Bibliographic record
Abstract
The incidence of obesity has nearly doubled in the last 30 years, and this rise in incidence is directly linked to increased consumption of energy-dense foods.In addition, the majority of people attempting to lose weight report relapse to high fat foods while dieting.Recent studies suggest that the orexigenic hormone ghrelin can bind to dopaminergic cells in the ventral tegmental area (VTA), a key structure in the brain's reward system, and increase the incentive value of such foods.Specifically, studies have shown that ghrelin increases the motivation to work for food rewards, enhances the preference for contexts associated with food rewards, and augments the locomotor and physiological responses associated with food rewards.The experiments described in the present thesis aimed to establish the role of ghrelin in 2 additional reward-based feeding behaviours thought to contribute to the current obesity epidemic.The first behaviour is the consumption of palatable desserts after meals that adequately satisfy an individual's energetic demands.The second behaviour is the tendency to relapse to food seeking after a period of abstinence.In order to accomplish this, we compared ghrelin receptor knock out (KO) rats to rats possessing an identical genetic background, with an intact ghrelin receptor gene (wildtype rats -WT) in tasks designed to model these behaviours.In addition, we examined outbred rats receiving chronic infusions of either ghrelin or a ghrelin receptor antagonist in the VTA.Overall, the data presented in this thesis confirmed the role of ghrelin signalling in dessert consumption; KO rats ate less cookie dough when sated than WT rats.KO and WT rats performed similarly in operant conditioning and conditioned place preference models of relapse, also known as the operant and CPP reinstatement tests.In contrast, pharmacological action at the ghrelin !iii! receptor in outbred rats could enhance and attenuate the expression of reinstatement of food seeking that is induced by food reward cues following administration of ghrelin and a ghrelin receptor antagonist, respectively.It is therefore likely that ghrelin is involved in the tendency to relapse to unhealthy eating habits in dieting individuals, and that this effect is due, in part, to its action in the reward system, particularly within the VTA.!iv! help in the lab and for making every day fun.Much gratitude and love to my parents for their encouragements and insights.Finally, I would like to thank Warren, who is the best partner I could have ever hoped for, and whose support and love mean the world to me.And Corrie, who was there for every part of my grad school experience, and whose friendship I will continue to treasure for years.!v! Dedication !Je dédie cette thèse à mes grands-parents.Mimi et Grand-Père ont toujours eu l'éducation très à cœur et se sont toujours intéressés à mon parcours académique.Ils ont transmis leur amour de l'école à ma mère, qui, avec mon père, a développé ma curiosité scientifique dès mes tous premiers projets d'expo-science.Ils sont une source d'inspiration et de support inébranlable.!vi! !vii! Chapter 5: The role of ghrelin in reinstatement -conditioned place preference!.....!82! Hypothesis 2: ghrelin facilitates the reinstatement of palatable food seeking that is triggered by food priming and food associated 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 | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".