Thalamocortical projections to the premotor cortex (PM) following unilateral lesion of primary motor cortex (M1) in macaque monkeys
Bibliographic record
Abstract
Voluntary movements, such manual dexterity with independent use of fingers, strongly depend on the corticomotoneuronal projection system in primates. Furthermore, the cortico-basal ganglia-thalamo-cortical and cortico-cerebello-thalamo-cortical loops contribute to shape motor commands for manual dexterity. The thalamocortical (TC) projections to multiple motor cortical areas represent a crucial terminal projection step underlying these two subcortical influences. The present study aimed at investigating whether the TC projection terminating in premotor cortex (PM) is affected following a lesion restricted to the homolateral primary motor cortex (M1) in adult macaque monkeys. The TC projections to PM were compared between intact monkeys (n=3) and monkeys subjected to a unilateral lesion of the homolateral M1 hand area (n=7), using the biotinylated dextran amine (BDA) retrograde tract-tracing method. The group of 7 lesioned monkeys was subdivided into a subgroup of 4 untreated subjects, while a subgroup of 3 subjects was treated with an anti-Nogo-A antibody. The BDA retrogradely labelled TC neurons projecting to PM were charted and quantified across different thalamic nuclei. The absolute total numbers of TC-stained neurons were considered for further analysis and inter-subgroups' comparison. As compared to intact monkeys, the TC projections' density in M1 lesion untreated monkeys was strongly reduced (about 6x less). In the anti-Nogo-A antibody treated subgroup (also M1 lesioned), the density of TC projection was less reduced (about 3x), as compared to intact monkeys. To minimize interindividual variability related to BDA injection sites' properties, the numbers of TC-stained neurons were normalized in each monkey based on the numbers of BDA labelled corticospinal (CS) axons. The normalization yielded comparable results as the absolute TC numbers, with however a more pronounced, actually complete separation between the 3 respective ranges of data points corresponding to the 3 monkeys' subgroups. In conclusion, the M1 lesion induced a sharp downregulation of TC projections to the homolesional PM, which was moderately minimized by the anti-Nogo-A antibody treatment.
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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".