Persistent inward currents in motoneuron dendrites: Implications for motor output
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The dendrites of motoneurons are not, as once thought, passive conduits for synaptic inputs. Instead they have voltage-dependent channels that provide the capacity to generate a very strong persistent inward current (PIC). The amplitude of the PIC is proportional to the level of neuromodulatory input from the brainstem, which is mediated primarily by the monoamines serotonin and norepinephrine. During normal motor behavior, monoaminergic drive is likely to be moderately strong and the dendritic PIC generates many of the characteristic features of motor unit firing patterns. Most of the PIC activates at or below recruitment threshold and thus motor unit firing patterns exhibit a linear increase just above recruitment. The dendritic PIC allows motor unit derecruitment to occur at a lower input level than recruitment, thus providing sustained tonic firing with little or no synaptic input, especially in low-threshold units. However the dendritic PIC can be readily deactivated by synaptic inhibition. The overall amplification due to the dendritic PIC and other effects of monoamines on motoneurons greatly increases the input-output gain of the motor pool. Thus the brainstem neuromodulatory input provides a mechanism by which the excitability of motoneurons can be varied for different motor behaviors. This control system is lost in spinal cord injury but PICs nonetheless recover near-normal amplitudes in the months following the initial injury. The relationship of these findings to the cause of the spasticity syndrome developing after spinal cord injury is discussed.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.000 | 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 it