Specific Neural Connection Formation in the Developing Nervous System
Bibliographic record
Abstract
Abstract To construct a properly functioning nervous system, neurons must form precise and specific connections during embryonic development. Many theories have been proposed to explain how connectivity might be established, including the concept of ‘chemoaffinity’, ‘labelled lines’ and ‘segmental pathfinding’. Evidence now shows that each of these theories is best explained by guidance cue and receptor interactions at the growing tip of the neuron, the growth cone. The behaviour of growth cones resulting in the establishment of functional connections is governed by receptor signalling in the growth cone in response to the presence of extracellular guidance cues. The main families of guidance cues include netrins, ephrins, slits and semaphorins, although morphogens also have guidance cue roles. It is the complex arrangement of these cues then that directs axon extension through a series of intermediate targets before growth cones finally recognise their final target and form a synapse. Key concepts: Historical theories of connectivity can be explained by the expression and action of guidance cues and their receptors upon growth cone behaviour. Growth cones are the sensory apparatus of an axon required for proper target identification and formation of functional connections. Disruption of connectivity due to alterations in guidance cue expression during development can result in severe disorders. Guidance through inhibition is the predominant form of growth cone directional control. Molecules traditionally known for their roles in tissue morphogenesis are also found to have important roles as axonal guidance cues.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
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".