Hypovolemia affects cortical activity patterns associated with the cardiovascular response to moderate lower body negative pressure (LBNP)
Bibliographic record
Abstract
We tested the hypothesis that hypovolemia (HV; reduced blood volume) modifies the cortical autonomic network (CAN) response to moderate (−35 mmHg) LBNP. CAN activity was assessed using functional magnetic resonance imaging (fMRI) with blood oxygen level‐dependent (BOLD) contrast in young healthy subjects (n = 9). Testing was repeated under normovolemia (NV) and HV (spironolactone: 100mg/day for 3 days; randomized). BOLD data were collected at baseline and during 3 repeated 60s bouts of LBNP (separated by 90s rest periods). Random effects analysis revealed BOLD signal changes (p < 0.005, uncorrected) in the CAN during both the onset (baroreceptor unloading) and offset (baroreceptor loading) phases of LBNP. In both NV and HV, LBNP onset induced CAN BOLD signal changes in the thalamus, hippocampus, putamen, mid‐cingulate cortex and posterior insular cortex. In addition, LBNP onset in HV also elicited BOLD signal changes in the caudate nucleus, and anterior and posterior cingulate cortex. Changes in these additional areas were observed again during HV offset, although HV offset did not elicit a change in hippocampal activation. Compared to NV, these results suggest that HV was associated with more widespread CAN activation during the dynamic phases of baroreceptor manipulation. Supported by the Canadian Space Agency.
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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) | 0.001 | 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".