summary: Scientists have shown for the first time how alcohol use can lead to long-term cognitive impairment by damaging brain circuits that cause decision-making. In the rat model, animals exposed to high alcohol levels were significantly worsened with complex, shifting reward tasks, even after nearly 3 months of drinking.
These decision deficits were linked to weakening of neural activity in the dorsal medial striatum, which is important for assessing selection. Findings suggest that alcohol-induced brain changes may underlie poor judgment and recurrence in people with alcohol use disorders.
Important facts:
- Persistent damage: Alcohol-exposed rats showed decision-making impairment several months after withdrawal.
- Targeted brain influence: Damage was found in the dorsal medial striatum, a decision-making hub.
- Gender differences have been pointed out: Effects were seen in male rats, but not women, suggesting sex-based variability.
sauce: jhu
Researchers are the first to show in animals how alcohol use can lead to long-term behavioral problems by damaging brain circuits, which are important for decision-making.
Rats exposed to heavy alcohols showed poor decision-making during complex tasks, even after a few months of withdrawal period. Important areas of their brains were subjected to dramatic functional changes compared to healthy rats.
Survey results published today Advances in scienceprovides a new explanation of the long-term effects of alcohol on cognition.
“There is a new model of unfortunate cognitive changes that humans with alcohol use disorders currently exhibit,” says author Patricia Janack, a neuroscientist at Johns Hopkins University who studies addiction biology.
“We know that people who are obsessed with alcohol can demonstrate learning and decision-making flaws that could contribute to poor decisions related to alcohol use. Animal models were needed to better understand how chronic alcohol abuse affects the brain.
“Knowing what is happening when an animal’s brain has these decision-making challenges tells us what is happening in humans.”
In an experiment led by first author Yifeng Chen, a research scientist in Janac’s lab studying the effects of alcohol on the brain, rats received extremely high alcohol exposure for a month. Thereafter, after a withdrawal period of nearly three months, rats were given a reward-based decision-making test along with a control group of non-alcoholic rats.
To earn reward, the rats were given a choice of two levers. Pushing one lever gives you a more reward chance than pushing the other lever. Rats can easily learn which levers provide the most reward, allowing researchers to get complicated every few minutes and switch which levers have the best reward likelihood.
To get the most reward, a mouse should rapidly change its behavior each time it realizes that the likelihood of a reward has changed.
Requiring memory and strategy was a difficult task. Alcohol-exposed rats have been significantly worse.
Previous experiments with animals were not comparable to humans with alcohol use disorders, as the animals did not show rapid decision-making defects. The team believes this is because the tasks in previous experiments were too simple.
“Our experiments were very challenging and even rats exposed to alcohol couldn’t do that,” Janack said.
“When the correct answers were constantly changing, control rats made the best decision faster. They were more strategic. And as we looked at their brains, the decision-making-related neural signals in control rats became stronger.”
The team linked behavioral difficulties with a dramatic functional transformation of the dorsal medial striatum, a part of the brain that is important for decision-making. Alcohol damages neural circuits, causing rats exposed to alcohol to process information more effectively.
One surprise was how long the alcohol dependence impaired cognitive and neural function even after retreat.
“This may provide insight into why recurrence rates are so high among alcoholic people,” Janack said. “Alcohol-induced neuropathy can contribute to the decision to drink even after going to rehabilitation. It can clearly show that these defects can last long.”
The team only found behavioral and neurological disorders in male rats. The team does not believe this suggests that female rats are immune to alcohol effects, but they believe that there may be sex-related sensitivity to long-term alcohol effects on brain function.
Second, the researchers hope to explore how alcoholism affects other areas of the brain that interact with the dorsal striatum, and how it can cause differences between men and women.
Other authors include Robin Magnard, a postdoctoral researcher at Johns Hopkins. Angela J. Langdon of the National Institutes of Health. and Dial Lee, a well-known professor at Johns Hopkins’ neuroscience and psychological and neuroscience at Bloomberg.
About this AUD and Cognitive Research News
author: Jill Rosen
sauce: jhu
contact: Jill Rosen – Je
image: This image is credited to Neuroscience News
Original research: Open access.
“Chronic ethanol exposure causes sex-dependent disorders in striatal value calculations“Patricia Janack et al. Advances in science
Abstract
Chronic ethanol exposure causes sex-dependent disorders in striatal value calculations
Value-based decision-making relies on the striatum where neuroplasticity changes due to chronic ethanol (ETOH) exposure, but the effect of such plasticity on striatal neural dynamics during decision-making remains unknown.
This study used a dynamic stochastic inversion learning task to investigate the long-term effects of ETOH on reward-driven decision-making and striatal neural calculations in male and female rats.
After a long period of withdrawal, male rats exposed to EtOH updated abnormal outcome-driven values that increased preference for selected behavior, showing defects in adaptive and exploratory behavior.
These behavioral changes were associated with altered neural activity in the dorsal medial striatum (DMS), with ETOH increasing outcome-related encodings and decreasing selection-related encodings. In contrast, female rats showed minimal behavioral changes with distinct EtOH-induced changes in neural activity, revealing significant gender differences in the effects of chronic ETOH.
Our findings highlight the effects of chronic EtOH exposure on adaptive decision making, revealing the persistent changes in neural computational processes in the striatum, which underlie cognitive impairments that differ from sex to sex.
