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It feels like every time I turn on my TV, I see a commercial about yet another betting app! Not only that, but I am constantly hearing people around me talking about how they're always losing money gambling but they can't stop. I am extremely curious to see why this is the case, and what effects gambling has on the brain.

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In pursuit of understanding more about gambling and its respective effects, I decided to explore the literature and learn about the impact that pathological gambling has on the brain. Specifically, I explored studies that researched gambling in animal models. I found three studies that provided some key information regarding the effects and the translational science behind the research!

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The first article I found was a study completed by Cocker and Winstanley (2015). The purpose of this study was to discuss the applicability and effectiveness of particular rodent behavioural paradigms in stimulating the decision-making processes that are related to pathological gambling. Looking into this article will help me grasp how these paradigms can expand the understanding on how pathological gambling develops.

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The University of Toronto Libraries system is the largest academic library in Canada and consists of 44 libraries located on three university campuses: St. George, Mississauga and Scarborough.

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This research was very innovative! The authors used three different tasks to study decision-making in rodents. I will discuss the first two tasks - the Rodent Slot Machine Task (rSMT) and the Rodent Betting Task (RBT)

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Don't let the photo scare you, the task is simple! The rats responded to a series of three flashing lights, similar to a slot machine that is at the casino. The response from the rats caused the lights on the machine to turn on or off. If the rats 'won', all three lights would turn on, and any other light pattern would correspond with a 'loss'. Look at the photo above, figure F shows this!

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After each roll or trail, rats had to choose between two levers (left-roll, or right-collect). If the rats chose the roll lever, a new trial would start. However, choosing the collect lever would result in 10 sugar pellets on a win but ended up in a 10-second time out on a loss. This is how researchers would mimic the aspect of gambling to the mice - fascinating!

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The rats ended up distinguishing win trials from most loss trials - absolutely crazy! They chose the collect lever 100% of the time on win trials but only about 15-35% during loss trials with 1 or no lights. This suggests the rats did not associate these trials with the opportunity to win a reward. To add to this, rats selected the collect lever in trials with 2 lights, suggesting they predicted rewards in these trials.

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The behavioural patterns shown in the research done by Cocker and Winstanley (2015) resemble the near-miss effect that is seen in humans. An example of the near-miss effect is prominent in individuals playing slot machines, making participants believe they're "getting used to the game".

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The dopamine system is thought to be a key contributor to the near-miss effect. Researchers looked into this and tested how dopamine agents affect the performance of the task. The effect of this was extremely prominent - rats receiving the highest dose responded to over 70% of loss trials as if they were wins. These results could suggest that one or two more D2 family play a distinct role in modulating reward expectancy.

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Think of a time when you have placed a friendly bet with a friend, it may have ended in the losing person risking "double or nothing" for the reward. This analogy represents the second task used in the study. The rodent betting task was designed to try and analyze how much change in bet size is required to assess risk tolerance (Cocker & Winstanley, 2015).

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The photo above explains the schematic layout of the task. In brief, the rats chose between responding to a safe lever, guaranteeing a specific reward, or an uncertain lever that delivers double or nothing of the reward. I found it truly fascinating that researchers can train the rats to understand and participate in this task!

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The behaviour of wager-sensitive rats in this task resembles the notion of risk-aversion in humans - where willingness to gamble decreases as the reward size gets larger. You can probably think of a time this has happened in your life, I know I can!

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The current research indicates that decreased striatal D2 receptor density may not be a key contribution of pathological gambling, despite the similarities to other addiction disorders (Cocker & Winstanley, 2015). These results suggest that although they may have a minor impact on pathological gambling, individuals with baseline levels of risk aversion or wager sensitivity may not be a direct factor in determining the possibility of adopting pathological gambling. Researchers Cocker and Winstanley (2015) describe this bias as delay-discounting, which requires further research.

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This research has aimed to factor out various aspects of dysfunctional decision-making under uncertainty. In doing this, Cocker and Winstanley (2015) have proved that animal models are in fact a useful tool in researching the role decision-making has in those who engage in pathological gambling. This work was extremely cool to read up on, providing clarity on how decision-making processes affect gambling.

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This study allowed research to model reward sensitivity and expectancy, comparing the results of both tasks to human models. Using translational tasks like the rodent slot machine and rodent betting task, the researchers could study how animals respond to loss and near-miss occurrences, checking brain activity for similarities in humans with pathological gambling.

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Although this study provided insight into the nature of pathological gambling, there are some limitations to the study. Firstly, losses are represented in animal models as a caloric deficit. In reality, humans experience much greater loss, typically involving money. This comparison of loss may not correlate with the realities of pathological gamblers.

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That's not all! Unfortunately, none of the tasks performed model the problematic engagement with gambling. Remember dopamine? These models drastically increase dopamine levels from the administration of drugs, potentially skewing the results.

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PODCAST

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I continued diving into my search after reading this article and found super interesting research by Rivalan et al. (2009). Think of a scenario where humans try to refrain from instant gratification to select an option with the best long-term payoff. The complex and conflicting choices humans face can be tested in the 'Iowa Gambling Task'. These researchers noticed the gap in investigating poor decision-making in animal models. Therefore, Rivalan et al. (2009) designed a single-session rat gambling task that is similar to the Iowa gambling task, allowing for a direct comparison between good and poor decision-making.

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The University of Toronto Libraries system is the largest academic library in Canada and consists of 44 libraries located on three university campuses: St. George, Mississauga and Scarborough.

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The photo above represents a comparison of the Iowa gambling (Figure A) and the new rat gambling task (Figure B). In the task used in this study, 12 identical chambers containing four circular holes (A-D) were utilized. Researchers Rivalan et al. (2009) tested the rats in multiple different conditions.

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The first condition the researchers discussed was the control of sensitivity to different penalties. Simply put, a group of 9 rats were able to freely choose between the four holes - each choice resulting in a different outcome. Any choice a rat made would result in one pellet immediately being given to them, but choosing A or B could potentially be followed by longer and unpredictable penalties for the rats. The penalties are similar to those in the previous study - a timeout would be the 'punishment'.

The conditions of the second group are similar to those above, but choosing A or B would now result in the immediate delivery of two pellets to the rats.

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Researchers found that when choices were equally rewarded, rats could determine different timeouts in a single session. How cool is that!! Ritavan et al. (2009) stated that no biases or preferences were displayed as animals made equal choices from available options. To add to this, all rats quickly developed a preference for the shorter timeouts, then continued to favour the options that were not penalized. These results show the rats carry the cognitive processes that are needed for decision-making and understand how to weigh the risks. Absolutely amazing!

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From the rat gambling task, results revealed three distinct categories:

1) A majority of good decision-makers, all having a strong preference for the advantageous options (58%)

2) Poor decision-makers with a preference for the lesser options (25%)\

3) Those showing no preference (17%)

Interestingly, increasing the difficulty of the task showed no difference in the proportions of the good and bad decision-makers

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Researchers developed a task that is specific to rats, modeling a task that is used in humans! If you ask me, I'd say that is pretty revolutionary. The rat gambling task can be utilized by future researchers, attempting to build off of these results or trying to find different conclusions

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The study is great! It is just super new. Due to the newness of the task, the test-retest reliability may be impaired as no other studies have used this method. Follow-up studies can be conducted in order to improve the validity and tweak errors that have possibly been made in this current research.

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The last article I found was super intriguing. The research was completed by Di Ciano and Le Foll (2016). These authors had evidence to believe that the opioid naltrexone may be helpful in treating pathological gambling. The purpose of this task was to determine and evaluate the effects this opioid has in an animal model of gambling - specifically using the rat gambling task.

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The University of Toronto Libraries system is the largest academic library in Canada and consists of 44 libraries located on three university campuses: St. George, Mississauga and Scarborough.

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I know...it sounds crazy! 24 male rats took part in the rat gambling task in this study. The researchers administered naltrexone to these rats 30 minutes prior to the test session on the day of testing. In this task, animals are analyzed for their judgment about the likelihood and duration of a time-out punishment, as well as which response option carries the largest reward.

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Yup! Another author using this task - researchers seem to love it. Researchers Di Ciano and Le Foll (2016) thoroughly trained the rats to understand the task at hand. There were four different response holes in the chambers, which were each associated with different amounts of rewards or punishments. The rats initiated each trial by poking their nose at a food tray, beginning a 5-second interval before the stimulus is turned on in all four holes.

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Rats must figure out the best way to get as many reinforcements per session as they can. To accomplish this, rats must suppress the option that yields the biggest reward because it also results in the most punishment; options with smaller rewards yield more pellets each session. In the task, there are four choices (P1, P2, P3, and P4), and they all produce 1-4 pellets. P2 and P1 are 'advantageous' and optimal strategies whereas P3 and P4 are the opposite. Rats who made more advantageous choices were classified as an optimal group (15 rats) and the other 9 nine rats were classified as suboptimal, as they made more disadvantageous choices.

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The photo above describes all possible choices and outcome possibilities the rats had in front of them.

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When the rats poke their nose in one of the four holes, the lights will all turn off and either delivers a reward or starts a timeout "punishment. There are four possible outcomes Di Ciano and Le Foll (2016) discussed:

1) reward - food is given to the rat

2) punishment - timeout. similar to those discussed in previous studies.

3) omission - if the rats fail to make a response

4) premature responses - punished by a 5-second timeout.

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Researchers conducted a three-way ANOVA to see if there was any significance between the three variables; dose, group, and choice. The initial ANOVA revealed significance. Going even further, researchers conducted a simple effect ANOVA between the dose and group conditions and also found significance (Di Ciano & Le Foll, 2016)

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Oops! Almost forgot. The researchers found that naltrexone improved the rats' performance on the task in a subset of rats that chose the 'tempting' disadvantageous choice and that naltrexone increased response for P1 in the Suboptimal group of rats (Di Ciano & Le Foll, 2016). To simplify, the present study showed that naltrexone improved choice behavior in a subset of rats that made fewer advantageous choices at baseline. Its not much, but it's something!

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The figure above demonstrates the amount of naltrexone given and the percentage of the rats' advantageous choices. It is clear to see the difference from the optimal and suboptimal groups of rats!

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Studying the effects of opioids in treating pathological gambling is new to the field. This study provides future researchers with a baseline of the dos and don'ts of utilizing naltrexone as a method to help the effects of gambling.

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Not everything is perfect! Although the results from this research can pertain to those who experience pathological gambling, they cannot be related to those who participate in healthy gambling. therefore, the results are not generalizable to all - hurting the external validity.

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The translational science within this study centers on using animal models to better understand the cognitive mechanisms that signify pathological gambling in humans and potential remedies that can utilized to minimize the effects (Cocker & Winstanley, 2015). The use of animal models has enabled the researchers to be able to replicate key aspects of pathological gambling, with the intent to pinpoint specific neurological processes that are involved in these behaviours. By utilizing these tasks, researchers were able to create a controlled environment to mimic the human cognitive errors that are often seen in pathological gamblers, such as risk and loss aversion and the near-miss effect. In addition, the tasks completed in this study were practiced in a way to reflect the types of activities that pathological gamblers engage in, such as a slot machine. These innovations in the experimental design of this study has revolutionized the way research in completed in this field, providing the ability to replicate specific behaviours and neurological processes.

The rat slot machine task and the rat betting task allowed Cocker and Winstanley (2015) to recognize the role dopamine has on the brain of a pathological gambler. Similar to this, a study done by Choi et al. (2012) found dopamine to be apparent in the ventromedial caudate nucleus when human participants were anticipating gain or loss. Comparing these two findings is important as it suggests that the cognitive mechanisms that are observed in the animal models are also relevant in humans, making the results more generalizable to human pathological gambling.

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Rivalan et al. (2009) have contributed to the field by creating an animal model gambling task that directly correlates to the Iowa gambling task that is used in human research. Creating this task has opened the door for future researchers who are interested in this field, providing a baseline study that they can look back on to understand what works and doesn’t work for the model. This is a critical aspect in advancing the scientific understanding of certain notions, as it allows researchers to close to gap between studies conducted in animals or labs and clinical applications.

Clark et al. (2013) discuss the importance of attempting to model gambling decisions that are coherent to the choices that are frequent in human neuropsychology and cognitive psychology. This article emphasizes the use of the Iowa gambling task, praising its ability to detect the cognitive functions and processes that are involved in pathological gambling. Additionally, research done by Ouerchefani et al. (2019) highlights the benefits of using the Iowa gambling task, highlighting the implications that can be made from the results of this task. This recognition from other scholars provides Rivalan et al. (2009) with a strong theoretical framework that supports the validity of their task, adding credibility to the experimental design and its potential in the field of neuroscience.

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Examining the effects of drugs for treating disorders focuses on the process of moving on from basic scientific research and continuing to clinical applications, where researchers can get a more in-depth understanding of the neurological and cognitive mechanisms behind treating gambling. The testing of opioids as a possible remedy for pathological gambling is an ongoing notion in the field of neuroscience. Di Ciano and Le Foll (2016) have taken this approach and executed it in a way that studies its effects on animal models. The experimental design used in this study can be referenced by future researchers, where they can replicate the methods and translate them to human research. Practicing this method on animals can help researchers understand the proper dosage of naltrexone, safety measures, and behavioural responses, which are all vital to acknowledge before taking this method to humans.

Naltrexone can block opioid receptors, which are heavily involved in the brain's reward system, and reinforce gratifying behaviours, providing a rationale behind using this drug as a method (Grant et al., 2003). With the primary mechanism of antagonizing these receptors, naltrexone has been tested in psychological disorders and addictive behaviours where a consistent symptom that diagnosed individuals face is urges (Toneatto et al., 2010). These disorders include borderline personality disorder, bulimia nervosa or obesity, as well as alcoholism or nicotine addiction. There have been mixed results regarding the efficacy of naltrexone in treating these disorders, sparking interest in the field to obtain significant results (Grant et al., 2003). This current study done by Di Ciano and Le Foll (2016) has taken this well-rounded information regarding Naltrexone and utilized it to their benefit, creating research that could offer a new avenue for treating pathological gambling.

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Gambling has become very normalized and prevalent in today’s society, specifically in the realm of sports entertainment. Being a big sports fan, as well as being surrounded by the sports environment, it is evident that the addiction to gambling affects those around me. This normalization of gambling is what brought me towards researching this topic, curious to see the effects it truly has on people’s brains. Prior to this research, I was aware that gambling disrupts decision-making and that it is harmful. However, I was not aware of the specific effects it had on the brain and cognitive processes.

From this research, I learned how the cognitive deficits that are seen in humans with pathological gambling are also seen in rats in the lab. Researching the effects of gambling has taught me that there have been studies that have tested the benefits of using opioids to alleviate pathological gambling deficits. From the perspective of neuroscience, this research impacted the way that I understand the human brain. As a human being, doing this research has made me want to encourage others to stop gambling, as the effects of it are detrimental, hurting decision-making and cognitive processes.

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2009 Marion Rivalan - Risk Prone Individuals Prefer the Wrong Options on [retrieved_2025-03-24]

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2015 P J Cocker - Irrational beliefs biases and gambling Exploring t [retrieved_2025-03-24]