Can’t stop putting your hand in the candy dish? Scientists may have found why

A national team of scientists has identified a circuit in the brain that appears to be associated with psychiatric disorders including overeating, gambling, drug abuse and even Parkinson’s disease.

“We discovered the brain connections that keep impulsivity in check,” said neuroscientist Scott Kanoski, associate professor of biological sciences at the USC Dornsife College of Letters, Arts and Sciences.

The study was published Oct. 29 in the journal Nature Communications.

Research has indicated that melanin concentrating hormone (MCH) is linked with appetite for food or drugs, but until now scientists hadn’t fully understood how it affects impulse control.

In the current study, the scientists conducted a series of studies on rats that demonstrated that impulsivity is a separate function from hunger and food motivation, and tested lowering and raising the levels of MCH in the rats’ brains.

Based on anatomical brain scans, the scientists were able to identify a neural pathway for impulse control. Neurons in the lateral hypothalamus signal MCH to other neurons in the ventral hippocampus, an area of the brain associated with emotions, memory and inhibitory control.

Kanoski said the next step is for scientists to map the link between the circuit for impulse control and the brain’s rewards system. Such work could eventually lead to the development of better-targeted treatments for psychiatric disorders in which impulsivity is a core issue.

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About the study

The study’s lead author was Emily Noble, formerly of USC Dornsife and now at the University of Georgia in Athens. Other collaborators were Zhuo Wang and Daniel Holschneider of Keck Medicine of USC as well as USC researchers Elizabeth Davis, Clarissa Liu, Andrea Suarez, Lindsey Schier and Linda Tsan.

The co-authors also included University of Illinois (Chicago) researchers Lauren Stein and Matthew Hayes; Michigan State University researchers Lauren Raycraft and Alexander Johnson; University of Pennsylvania researcher Ted Hsu; and University of Washington researcher Martin Darvas.

The work was supported largely by grants from the National Institutes of Health.