Functional hippocampal redundancy as a measure of resilience to pathological aging
Bibliographic record
Abstract
Aging is accompanied by declines in episodic memory and altered hippocampal function, each of which are exacerbated in response to the development of Alzheimer’s disease. Therefore, it is critical to identify factors which support resilience to such pathological aging. One proposed factor is redundancy, the existence of duplicate elements within a system that offers protection against failure. Redundancy is hypothesized to operate within the brain as a neuroprotective mechanism, though this hypothesis has not been tested in the context of neurodegenerative diseases. This dissertation presents initial evidence that hippocampal redundancy, quantified from resting-state functional brain networks, operates as a neuroprotective mechanism in aging.The role of hippocampal functional redundancy is examined in the context of clinical, cognitive, pathological, and experiential factors across three studies. The first study demonstrates that posterior hippocampal redundancy is lower in mild cognitive impairment, a precursor stage to Alzheimer’s disease, than in healthy aging, though redundancy does not differ between early and late stages of mild cognitive impairment. Further, posterior hippocampal redundancy is related to better memory performance. The second study expands upon these results, relating hippocampal redundancy to pathological markers of Alzheimer’s disease, showing that hippocampal redundancy mediates the relationship between hippocampal volume and memory performance. Additionally, the combination of low hippocampal redundancy, volume, and memory is associated with subsequent dementia conversion. The final study reveals that the positive mnemonic benefit of redundancy weakens throughout healthy older adulthood and is specific to posterior rather than anterior hippocampus. However, this study finds no evidence that redundancy is influenced by either education or physical activity, two prominent protective factors for healthy aging.Across these three studies, hippocampal redundancy, particularly in posterior regions, is shown to be associated with better clinical and cognitive outcomes. Future studies will benefit from longitudinal analysis of redundancy in relation to clinical progression and long-term measures of physical activity. Together, the results presented in this dissertation provide the initial evidence that hippocampal redundancy supports resilience to pathological aging.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.001 |
| 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".