Single‐axon tracing study of corticostriatal projections arising from primary motor cortex in primates
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 axonal projections arising from the forelimb area of the primary motor cortex (M1) in cynomolgus monkeys (Macaca fascicularis) were studied following microiontophoretic injections of biotinylated dextran amine under electrophysiological guidance. The microinjections were centered on layer V, and 42 anterogradely labeled corticofugal axons were reconstructed from serial frontal or sagittal sections with a camera lucida. Our investigation shows that the primate striatum receives both direct and indirect projections from M1. The direct corticostriatal projection is formed by axons that remain uniformly thin and unbranched throughout their sinuous trajectory to the ipsilateral striatum. They divide as they enter the dorsolateral sector of the post-commissural putamen, the so-called sensorimotor striatal territory. The indirect corticostriatal projection derives from a thin collateral emitted within the corona radiata by thick, long-range fibers that descend toward the brainstem. The collateral enters the putamen dorsomedially and remains unbranched until it reaches the dorsolateral sector of the putamen, where it breaks out into two to four axonal branches displaying small and equally spaced varicosities. Both direct and indirect corticostriatal axons branch moderately but occupy vast rostrocaudal striatal territories, where they appear to contact en passant several widely distributed striatal neurons. These findings reveal that, in contrast to current beliefs, the primate motor corticostriatal system is not exclusively formed by axons dedicated solely to the striatum. It also comprises collaterals from long-range corticofugal axons, which can thus provide to the striatum a copy of the neural information that is being conveyed to the brainstem and/or spinal cord.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| 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) | 0.000 | 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