Cocaine.

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Rex Features / REX / SIPA

  • Researchers at the Timone Institute of Neuroscience recorded particular electrical activity in part of the brain of rats exhibiting compulsive behavior.

  • They found that by reproducing this electrical activity, individuals subsequently exhibited compulsive behavior.

  • It would thus be possible to act on this subthalamic nucleus in order to prevent these addictive behaviors.

A beginning of understanding of the mechanism of addiction in some people?

A team of neurobiologists from the Institut de neurosciences de la Timone, in Marseille, has just published on the PNAS (Proceedings of the National Academy of Sciences of the United States of America) site the results of an experiment carried out in rats. to understand the mechanism of drug addiction.

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The scope of the study

It starts from a simple observation for humans: how to understand these drive-type behaviors?

That is to say, to find out why a drug user continues to take them knowing the harmful effect on his health.

“The best example is the cigarette pack.

It is written roughly that "Smoking kills", and yet that does not prevent people from buying and consuming it.

It is this compulsive aspect ”, framework Mickaël Degoulet, researcher at CNRS and one of the authors of the study.

They therefore wondered if it was possible to find "a predictive mark" in the brain.

Study in rats

The team studied this behavior in rats, providing them with cocaine.

Then they randomly punished them during their drug search by applying a small electric shock to their paws.

“About 2/3 of the rats stopped searching for drugs because of the punishment.

But about 25% continued despite the possibility of the electric shock, ”explains the researcher.

The role of the subthalamic nucleus

Just before applying the punitive protocol, the researchers recorded electrical activity in the subthalamic nucleus, part of the brain.

“It is best known for its motor aspect, it is the preferred target for treating Parkinson's disease,” recalls Mickaël Degoulet.

And they recorded at the level of this nucleus a particular electrical activity in addicted rats, which is not present in individuals without this addictive attitude.

"The subthalamic nucleus sends a signal before and this activity at the level of this nucleus turns into compulsive behavior," he says.

Activation of this nucleus makes addict

To confirm this predictive aspect, the researchers studied the electrical signature, "the low frequencies of oscillation", in order to reproduce it and activate it in the subthalamic nucleus of individuals not exhibiting compulsive behavior.

“We found that people who were not compulsive became compulsive after activating this area.

And this, in spite of the protocol of punishments ”, underlines the researcher.

This confirms the predictive aspect of this area.

Perspectives

It is first of all interesting to note that approximately 25% of the rats studied develop some form of addiction, a proportion which is more or less the same in humans.

“Some people will drink alcohol every weekend without plunging into an addiction, and others will develop addictive behavior very quickly,” recalls Michaël Degoulet.

The main lesson lies in the possibility of influencing this area.

“The innovative part is this predictive signature, on which we can act by reducing compulsion in animals by reducing this deep stimulation.

Especially since we are already working in this area for Parkinson's disease.

It also remains to be seen whether it is possible to detect this activity in a non-invasive way, simply by putting on a helmet with electrodes, which could detect whether an individual is more vulnerable than another and therefore follow this individual upstream and make prevention, ”he says.

Vulnerability to other drugs

The study was based on the consumption of cocaine but it seems to indicate that the subthalamic nucleus also reacts with other drugs such as alcohol, nicotine or heroin.

“There is something interesting, and that is to understand why this pathological activity appears in some people and not in others.

There is an aspect on vulnerability, but what is happening at the cellular level, what kind of receptor or neurotransmitter are activated to better understand how these signals appear and how they join drug use, ”warns Michaël Degoulet.

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  • Addiction

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