Spinal dI3 neurons are involved in sustained motor adaptation elicited by low-threshold cutaneous afferents
Bibliographic record
Abstract
ABSTRACT Adaptation of muscle activity to meet a certain target or intention is traditionally attributed to supraspinal structures. However, evidence is mounting that this process can occur within the spinal cord through intrinsic plasticity and circuit reorganization. Here, we investigate the role of a class of excitatory spinal interneurons, called dorsal interneuron 3 (dI3), in the acquisition of novel motor behaviors independent of supraspinal input. Using a real-time closed-loop stimulation paradigm in spinalized mice, we promoted a persistent adaptation in the hindlimb position to be higher than its resting level by delivering saphenous nerve stimulation contingent on toe elevation. The stimulation intensities were calibrated to selectively recruit low-threshold mechanoreceptors (LTMRs). To test the contribution of dI3s in this motor adaptation, inhibitory DREADD (hM4Di) receptors were expressed in Isl1⁺/Vglut2⁺ cells, achieving reversible, cell-type-specific silencing of dI3s. Our results demonstrate that stimulation of cutaneous inputs to the spinal cord contingent on a certain positional goal can generate sustained changes in motor activity, in this case, in the form of elevation of toe position above a preset vertical threshold. Chemogenetic silencing of dI3s abolished this motor adaptation induced by activation of LTMRs. These findings indicate that dI3 activity is essential for a particular type of motor adaptation driven primarily by LTMR input. NEW & NOTEWORTHY We developed a real-time, closed-loop stimulation paradigm in spinalized mice using kinematic video tracking to trigger electrical stimulation of the saphenous nerve. We discovered that low-threshold stimulations targeting non-nociceptive cutaneous afferents can elicit sustained motor adaptations independently from supraspinal input. Furthermore, using two chemogenetic techniques to transiently inhibit a population of spinal neurons, called dI3s, we found that these neurons are crucial for integrating these low-threshold stimuli to elicit sustained changes in motor behaviour.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.002 |
| 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".