Summary: Researchers report they may have discovered neurons that are connected to a tendency to indulge in binge behaviors, at least in rats.
Source: Johns Hopkins University.
Rats that responded to cues for sugar with the speed and excitement of binge-eaters were less motivated for the treat when certain neurons were suppressed, researchers discovered.
The findings suggest these neurons, in a largely unstudied region of the brain, are deeply connected to the tendency to overindulge in response to external triggers, a problem faced by people addicted to food, alcohol and drugs. The findings, due to appear in the June 15 issue of the journal Neuron, are now available online.
“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 Jocelyn M. Richard, a Johns Hopkins University post-doctoral fellow in psychological and brain sciences and the report’s lead author. “Our findings show where in the brain this connection between environmental stimuli and the seeking of food or drugs is occurring.”
First researchers trained rats to realize that if they heard a certain sound, either a siren or staccato beeps, and a pushed a lever, they would get a drink of sugar water. Then, as the rats performed the task, researchers monitored neurons within the ventral pallidum area of the rats’ brains, a subcortical structure near the base of the brain.
When the rats heard the cue linked to their treat, a much larger-than-expected number of neurons reacted — and vigorously, researchers found. They also found that when the neuron response was particularly robust, the rats were extra quick to go for the sugar. The researchers were able to predict how fast the rats would move for the sugar just by observing how excited the 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.
Next, the researchers used “optogenetics,” a technique that allows the manipulation of cells through targeted beams of light, to temporarily suppress the activity of ventral pallidum neurons while the rats heard the sugar cues. With those neurons inactive, the rats were less likely to pull the sugar lever; when they did pull it, they were much slower to do so.
That ability to slow and calm the reaction to cues or triggers for binges could be key for people trying to moderate addictive behaviors, Richard said.
“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.
About this autism research article
In addition to Richard, the research team included Frederic Ambroggi, a researcher at Aix-Marseille Université and Le Centre National de la Recherche Scientifique; Patricia H. Janak, a Bloomberg Distinguished Professor in the Department of Psychological and Brain Sciences and the Solomon H. Snyder Department of Neuroscience at Johns Hopkins; and Howard L. Fields, director of the Wheeler Center for the Neurobiology of Addiction at the University of California, San Francisco.
Funding: The research was supported by National Institutes of Health grants AA022290 and AA014925 and by the State of California.
Source: Jill Rosen – Johns Hopkins University Image Source: This NeuroscienceNews.com image is credited to Jocelyn Richard/JHU. Original Research:Abstract for “Ventral Pallidum Neurons Encode Incentive Value and Promote Cue-Elicited Instrumental Actions” by Jocelyn M. Richard, Frederic Ambroggi, Patricia H. Janak, and Howard L. Fields in Neuron. Published online May 26 2016 doi:10.1016/j.neuron.2016.04.037
Cite This NeuroscienceNews.com Article
[cbtabs][cbtab title=”MLA”]Johns Hopkins University. “Researchers Find What Could Be Brain’s Trigger for Binge Behavior: Rat Study.” NeuroscienceNews. NeuroscienceNews, 1 June 2016. <https://neurosciencenews.com/neuroscience-binge-behavior-4354/>.[/cbtab][cbtab title=”APA”]Johns Hopkins University. (2016, June 1). Researchers Find What Could Be Brain’s Trigger for Binge Behavior: Rat Study. NeuroscienceNews. Retrieved June 1, 2016 from https://neurosciencenews.com/neuroscience-binge-behavior-4354/[/cbtab][cbtab title=”Chicago”]Johns Hopkins University. “Researchers Find What Could Be Brain’s Trigger for Binge Behavior: Rat Study.” https://neurosciencenews.com/neuroscience-binge-behavior-4354/ (accessed June 1, 2016).[/cbtab][/cbtabs]
Ventral Pallidum Neurons Encode Incentive Value and Promote Cue-Elicited Instrumental Actions
Highlights •Cue responses in ventral pallidum precede “upstream” responses in nucleus accumbens •Ventral pallidal neurons selectively respond to a cue predicting reward availability •Cue responses are predictive of both the likelihood and latency of reward seeking •Ventral pallidal photoinhibition reduces reward-seeking likelihood and vigor
Summary The ventral pallidum (VP) is posited to contribute to reward seeking by conveying upstream signals from the nucleus accumbens (NAc). Yet, very little is known about how VP neuron responses contribute to behavioral responses to incentive cues. Here, we recorded activity of VP neurons in a cue-driven reward-seeking task previously shown to require neural activity in the NAc. We find that VP neurons encode both learned cue value and subsequent reward seeking and that activity in VP neurons is required for robust cue-elicited reward seeking. Surprisingly, the onset of VP neuron responses occurs at a shorter latency than cue-elicited responses in NAc neurons. This suggests that this VP encoding is not a passive response to signals generated in the NAc and that VP neurons integrate sensory and motivation-related information received directly from other mesocorticolimbic inputs.
“Ventral Pallidum Neurons Encode Incentive Value and Promote Cue-Elicited Instrumental Actions” by Jocelyn M. Richard, Frederic Ambroggi, Patricia H. Janak, and Howard L. Fields in Neuron. Published online May 26 2016 doi:10.1016/j.neuron.2016.04.037