Gambling is a complex behavior influenced by multiple factors in the brain.
New research in mice provides insight into the neurobiology underlying key aspects of gambling such as making the initial decision to gamble and persistently chasing losses.
Key Facts:
- Mice exhibit typical gambling behaviors like choosing to gamble more when odds of winning are higher and chasing losses trying to win back money.
- Blocking serotonin 2C receptors reduced mice’s initial decision to gamble but didn’t affect loss chasing behavior.
- Activating serotonin 1A receptors increased loss chasing but not initial gambling.
- The drug modafinil decreased both initial gambling and loss chasing behaviors.
The Psychology of Gambling
Gambling involves weighing risks and rewards.
Most people gamble recreationally in a controlled manner. But for some, harmful patterns emerge like loss of control and chasing losses.
This loss chasing, continuing to gamble to recover mounting losses, is a key feature of problematic gambling. It can lead to severe financial, personal, and social consequences.
What drives loss chasing? Theories suggest it may result from how people value losses.
As monetary losses build up during a session of gambling, the decreasing marginal impact on perceived value of continuing to lose money promotes further risk taking.
Or it may be driven by reinforcement of persistently rewarded behaviors.
Regardless of the psychological basis, loss chasing is clearly a critical mechanism by which gambling becomes harmful.
Scientists have tried to break down different aspects of gambling in humans, like deciding to chase losses or quit.
Evidence points to separate neural systems and neurotransmitters involved in these choices.
However, animal studies directly comparing mechanisms behind starting to gamble versus persisting haven’t been done previously.
Neurotransmitters: Serotonin and Dopamine
The neurotransmitters serotonin and dopamine are prime suspects in gambling behaviors.
Drugs that mimic serotonin have shown promise treating problem gambling.
Dopamine drives reward and motivation pathways.
Imaging research finds gambling alter dopamine levels.
Serotonin and dopamine also interact in complex ways still being untangled.
Animal studies demonstrate serotonin and dopamine impacts on gambling-like behavior.
In rats, activating serotonin 1A receptors or blocking dopamine D2 receptors reduced simulated loss chasing.
Rats also chased losses less when serotonin activity was increased or dopamine decreased in a brain region called the striatum.
But it wasn’t clear if serotonin and dopamine selectively affect initiating gambling versus sustaining it.
Testing Gambling Behavior in Mice
Trevor Humby and colleagues developed a mouse model to investigate the neurobiology of gambling initiation versus persistence.
They trained mice to touch screens to receive food rewards. In “choice” trials, mice chose between a “gambling” option or “quitting.”
Gambling produced big rewards for wins but punishments of reward delays for losses.
Quitting induced milder delays letting mice advance faster.
In “loss chase” trials after a lost gamble, mice chose to keep gambling or quit.
The odds of winning, losing, and length of loss chasing sequences were systematically varied.
The researchers could thus examine what affected opting to gamble in the first place versus persistently chasing losses.
They also gave drugs altering serotonin and dopamine to probe their distinct roles.
Mice Reliably Demonstrated Gambling Behaviors
Like humans, the mice gambled more when winning odds were higher.
They also chased losses longer under better odds.
Altering the odds of winning successfully tuned mice’s motivation to take risks.
This validated mice as a model for facets of gambling seen in humans.
The researchers could now manipulate serotonin and dopamine systems to uncover impacts on initiating versus sustaining gambling.
Serotonin Influences Initial and Persistent Gambling Differently
The team tried drugs activating the serotonin 1A and 2C receptor subtypes (5-HT1A & 5-HT2C).
Blocking 2C receptors reduced the initial choice to gamble.
However, it didn’t affect continuing to chase losses once gambling began.
Conversely, stimulating 1A receptors increased loss chasing persistence.
But it left the initial decision to gamble unchanged.
This double dissociation provides intriguing clues to serotonin’s role.
2C receptors are found in brain regions like the prefrontal cortex involved in decision making and self-control.
Deactivating them may make mice more cautious or risk averse.
1A receptors occur in areas like the striatum which drives reward-seeking and habits.
Activating them may energize mice’s motivation to persevere despite punishments.
But this wouldn’t necessarily make them start gambling sooner.
The findings align with human studies suggesting separate effects of serotonin drugs on choosing to chase versus quitting.
Serotonin may mediate distinct facets of gambling through localized receptors regulating decision making, motivation, and compulsivity.
The Smart Drug Modafinil Reduces Gambling Behaviors
Modafinil is a stimulant used to treat narcolepsy and shift work sleep disorder.
Evidence indicates it may improve cognition in healthy people and those with psychiatric disorders.
There’s interest in using modafinil to treat addictions including problem gambling.
In this study, a moderate dose of modafinil decreased both mice’s initial choice to gamble and persistent loss chasing. It didn’t impair their motivation or ability to perform the task.
This shows modafinil’s potential to reduce gambling behaviors without sedation or generalized effects.
How does modafinil work in the brain? Rather than acting like amphetamines, it seems to indirectly enhance dopamine and norepinephrine.
It affects multiple other neurotransmitters too. Through diffusely bolstering attention and arousal, it may strengthen self-control over urges to chase excitement from gambling.
Future Directions in gambling research
By developing a mouse model, researchers can now leverage genetic tools to elucidate gambling’s biological underpinnings.
Gene editing techniques will help pinpoint relevant receptors and circuits.
Mice enable large pharmacological screens to discover novel treatment targets.
Studies should examine neural activity dynamics in gambling decisions using implanted electrodes or imaging.
Are distinct patterns and brain regions involved in initiating gambling versus sustaining it?
How do serotonin, dopamine and other neuromodulators sculpt these dynamics?
A limitation is the simplified nature of rodent gambling tasks versus complex human gambling.
Some behavioral and motivational elements may not translate across species.
Integrating human neuroimaging and genetics will be important to validate and extend animal findings.
Uncovering the intricacies of gambling neurocircuitry could ultimately help those plagued by gambling disorder.
It may suggest more individualized treatment approaches based on specific dysfunctional mechanisms.
Refining therapies requires a deeper comprehension of this prevalent but enigmatic disorder rooted in our brain’s machinery for value, motivation and control.
References
- Study: Effects of 5-ht2c, 5-ht1a receptor challenges and modafinil on the initiation and persistence of gambling behaviors
- Authors: Trevor Humby et al. (2020)
