Author response: AMPK acts as a molecular trigger to coordinate glutamatergic signals and adaptive behaviours during acute starvation
Bibliographic record
Abstract
Animals often need to adapt to changes in food availability in order to survive. When food is in short supply and animals are starving, their energy reserves are low. To conserve energy, behaviours that are not essential to survival, like mating, are put on hold. Instead, animals channel their energies into foraging strategies that may help them find new food sources. These behavioural changes are likely to be caused by changes in brain activity triggered by starvation. It is not entirely clear how starvation changes the brain and consequently how an animal behaves. It is also difficult to study how the brain regulates behaviour in response to environmental changes like food availability in larger animals with more complex nervous systems. Instead, scientists often study less complex animals like a type of worm called C. elegans, because this model organism has a simpler nervous system and it is easier to observe its feeding behaviours. Previous observations have revealed that well-fed worms travel backwards when they are hungry, revisiting sites where they have previously found food. Yet, when the worms are starving, they move forward more frequently, presumably to find new sources of food. Now, Ahmadi and Roy show starving worms activate an enzyme called AMP-activated protein kinase (or AMPK for short). Worms genetically engineered to lack this enzyme tend to move backward when they are starved, instead of moving forward like typical starving worms. This shows that AMPK triggers a wider search for new food sources. Further experiments showed that AMPK acts to inhibit two receptors, which in turn, affects the activity of two different neurons. These two neurons work together to change the animal’s behaviour and boost the likelihood the animal will be able to find a new food source when food is scarce. More complex animals, including humans, also have the receptors and brain cells targeted by AMPK in response to starvation. Future studies are needed to determine whether a similar chain of events occurs in creatures with more complicated nervous systems.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.002 |
| Research integrity | 0.003 | 0.002 |
| Insufficient payload (model declined to judge) | 0.084 | 0.033 |
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".