The Transformation of a Unilateral Locomotor Command into a Symmetrical Bilateral Activation in the Brainstem
Bibliographic record
Abstract
A unilateral activation of the mesencephalic locomotor region (MLR) produces symmetrical bilateral locomotion in all vertebrate species tested to date. How this occurs remains unresolved. This study examined the possibility that the symmetry occurred at the level of the inputs from the MLR to reticulospinal (RS) cells. In lamprey semi-intact preparations, we recorded intracellular responses of pairs of large, homologous RS cells on both sides to stimulation of the MLR on one side. The synaptic responses on both sides were very similar in shape, amplitude, and threshold intensity. Increasing MLR stimulation intensity produced a symmetrical increase in the magnitude of the responses on both sides. Ca(2+) imaging confirmed the bilateral activation of smaller-sized RS cells as well. In a high-divalent cation solution, the synaptic responses of homologous RS cells persisted and exhibited a constant latency during high-frequency stimulation. Moreover, during gradual replacement of normal Ringer's solution with a Ca(2+)-free solution, the magnitude of responses showed a gradual reduction with a similar time course in the homologous RS cells. These results support the idea that the MLR projects monosynaptically to RS cells on both sides with symmetrical inputs. During locomotion of the semi-intact preparation, the discharge pattern was also very similar in homologous bilateral RS cells. Anatomical experiments confirmed the presence of MLR neurons projecting ipsilaterally to the reticular formation intermingled with neurons projecting contralaterally. We conclude that the bilaterally symmetrical MLR inputs to RS cells are likely contributors to generating symmetrical locomotor activity.
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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".