Dynamic Spatial Tuning of Cervical Muscle Reflexes to Multidirectional Seated Perturbations
Bibliographic record
Abstract
STUDY DESIGN: Human volunteers were exposed experimentally to multidirectional seated perturbations. OBJECTIVE: To determine the activation patterns, spatial distribution and preferred directions of reflexively activated cervical muscles for human model development and validation. SUMMARY OF BACKGROUND DATA: Models of the human head and neck are used to predict occupant kinematics and injuries in motor vehicle collisions. Because of a dearth of relevant experimental data, few models use activation schemes based on in vivo recordings of muscle activation and instead assume uniform activation levels for all muscles within presumed agonist or antagonist groups. Data recorded from individual cervical muscles are needed to validate or refute this assumption. METHODS: Eight subjects (6 males, 2 females) were exposed to seated perturbations in 8 directions. Electromyography was measured with wire electrodes inserted into the sternocleidomastoid, trapezius, levator scapulae, splenius capitis, semispinalis capitis, semispinalis cervicis, and multifidus muscles. Surface electrodes were used to measure sternohyoid activity. Muscle activity evoked by the perturbations was normalized with recordings from maximum voluntary contractions. RESULTS: The multidirectional perturbations produced activation patterns that varied with direction within and between muscles. Sternocleidomastoid and sternohyoid activated similarly in forward and forward oblique directions. The semispinalis capitis, semispinalis cervicis, and multifidus exhibited similar spatial patterns and preferred directions, but varied in activation levels. Levator scapulae and trapezius activity generally remained low, and splenius capitis activity varied widely between subjects. CONCLUSION: All muscles showed muscle- and direction-specific contraction levels. Models should implement muscle- and direction-specific activation schemes during simulations of the head and neck responses to omnidirectional horizontal perturbations where muscle forces influence kinematics, such as during emergency maneuvers and low-severity crashes. LEVEL OF EVIDENCE: N/A.
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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) | 0.001 | 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 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".