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Final paper proposal and sources

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For my final paper, I am interested in researching addiction behavior and specifically how well the paradigm of sign-tracking versus goal-tracking behavior models addiction. Of course, addiction is an extremely complex and multifaceted disorder to study and understand. With this in mind, I am aiming to isolate this specific behavior paradigm and evaluate 1) differences in how it is performed in animals, 2) the similarities or dissimilarities between conclusions across various studies as to what the paradigm represents and 3) its construct validity in modeling and/or predicting addiction behavior between animals and humans. 

The task in [1] involved a lever being pressed for food delivery. Sign-trackers primarily approached and contacted the lever (the input) while goal-trackers preferentially approached the site of food delivery (the output). When later trained on a choice task between receiving food or an infusion of cocaine, sign-trackers chose cocaine over food significantly more often. Their research question asked whether the tendency to sign-track to a food cue was predictive of rats’ choice of cocaine over food. 

A primary conclusion of [2] was that sign-tracking and goal-tracking behavior may be due to different structures and pathways in the brain which can lead to differences in the manifestation of addiction behavior. This study used a reward devaluation procedure (i.e. the reward was paired with illness in the absence of the conditioned stimulus) and examined whether sign- and goal-tracking behavior increased or decreased. 

[3] is a review article that covers a wide range of material that could be useful for finding other sources in the coming weeks. It also focuses on how sign-tracking influences gambling addiction, which was the original disorder that interested me in wanting to research this topic. One main conclusion the review suggests is that sign-tracking animals are especially vulnerable to addiction due to the attribution of incentive salience to drug cues. 

[4] is another review article that I find very relevant for how it bridges this research between animal models and human behavior. Along with the previous source, it is an extremely new paper and could be interesting to compare to older studies. Overall, the article looks at attributes of sign- and goal-tracking animal profiles with an emphasis on neurobiological and behavioral profiles that have the greatest relevance to human behaviors. 

[5] builds upon the concepts of source [2] in saying that sign-tracking and goal-tracking are governed by distinct neurochemical mechanisms. Their hypothesis was whether the use of distinct conditioned stimuli could have different neurochemical responses (i.e. recruit different dopamine receptor subtypes) that lead mice to develop one behavior type over the other. They show that the selective involvement of D2 activity in sign-tracking may reflect its importance in motivational processes while D1 is involved in both sign- and goal-tracking, reflecting its general role in learning associations. 

[1] Tunstall, B., & Kearns, D. (2015). Sign-tracking predicts increased choice of cocaine over food in rats. Behavioural Brain Research, 281(5), 222-228. https://doi.org/10.1016/j.bbr.2014.12.034

[2] Morrison, S., Bamkole, M., & Nicola, S. (2015). Sign Tracking, but Not Goal Tracking, is Resistant to Outcome Devaluation. Frontiers in Neuroscience, 9, 468. https://doi.org/10.3389/fnins.2015.00468

[3] Anselme, P., & Robinson, M. (2020). From sign-tracking to attentional bias: Implications for gambling and substance use disorders. Progress in Neuropsychopharmacology & Biological Psychiatry, 99, 109861. https://doi.org/10.1016/j.pnpbp.2020.109861

[4] Colaizzi, J., Flagel, S., Joyner, M., Gearhardt, A., Stewart, J., & Paulus, M. (2020). Mapping sign-tracking and goal-tracking onto human behaviors. Neuroscience and Biobehavioral Reviews, 111, 84-94. https://doi.org/10.1016/j.neubiorev.2020.01.018

[5] Roughley, S., & Killcross, S. (2019). Differential involvement of dopamine receptor subtypes in the acquisition of Pavlovian sign-tracking and goal-tracking responses. Psychopharmacology, 236(6), 1853-1862. https://doi.org/10.1007/s00213-019-5169-8

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