Time course of corticospinal excitability in a simple reaction time task
Bibliographic record
Abstract
The production of movement in a simple reaction time (RT) task can be separated into two time periods: the foreperiod, which is thought to include preparatory processes, and the RT interval, which includes initiation processes. To better understand these processes, transcranial magnetic stimulation (TMS) has been used to probe the level of corticospinal excitability (CE) at various time points during response preparation and initiation. Previous research has shown that CE decreases as the imperative stimulus (IS) approaches and increases once the IS has been presented; however these two time frames have been examined independently. As CE during the entirety of the process of movement production has not been described, the purpose of this study was to measure when and at what rate changes in CE occur during both the foreperiod and RT interval, relative to a true baseline level. Participants performed a button press movement in the context of a RT task and CE was measured using TMS at 21 time points, encompassing both the 1500 ms fixed foreperiod and the RT interval. Furthermore, a baseline measure was taken prior to the warning stimulus (WS) when the participant was at rest. Results indicated that during the foreperiod CE levels quickly increased from baseline with the presentation of the WS. This was followed by a period of stable CE, and by a subsequent decline in the 500 ms leading up to the IS. This decline was followed by a rapid increase in CE following the go-signal as the movement is initiated. Importantly, even though levels of CE decreased prior to the IS, this does not reflect a decrease in preparatory activation, but rather is thought to reflect selective inhibitory control mechanisms that function to avoid early (premature) response initiation.Acknowledgments: Supported by NSERC
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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 | 0.004 |
| 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".