People joke about binging behavior all the time, and laugh about drinking too much at the bar or wolfing down an entire pizza. True binge eating disorder is hardly a laughing matter — the repeated episodes of eating food to the point of discomfort can become life threatening and comes with an increased risk of suicide. As with other forms of addiction, the eating disorder is driven largely by triggers and temptation. Controlling the impulse to binge is central to effective treatment, and researchers from Johns Hopkins University have just made a critical breakthrough in understanding how to do so neurologically.

The team discovered that rats who normally responded to cues for sugar with the speed and enthusiasm of binge eaters were less excited about the treat when researchers suppressed certain neurons. The neurons are in a largely unstudied region of the brain but may be connected to overindulgence in response to an external trigger like food, alcohol, or drugs. People dealing with a binge eating disorder or an addiction deal with an increased tendency to overdo it, an inclination that can have fatal results.

“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,” said Dr. Jocelyn M. Richard, lead author of the study and a Johns Hopkins post-doctoral fellow in psychological and brain sciences, in a press release. “Our findings show where in the brain this connection between environmental stimuli and the seeking of food or drugs is occurring.”

The researchers gave the rats Pavlovian training to recognize a certain sound and associate it with getting a drink of sugar water when they pressed a lever. As the rats performed this task, researchers monitored the neurons within the ventral pallidum region in the rodents’ brains. The area sits near the base of the brain in the basal ganglia and is involved in motivation, behavior, and emotion.

When the rats heard the sound, the researchers observed a much larger number of neurons in the area react than they had been expecting. Also, when there was a particularly strong neuron response, the rats would dart over for the sugar more quickly. Eventually, the team could predict how fast the rats would go for the sugar depending on how excited their neurons became at the sound of the cue.

“We were surprised to see such a high number of neurons showing such a big increase in activity as soon as the sound played,” Richard said.

The researchers then used optogenetics, or targeted beams of light, to manipulate the neurons and temporarily suppress the activity of those in the ventral pallidum. With their neurons inactive, rats who heard the cue were much less likely to pull the sugar lever, and when they did, it was at a much more relaxed pace. Richard said that the technique of slowing down the reaction to triggers for binges could be essential for helping people get their addictive behaviors under control.

“We don’t want to make it so that people don’t want rewards,” Richard said. “We want to tone down the exaggerated motivation for rewards.”

Source: Richard J, Ambroggi F, Janak P, Fields H. Ventral Pallidum Neurons Encode Incentive Value and Promote Cue-Elicited Instrumental Actions. Neuron. 2016.