Modulation of the carotid baroreflex using a novel, low-cost, low-noise, MRI-safe variable-pressure neck chamber system
Bibliographic record
Abstract
Modulation of the carotid baroreflex can be performed in research, teaching, and clinical settings using variable-pressure neck chambers. However, there are only a small number of commercially available systems, which are expensive. Furthermore, most systems are not compatible with magnetic resonance imaging (MRI), as they contain metallic components or are too bulky to fit within the MRI bore. Therefore, the purpose of the present project was to develop a variable-pressure neck chamber system for less than $1500 USD using commonly sourced parts that are MRI-compatible. The components of our variable-pressure neck chamber system consisted of an AC/DC converter, diaphragm pump, timer, solenoid valves (S/V), acrylonitrile butadiene styrene (ABS) pipe, swimming goggles, pneumatic kill switch, and voltage regulator, all sourced from common hardware suppliers or Amazon.ca. The assembled system fits on a 51 x 71 cm (20 x 28 in) table surface and weighs ~8 kg (~18 lb.). The sourced goggles (neck chambers) and pneumatic kill switch were made from plastic compounds, permitting safe use within an MRI. All supplies purchased to construct this system totaled <$1,200 USD. Solenoid valve position duration and cycle count (open-closed = one cycle) were programmed independently through the timer and wired to a trigger switch to enable users to easily adjust stimulus duration and frequency and activate the system with a single button press. Performance tests consisted of applying localized positive and negative pneumatic pressures (20 s stimulus duration) to the carotid sinuses through a range from +60 to -60 mmHg in steps of 20 mmHg. The data indicate our variable-pressure neck chamber system is capable of delineating a stimulus-response relationship for both the blood pressure (decrease: -6±1 mmHg, increase: 9±3 mmHg, range: -7 to 13 mmHg) and the heart rate (decrease: -9±2 bpm, increase: 12±3 bpm, range: -10 to 15 bpm) components of the baroreflex. Technical data reveal the system operates quietly (34.0±1.50 dB) and fast with an evacuation rate of 385±35 mmHg/s during suction application and 371±175 mmHg/s during pressure application. The present study demonstrates the successful development of a low-cost, low-noise, MRI-safe variable-pressure neck chamber system built with easily sourced parts. Future design iterations will achieve higher evacuation rates, greater portability, and integrate automated R-wave gated stimulus application. Funding: NSERC Discovery Grant (#05323) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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) | 0.000 | 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 teacher head, 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".