Joint Anatomical, Histological, and Imaging Investigation of the Midbrain Target Region for Superolateral Medial Forebrain Bundle Deep Brain Stimulation
Bibliographic record
Abstract
INTRODUCTION: Deep brain stimulation (DBS) of the superolateral branch of the medial forebrain bundle (slMFB) is currently being researched in clinical trials and open case series as a therapeutic option for treatment-resistant major depressive disorder and treatment-resistant obsessive-compulsive disorder (TR-OCD). There are numerous publications describing stimulation in such proximity to the ventral tegmental area (VTA) and open questions remain concerning the stimulation target and its functional environment. As of right now, we are not aware of any publications that compare the typical electrode placements with the histologically supported tractographic depiction of the target structure. METHODS: We used three cadaver midbrain samples with presumed unaltered anatomy. After fixation, staining and slicing, the histological samples were warped to the Montreal Neurological Institute (MNI) big brain environment. Utilizing a tractographic atlas, a qualitative analysis of the typical slMFB stimulation site in the lateral VTA utilizing a subset of clinically implanted DBS electrodes in n = 12 patients, successfully implanted for TR-OCD was performed. RESULTS: A joint qualitative overlay analysis of predominantly tyrosine hydroxylase stained histology at different resolutions in an anatomical common space was achieved. Localization of the DBS lead bodies was found in the typical positions in front of the red nuclei in the lateral VTA. DBS lead tip region positions explained the oculomotor side effects of stimulation related to paranigral or parabrachial pigmented sub-nuclei of the VTA, respectively. The location of active electrode contacts suggests downstream and antidromic effects on the greater VTA related medial forebrain bundle system. CONCLUSION: This is the first dedicated joint histopathological overlay analysis of DBS electrodes targeting the slMFB and lateral VTA in a common anatomical space. This analysis might serve to better understand the DBS target region for this procedure. INTRODUCTION: Deep brain stimulation (DBS) of the superolateral branch of the medial forebrain bundle (slMFB) is currently being researched in clinical trials and open case series as a therapeutic option for treatment-resistant major depressive disorder and treatment-resistant obsessive-compulsive disorder (TR-OCD). There are numerous publications describing stimulation in such proximity to the ventral tegmental area (VTA) and open questions remain concerning the stimulation target and its functional environment. As of right now, we are not aware of any publications that compare the typical electrode placements with the histologically supported tractographic depiction of the target structure. METHODS: We used three cadaver midbrain samples with presumed unaltered anatomy. After fixation, staining and slicing, the histological samples were warped to the Montreal Neurological Institute (MNI) big brain environment. Utilizing a tractographic atlas, a qualitative analysis of the typical slMFB stimulation site in the lateral VTA utilizing a subset of clinically implanted DBS electrodes in n = 12 patients, successfully implanted for TR-OCD was performed. RESULTS: A joint qualitative overlay analysis of predominantly tyrosine hydroxylase stained histology at different resolutions in an anatomical common space was achieved. Localization of the DBS lead bodies was found in the typical positions in front of the red nuclei in the lateral VTA. DBS lead tip region positions explained the oculomotor side effects of stimulation related to paranigral or parabrachial pigmented sub-nuclei of the VTA, respectively. The location of active electrode contacts suggests downstream and antidromic effects on the greater VTA related medial forebrain bundle system. CONCLUSION: This is the first dedicated joint histopathological overlay analysis of DBS electrodes targeting the slMFB and lateral VTA in a common anatomical space. This analysis might serve to better understand the DBS target region for this procedure.
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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 | 0.001 | 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".