The Hijacked Self: Midbrain and Default Mode Network Functional Patterns in PTSD
Bibliographic record
Abstract
In post-traumatic stress disorder (PTSD), self-related processing disturbances are demonstrated commonly and have been linked to the default mode network (DMN), a large-scale, neural network altered significantly after trauma. However, emerging evidence suggests the midbrain may be underlying self-related processing disturbances as well, yet midbrain systems remain poorly characterized in PTSD. Here, we evaluated midbrain activity and functional connectivity during subliminal, trauma-related stimulus processing (Chapters 2–4), as well as during moral injury-related (MI) memory recall (Chapter 5) in participants with PTSD as compared to healthy controls. Initially, during subliminal, trauma-related stimulus processing, we revealed stronger midbrain periaqueductal gray (PAG) activity among participants with PTSD as compared to healthy controls (Chapter 2). Afterward, we evaluated the functional connectivity exhibited by the PAG, where we revealed stronger functional connectivity between the PAG and the medial prefrontal cortex (mPFC), as well as between the PAG and the precuneus (PCN) among participants with PTSD as compared to healthy controls (Chapter 3). Critically, the mPFC and the PCN are both DMN hubs, which we did not expect to covary functionally with the PAG. Next, we evaluated directionality, where we revealed stronger excitatory functional connectivity directed by the PAG toward the mPFC and toward the PCN among participants with PTSD as compared to healthy controls (Chapter 4). Lastly, during script-driven, MI-related memory recall, we revealed convergent evidence to the above using an independent component analysis (ICA) across participants with civilian-related PTSD, participants with military- or public safety-related PTSD, and MI-exposed, healthy controls. Here, we evaluated the functional network connectivity across the IC correlated most strongly to the DMN. In PTSD, we revealed stronger functional network connectivity exhibited by the PAG across the DMN IC as compared to MI-exposed, healthy controls (Chapter 5). Taken together, these findings suggest the midbrain may be related functionally to the DMN. In PTSD, critically, the DMN appears to be recruited during trauma- and MI-related memory processing, which assists to explain the clinical significance trauma has toward self-related processing and self-identity more generally. Lastly, these findings highlight the importance the midbrain has toward large-scale, neural networks, a long-overlooked dynamic in psychopathology.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".