This Is Your Brain Binging on Food, Sex, Alcohol, or Drugs
Neuroscientists have pinpointed a brain region that triggers binge behavior.
Posted May 31, 2016
We all know the feeling of being compelled to overindulge. Depending on your vice, binging can lead to: overeating, blackout drinking, drug overdoses, sexual compulsive behaviors, etc. The brain mechanisms involved in binge behaviors are complex and enigmatic.
However, a new study published online today has identified a cluster of neurons in a subcortical brain region called the Ventral Pallidum (VP) that appears to trigger binges. These neurons selectively respond to a cue that predicts reward availability. They appear to be deeply connected to the tendency to binge in response to external triggers.
The June 2016 paper, “Ventral Pallidum Neurons Encode Incentive Value and Promote Cue-Elicited Instrumental Actions,” is available online and will appear in the journal Neuron.
Neurons in the Ventral Pallidum Are Linked to Binging Behaviors
In the new study from Johns Hopkins University, the researchers found that rats could be conditioned to engage in binge behaviors if external cues were linked to receiving a sugary treat. In fact, when certain neurons in the VP were activated, the rats binged on sugary treats with the same voracity that has been observed in human binge eaters.
However, when the ventral pallidum neurons were suppressed the rats became much less motivated to seek out the sugary treat. Although this was an animal study, the findings could have implications for any type of binging behaviors.
Inhibiting the ventral pallidum appears to reduce reward-seeking behaviors and the likelihood of a binge. Conversely, it appears that cued responses that activate VP neurons increase the likelihood of a lab rat having a reward-seeking binge.
In a statement, Jocelyn M. Richard, a Johns Hopkins University post-doctoral fellow in psychological and brain sciences, and lead author of this study said,
"External cues—anything from a glimpse of powder that looks like cocaine or the jingle of an ice cream truck—can trigger a relapse or binge eating. Our findings show where in the brain this connection between environmental stimuli and the seeking of food or drugs is occurring. We were surprised to see such a high number of neurons showing such a big increase in activity as soon as the sound played"
In the first stage of this study, the researchers trained rats to realize that if they heard a certain sound (a siren or staccato beeps) and then pushed a lever that they would receive a drink of sugar water. This is classical conditioning in action. As the rats performed the task repeatedly, the researchers were monitoring neurons within the ventral pallidum area of the rats' brains.
The researchers observed that when the rats heard the cue linked to their sugary treat, a much larger-than-expected number of neurons in the VP reacted. This response led to robust, binge like behaviors.
The researchers also observed that when the neuron response was especially robust, the rats were extra quick to gobble up tons of sugar. In fact, the researchers were able to predict how fast the rats would move for the sugar just by observing how excited the VP neurons became at the sound of a cue.
Lastly, the researchers used optogenetics—a new technique which allows researchers to manipulate cells using targeted beams of light—to temporarily suppress the activity of ventral pallidum neurons while the rats were hearing the sugar cues. Interestingly, when the VP neurons were deactivated, the rats were less likely to pull the sugar lever. And, if they did finally pull the lever, they were much slower to do so. This is a fascinating discovery that helps to explain the neurobioligical underpinnings of binging.
Classical Conditioning and Pavlovian Responses Can Trigger Binging Behaviors
This week, another study related to binging behaviors was published by researchers from Concordia University in Canada. The Canadian researchers found that when they paired a visual cue with receiving alcohol that rats came to expect alcohol every time they saw that cue. In my opinion, this study dovetails perfectly with the findings from Johns Hopkins on binge behaviors published today.
The May 2016 Concordia study, “The Attribution of Incentive Salience to Pavlovian Alcohol Cues: a Shift from Goal-Tracking to Sign-Tracking,” was published in the journal Frontiers in Behavioral Neuroscience.
For this study, a team of Concordia students worked with 25 lab rats who were conditioned to associate a specific cue with the presence of ethanol, which is the predominant alcohol found in the alcoholic beverages that humans consume.
As we know from life experience and empirical research, in many ways, humans aren’t much different than other animals.The researchers emphasize that we can use animal models to figure out ways to minimize unwanted binging behaviors—such as responding to cues that lead to alcohol abuse in humans, too.
Just like Pavlov's dogs, humans often become conditioned to associate environmental cues with rewards. This is a typical Pavlovian response. Obviously, the type of Pavlovian cues that lead someone to crave alcohol can lead to binge drinking and addiction.
In a statement, Nadia Chaudhri, the study's lead author and professor in the Department of Psychology, said,
"Alcohol addiction is compounded by our ability to learn about predictive cues. Conditioned reactions to those cues can trigger behaviours that result in drinking, like turning into the SAQ or reaching for a beer.
These preferences could be driven by the sensory properties of alcohol, like its taste, smell and how it looks. It is important for people to realize that drinking alcohol is a complex behavior, and in addition to what alcohol does to our brains, it also plays a role in regulating our behaviours."
Eventually, when the cue was presented, rats approached the location where alcohol was about to be delivered. But after a time, they stopped performing this behavior and instead began approaching and interacting with the cue. According to the researchers, "drinkers wishing to make a change in their habits shouldn't just focus on the booze itself, but on all the factors that surround alcohol consumption."
Conclusion: Minimizing Triggers May Subdue VP Neurons and Prevent Binges
In a previous Psychology Today blog post, “What Triggers Cravings?” I discussed how person-specific cues can also trigger cravings that lead to binges. If you are struggling with any type of addiction, the latest empirical research suggests, it’s important to surround yourself with people, places, and things that keep your ventral pallidum calm.
For me personally, visualizing the red and pink triangles in the image at the top of this page as on “on-off” switch that can either trigger a binge—or prevent binging behaviors—is a helpful visualization. I hope this information helps you, too, if you are prone to any type of binging behaviors.
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