The first study is a literature review of neuroimaging studies on general dissociative disorders. DID itself has the smallest section of the paper, with only 2 paragraphs and no figures. They say right off the gate that neuroimaging studies of DID have inconsistent results and end the section with a study that finds no functional difference in working memory between DID patients and healthy controls. The only relevant supporting study cited found abnormal fluctuations in cerebral blood flow, around the orbitofrontal cortex which actually looks legit.
The second study was designed to test a new empirical measurement of integration for tracking the progress of DID treatment. Only 11 participants, all female, heavily relied on self-report with only a little observational inference. Quality of study aside, it has little to do with the question at hand (neurological/psychological basis of DID), and its main finding is that integration might not be linked to time in therapy.
Third study was a comparison of hippocampal volume between patients with DID, PTSD, and healthy controls. The study found decreased volume as well as abnormal anatomy of hippocampus in DID patients compared to the controls, particularly in the CA2 and CA4-DG region. The CA2 region is responsible for
time processing and social memory, while the CA4-DGregion is responsible for
spacial awareness and plays a role in pattern recognition. While this does show a significant difference in neuroanatomy in DID patients, the study is limited to the hippocampus, which mainly tells us about spacial awareness and some aspects of working memory. This lends credence to the idea of dissociative amnesia, but, frankly, that's not what's being called into question.
The fourth paper is a case study of a woman who claims she can voluntary and rapidly switch between alters. Ever word of that last sentence raises massive red flags on its credibility. They found activation primarily in sensory-motor areas of the brain (due to the subject scrunching her face when "switching"), as well as activation in the nucleus accumbens, which plays a role in the reward and reinforcement system. Given that they didn't report any other changes in brain function, I'd say this finding is more consistent with Munchhausen's than anything else. I wonder if other scientists laugh at these researchers behind their backs?
The last paper is the most legitimate source, and I don't see any glaring issues with it. An fMRI scan of diagnosed DID patients found significant increase in activity around the temporal gyrus, dorsomedial prefrontal cortex, and the orbitofrontal cortex, which handles
auditory/language processing,
sense-of-self, and
context-specific responding, respectively. Pretty much exactly what you'd expect if you're assuming DID is true. I'll go over this one closer later, but it looks like I'll have to mark this one as legitimate.