the change between dissociative identities was seen as beta activity (beta waves are high-frequency, low-amplitude brain waves in the awakened state and are involved in conscious thought and logical thinking) in the frontal and temporal lobes. The frontal lobe is responsible for expressive language, voluntary movement and executive functions, which include the ability to plan, organise and self-monitor. [2] The temporal lobes process auditory information and encode memories, they are most associated with these roles. [3]
There have been studies conducted to examine the differences in brain activity between ANPs and EPs in patients with Dissociative Identity Disorder (DID). The terms ANPs and EPs originate from the theory of structural dissociation, which will be discussed in a separate post. In summary, an ANP (apparently normal part) is responsible for carrying out daily tasks, while an EP (emotional part) holds traumatic memories and prevents them from being experienced by the ANPs. Instead, the EPs relive the trauma, rather than being able to experience the present moment like an ANP would. According to this model, EPs are present in patients with PTSD, CPTSD, OSDD, and DID but DID is the only disorder that involves multiple ANPs, setting it apart from the others.
In a study, EPs and ANPs in DID patients were shown angry and neutral faces to observe changes in activity and reaction time to a changing coloured dot on the face. This was compared to a control group of actors attempting to simulate an EP or ANP state. The results showed that EPs in DID patients had higher activity in the right parahippocampal gyrus when presented with either face, compared to DID ANPs. The right parahippocampal gyrus is involved in the recall of autobiographical memories, with a right hemispheric predominance, and is also part of the re-experiencing of symptoms in disorders such as PTSD. This supports the theory that EPs play a role in storing traumatic memories.
The observed activity also suggests and supports the idea that EPs within DID may perceive safe individuals as dangerous and when confronted with reminders of traumatic memories, they may reactivate those memories. While there were other findings in the study, further statistical evidence and a larger sample size are needed to conclude. However, the control group was unable to replicate the activity and reaction time of DID ANPs and EPs. Their reactions were the opposite. When attempting to simulate ANPs and EPs, the actors showed an inverse reaction time and neural brain activity for each state. For example, when the actors were meant to act like ANPs, they tended to react like EPs in DID patients. For ANP-simulating controls neutral faces were salient, they did attract much preconscious attention, as happened for authentic EP. The current findings add to the psychobiological evidence that DID is neither an effect of suggestion and fantasy, nor role-playing.
Additionally, a study was conducted to measure brain perfusion, which refers to the passage of fluid through an organ, normally the delivery of blood to a capillary bed in tissue, during rest. The study compared DID patients to controls and found that DID patients have a higher resting state metabolism, the rate at which calories are used, in the Default Mode Network (DMN), which is active when the person is not focused on the outside world so they are in a resting state such as daydreaming [6], of the brain. This can be explained by the fact that DID patients’ brains are more focused on attending to their self-states during rest, something that the control group did not experience.
Moreover, compared to an EP in DID, ANPs in DID showed more metabolism in the bilateral thalamus, the part of the brain that relays sensory and motor signals and regulates both alertness and consciousness [7]. Furthermore, the study found that EPs in DID have increased regional cerebral blood flow in the primary somatosensory cortex and several motor-related parts of the brain. The primary somatosensory cortex is involved in action planning and execution, indicating that EPs are highly aware of their body being in a threatening situation. This heightened awareness would trigger the need for defensive motor reactions, making it difficult for them to fulfill the instructions for resting.
“Neural processes associated with intended and motivated role-playing of ANP and EP were clearly distinct from those correlated with being ANP and EP following rest instructions.” [1]
Overall, these studies clearly show different alters are due to varying brain activity but also show that DID has a biological backing whose results cannot be replicated through acting or attempting to immediately the presence of dissociative states.
However, it is always important to note that more research should be done with larger samples, but the studies spoken about here at the time of their research were the largest.
Şar V, Dorahy M, Krüger C. Revisiting the Etiological Aspects of Dissociative Identity Disorder: a Biopsychosocial Perspective. Psychology Research and Behavior Management. 2017;Volume 10(10):137-146. doi:https://doi.org/10.2147/prbm.s113743
Queensland Health. Brain Map Frontal Lobes | Queensland Health. www.health.qld.gov.au. Published January 21, 2021.
Queensland Health. Brain Map: Temporal Lobes | Queensland Health. www.health.qld.gov.au. Published January 22, 2021.
Schlumpf YR, Nijenhuis ERS, Chalavi S, et al. Dissociative part-dependent biopsychosocial reactions to backward masked angry and neutral faces: An fMRI study of dissociative identity disorder. NeuroImage: Clinical. 2013;3:54-64. doi:https://doi.org/10.1016/j.nicl.2013.07.002
Schlumpf YR, Reinders AATS, Nijenhuis ERS, Luechinger R, van Osch MJP, Jäncke L. Dissociative Part-Dependent Resting-State Activity in Dissociative Identity Disorder: A Controlled fMRI Perfusion Study. Chao L, ed. PLoS ONE. 2014;9(6):e98795. doi:https://doi.org/10.1371/journal.pone.0098795
Callard F, Margulies DS. What We Talk about When We Talk about the Default Mode Network. Frontiers in Human Neuroscience. 2014;8. doi:https://doi.org/10.3389/fnhum.2014.00619
Tuttle C, Boto J, Martin S, et al. Neuroimaging of Acute and Chronic Unilateral and Bilateral Thalamic Lesions. Insights into Imaging. 2019;10(1). doi:https://doi.org/10.1186/s13244-019-0700-3
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Part one of this series covered DID formation.
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