Scientists identify the brain switch that makes people addicted to alcohol, drugs or cigarettes
Scientists say they have identified a brain switch that makes people addicted to alcohol, drugs and cigarettes.
This discovery opens the door to the development of treatments to combat addiction – much like the opioid epidemic sweeping the United States.
Researchers in New York exposed rats to a specific sound before giving them a reward – sugar water – or “punishment” water.
The scan showed that key neurons in the amygdala began firing in response to the noise, teaching the animals to associate it with a specific reward. But when these neurons were inhibited, the mice could not tell the meaning of the sounds.
The above scan shows the amygdala inside a mouse brain (red dot on the left). Humans and mice exhibit this brain structure
The amygdala is the gray matter region of the brain responsible for regulating human emotions. Everyone has two.
The pair work together to direct a response to a specific stimulus — such as a sound — and to induce the release of dopamine when a reward is associated.
Areas help people learn, remember, and participate in the fight-or-flight response to a perceived threat.
in laboratory experiments, Published in the journal NatureMice were exposed to a specific sound before receiving a reward or punishment.
Using brain scans, the researchers found that the amygdala is stimulated in response to sounds.
But they had a different response depending on the type of sound. The scientists said this meant the rats learned the meaning of each sound.
Over time, the scientists said, the response of nerve cells to sounds became stronger.
In the next stage of the experiment, the scientists inhibited neurons in the amygdala.
Then they repeated the tests using the same sounds and rewards or punishments.
But they found that the rats could not be trained to associate the sound with a specific reward or punishment without the neurons.
They also found that the brain’s normal response to dopamine was suppressed.
This is completely new for us, said lead author Dr Bo Li, a neurologist who led the research.
These neurons really care about the nature of each individual stimulus. It’s almost like the sensory area.
He added, “While previous research has linked the amygdala to dopamine neurons, it is not clear exactly how they are connected.
We have found that these neurons are required for the normal function of dopamine neurons, and are therefore important for reward learning.
This is direct evidence of how they regulate the function of dopamine neurons.
Dr. Lee and his colleagues now plan to study the relationship between the amygdala and addiction.
They are currently being tested in mice, but may eventually progress to other animals and humans.
The research could one day lead to better treatments for opioid and methamphetamine addiction.
For the experiment, the rats heard a signal before they were given water or sucrose. The scans showed that they learned to associate certain sounds with specific rewards or punishments
“Our study provides a basis for developing more specific ways to regulate these neurons in different disease states,” said Dr. Lee.
The United States is currently in the grip of an opioid epidemic, in which 108,000 Americans have died from overdoses.
The increased deaths have been attributed to fentanyl, which is up to 100 times more powerful than morphine, as it mixes with other drugs with people not realizing that the drug they are using contains heroin.
There are also growing concerns about the drugs being mixed with xylazine, an animal tranquilizer, which naloxone does not work against.
(tags to translate) Daily Mail