Brain switch that makes people addicted to alcohol, booze or cigarettes identified by scientists
Scientists say they’ve identified a brain switch that’s making people addicted alcoholdrugs and cigarettes.
The discovery opens the door to the development of treatments to fight addictions – such as opiate epidemic seizing the United States.
New York researchers exposed mice to a particular sound before giving them either a reward – sugar water – or a “punishment” – water.
Analyzes showed that key neurons in the amygdala began firing in response to noises, teaching the animals to associate them with a specific reward. But when these neurons were inhibited, the mice were unable to learn the meaning of the sounds.
The amygdala is the area of gray matter in the brain responsible for regulating human emotions. Everyone has two.
The pair work together to direct a response to a particular stimulus – like a sound – and to cause the release of dopamine when a reward is associated.
Regions help people learn and remember and are involved in the fight or flight response to a perceived threat.
In laboratory experiments, published in the journal Naturethe mice were exposed to a specific sound before being given a reward or punishment.
Using brain scans, the researchers found that the amygdala was stimulated in response to sounds.
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But they had a different answer depending on the type of sound. The scientists said this meant the mice had learned the meaning of each sound.
Over time, the scientists said the neuron’s response to sounds grew stronger.
In the next stage of the experiment, the scientists inhibited neurons in the amygdala.
They then repeated the tests using the same sounds and rewards or punishments.
But they found that mice couldn’t be trained to associate a sound with a particular reward or punishment without the neurons.
They also found that the brain’s normal dopaminergic response was suppressed.
Lead author Dr Bo Li, a neurologist who led the research, said: ‘This is entirely new to us.
“These neurons really care about the nature of each individual stimulus. It’s almost like a sensory zone.
He added: “While previous research had linked the central amygdala to dopamine neurons, it was unclear exactly how they were connected.”
“We discovered that these neurons are necessary for the normal functioning of dopaminergic neurons and are therefore important for learning rewards.
“This is direct evidence of how they regulate the function of dopaminergic neurons.”
Dr. Li and his colleagues now plan to examine the relationship between the amygdala and addiction.
Their trials are currently being conducted on mice but could eventually move on to other animals and humans.
Research could one day lead to better treatments for opioid and methamphetamine addiction.
Dr Li said: “Our study provides a basis for developing more specific ways to regulate these neurons in different pathological conditions.”
The United States is currently grappling with an opioid epidemic, with a record 108,000 Americans dead from overdoses.
The increase in deaths is attributed to fentanyl, which is up to 100 times more potent than morphine, mixed with other drugs, with people unaware that the drug they are using contains heroin.
There is also growing concern about mixing drugs with xylazine, an animal tranquilizer, against which the overdose drug naloxone does not work.
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