Functional motor mapping of domestic pig lumbar spinal cord using penetrating microelectrodes
Bibliographic record
Abstract
The restoration of standing and walking after spinal cord injury (SCI) remains a top priority for individuals with paraplegia. Despite significant advancements in neuromodulation techniques, challenges such as limited selectivity and inconsistent outcomes highlight the need for innovative approaches. Intraspinal microstimulation (ISMS) has emerged as a promising method for restoring motor function as demonstrated in various preclinical models. This study aimed to investigate the functional neural networks within the ventral lumbar spinal cord of pigs. We explored 134 stimulation sites inside the spinal cord in 13 domestic pigs. Post-mortem magnetic resonance imaging (MRI) revealed the location of microelectrode tips inside the spinal cord. The recorded kinematics and electromyographical muscle activity associated with each microelectrode allowed the creation of a functional map of the neural networks activated with ISMS. In addition, we performed anatomical measurements of the lumbar spine and spinal column. Our results revealed a somatotopic organization of motor networks responsible for distinct movements and muscle activations. Differences in activation patterns were primarily observed along the rostrocaudal axis (P < 0.05), where specific stimulation sites were associated with unique movements and muscle responses. In contrast, no notable variations were seen along the mediolateral or dorsoventral directions. Knee extension (KE) was the most frequently observed movement, occurring in 78% of the stimulated sites in the lumbar enlargement, followed by extensor synergy (Ext Syn, 64%), hip flexion (HF, 50%), ankle flexion (AF, 50%), ankle extension (AE, 43%), and hip extension (HE, 43%). Stimulation along the rostrocaudal axis of the lumbar spinal cord elicited a sequence of movements, beginning with HF in the rostral region and transitioning to KE, AF, AE, and HE in the caudal region across animals. Stimulation in the rostral lumbar enlargement produced stronger normalized EMG signals exceeding 50% of the maximum in vastus lateralis (VL) compared to tibialis anterior (TA) gastrocnemius (GS), gluteus medius (GL), and biceps femoris (BF; P < 0.05). Co-activation, defined as simultaneous activity above 50% of normalized maximum EMG activity, occurred at 27.4% of stimulation sites, resulting in synergistic movements and joint stiffening. The resulting map of spinal cord motor networks is important for improving device design and the efficiency of neuroprosthetic interventions. While motor maps exist for other species, they are absent for domestic pigs, a critical model for preclinical testing of SCI treatments. The functional motor maps provided here serve as a foundation for designing and optimizing intraspinal interventions, advancing their translation to clinical application.
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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".