Illustration of reward pathways in the human brain
Fernando da Cunha/Science Photo Library
Continuous use of drugs such as cocaine and morphine is thought to affect the way the brain prioritizes the body’s basic needs, and we are now learning more about how this happens.
When people repeatedly abuse drugs, they may see long-term changes in their behavior that lead them to choose to take drugs instead of doing basic things like eating.
A brain pathway called the mesolimbic reward system is suspected to be involved in this process, but few studies have directly compared this system’s response to taking drugs with its response to satisfying innate needs.
Now, Chen Bowen The professor at Rockefeller University in New York and his colleagues showed that the same neurons are activated in both conditions. They discovered this using a sophisticated microscopy setup that allowed them to track the activity of individual neurons in the brains of mice experiencing withdrawal after repeated exposure to these drugs.
“The field has long debated whether there is a special cell type that encodes only the value of drugs and a special cell type that only encodes the value of natural rewards,” Tan said. “What we see is that these drugs of abuse often activate the same set of neurons as natural rewards.”
The researchers also observed that when mice were given cocaine or morphine, neural responses to basic needs were disrupted, along with reduced food and water consumption.
“What’s really remarkable about this finding is that the strong neural response to food or water was almost replaced by a response to the drug,” said Jeremy Day at the University of Alabama at Birmingham. “(This shows) that drug rewards can override the way the brain translates need states into behaviors that satisfy those needs.”
Tan and his team also discovered a gene called Rebwhich appears to be necessary for the drug to produce this effect. Reb It’s part of a cell signaling pathway that’s also found in humans, so future work could investigate how to inhibit that pathway as a treatment for drug abuse, he said.
Blissfulcalmways
