A complex reach direction rule that delays reaction time causes alternating excitation and inhibition in express muscle responses and corticospinal excitability
Notice bibliographique
Résumé
ABSTRACT The dynamics of muscle activation during fast visually guided reaching are suggestive of two neural control signals; an early signal that acts at “express” latencies in response to the visual stimulus, and a longer latency signal that executes a strategic reach plan. Here we developed a task designed to temporally isolate the express visuomotor response from the longer latency muscle response, and to characterize the time course of corticospinal excitability changes in the express response time window when the late voluntary response is delayed. We tested this by measuring electromyograms (EMG) and changes in Motor Evoked Potential (MEP) amplitudes following Transcranial Magnetic Stimulation (TMS) of the motor cortex, as participants reached either towards or away from visual targets. Crucially, the information about the task rule was provided by the luminance of the target itself, and so was unknown to the subject until the instant of target presentation. This feature delayed reaction times, likely because additional (presumably cortical) processing was required to interpret and apply the rule before formation of a goal directed reach plan. The earliest EMG responses to target presentation occurred with a 70-105 ms time window, and were oriented to bring the hand toward the location of the target. However, there was also a slightly later response that was also time-locked to target appearance in a 105-140 ms time window. This second response was “reciprocal” to the first, such that it was oriented to take the hand in the direction opposite from the target. In some participants, additional oscillating cycles were apparent after the first two target-related responses. These multiphasic express visuomotor responses were nearly identical in both pro- and anti-reach conditions. These muscle activity responses were generally reflected in the temporal pattern of corticospinal excitability modulations in experiment two. Indeed, the MEP and background EMG responses showed an alternating pattern similar to that in experiment one, although the effect was clearer in the anti-reach than the pro-reach condition. Overall, the data show that the express and voluntary responses are indeed distinct neural control signals, which supports the hypothesis that at least two separate neural pathways (one slow and one fast) contribute to the control of visually guided reaching. The properties of the fast pathway are consistent with a tecto-reticulospinal pathway, while those of the slow pathway are consistent with a transcortical loop.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».