Cerebral circuits involved in preferential hand posture representation for action
Bibliographic record
Abstract
OBJECTIVE: The thumb-down/fingers-up (standard) posture was shown to be the configuration in which the hand is preferentially represented by the brain. This supra-modal representation results in improved sensorimotor performances. This study aims at identifying the cortical circuit responsible for this advantage. METHODS: Different TMS coil orientations (antero-posterior, latero-medial, postero-anterior) - activating different cortical circuits- have been used to test cortico-spinal and cortico-cortical connections in different postures. Additionally, pair-pulse TMS protocols were used to explore inhibitory and facilitatory mechanisms within the primary motor cortex (M1) that might contribute to the observed postural advantage. RESULTS: A significant corticospinal excitability difference in nMEPs between standard and inverse posture was observed with antero-posterior TMS (p = 0.003), activating cortico-cortical connections from premotor cortex (PM) and with postero-anterior TMS (p = 0.042), favoring local cortical connections. Latero-medial stimulation, activating direct corticospinal connections, did not show a preference. A MEPs analysis further revealed a significant effect exclusively for antero-posterior stimulation (p < 0.003). Intracortical facilitation and inhibition were unaffected by hand postures. CONCLUSIONS: The postural advantage of the thumb-down/fingers-up hand configuration is associated with a neural circuit involving PM cortex projecting to M1, activated by antero-posterior and postero-anterior TMS. SIGNIFICANCE: The corticospinal evoked activity to different TMS protocols gave cues on the neural basis of body representation and favored posture.
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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 | 0.001 |
| 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) | 0.004 | 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".