IC‐P‐049: AMYLOIDOSIS CHANGES ASSOCIATIONS BETWEEN HIPPOCAMPUS VOLUME AND BRAIN METABOLIC DECLINES
Bibliographic record
Abstract
The cerebral metabolic rate of glucose measured by Positron Emission Tomography (PET) using [18 F]FDG is often used as a biomarker of neurodegeneration in Alzheimer's disease (AD) and healthy aging. Mechanism underlying hypometabolism in these populations has been attributed to brain amyloidosis, tauopathy or cell depletion. Here, we investigate the link between hippocampal volume and regional hypometabolism in normal and an AD animal model (transgenic rat McGill-R-Thy1-APP) harbouring brain amyloidosis. This model shows the effects of amyloidosis on biomarkers in the absence of tauopathy or cell depletion. We hypothesized a distinct association pattern between rate of metabolic decline in hippocampal projections and hippocampal volume in TG animals. A total of 15 rats with a mean age of 16.6 months were used for this study. Hippocampus volumes were computed using structural Magnetic Resonance Imaging (MRI). The images [18F]FDG were acquired using PET at baseline and follow-up. Then the percent change of FDG values were calculated with respect to the baseline values. Whole brain images were obtained by MRI using Fast Imaging with Steady State Precession. PET images were then correlated at a voxel level with the hippocampus volume from the MRI images. In WT, average volumes in total brain and hippocampus (mm3) at baseline were 2418.91 ± 142.68 and 78.76 ± 5.98, respectively. In TG, average volume in total brain and hippocampus were 2390.31 ± 210.00 and 81.68 ± 8.28, respectively. In WT, average follow-up total brain volume and hippocampus were 2454.45 ± 131.99 and 76.9875 ± 2.67, respectively; and 2392.13 ± 208.64 and 75.48 ± 8.75, respectively in TG. Changes in FDG and hippocampal volume in WT were -0.72 ± 6.7% and 5.3 ± 5.0%, respectively and in TG were 6.1 ± 11% and 6.2 ± 3.4%, respectively. In WT, 6-month hypometabolism in frontal, temporal, cingulate cortex and striatum were associated with individual baseline hippocampal volumes. In TG, 6-month hypometabolism in the amygdala, basal forebrain, cingulate cortex and striatum were associated with individual baseline hippocampal volumes.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".