Stress can reduce our joy: Mouse brain patterns provide information on the reasons
Stress can reduce our joy: Mouse brain patterns provide information on the reasons
stresslessness creates a characteristic brain activity, such as a study on mice 1 . Research shows that there is a brain pattern that the Resilience compared to stress promotes - and another that makes stressed animals feel less likely to enjoy, a central symptom of depression.
These results, which were published in the journal Nature today, provide information on how the brain Anhedonie, resistance to joy . They also offer a new approach to the treatment of this disease if the results can be confirmed in humans.
"Your approach in this study is exactly right," says Conor Liston, a neuroscientist at the Weill Cornell Medicine in New York City, who was not involved in the study. The experiments close "a big gap," he notes. "Anhedonie is something that we don't understand well."
a stressful symptom
Over 70% of the people with Heavy Depression Experience Anhedonie, who also in people with Schizophrenie , Parkinson's and other neurological and psychiatric diseases.
This symptom is notoriously difficult to treat, even in patients who take medication, explains Liston. "Anhedonie is something that patients take care of, and what their opinion is the least taken into account by the current treatments," he adds.
To understand how the brain anhedonie produces, Mazen Kheirbek, a system neuroscientist at the University of California in San Francisco, and his colleagues mice that were exposed to stress by encountering larger, more aggressive mice.
Usually mice have a preference for sugar water and prefer this to the pure water if they have the choice. But instead, some stressed mice chose pure water - which Kheirbek and his colleagues interpreted as a typical form of anhedonia. Other mice that were exposed to the same stress preferred the sugar water. These animals were classified as "resilient".
The researchers then monitor neurons in the Amygdala and in the hippocampus, two brain regions that are important for the processing of emotions, in mice that had to decide between sugar water and pure water after the stress.
structure of a resilient brain
resilient mice had robust communication between Amygdala and Hippocampus, while in animals that were susceptible to anhedonia, communication between these two brain regions was fragmented.
In order to improve the torn communication in vulnerable mice, the researchers injected the rodents that led to neurons in the target areas more often. These animals decided more often after the injections than before, and their brain activity was more similar to that of the resilient mice, the authors found.
"It is very easy to stimulate part of the brain and damage it, but here a very mild stimulation lifts the activity slightly and increases a resilience sign," says Kheirbek.
reward -oriented behavior
rose Bagot, a neuroscientist at the McGill University in Montreal, Canada, which was not involved in the study, explains that the data show that there is a difference, such as resilient and susceptible mice process information about rewards. "People often think simplified by anhedonia as the inability to feel joy, but this study shows that it is more about changes in the ability to use information about reward to control behavior," she says.
A deeper understanding of these neuronal fire patterns has also produced a path to see which animals had a story of stress. In the case of resting mice, spontaneous activity in a certain part of the amygdala was a sign of former traumata . The authors suggest that this could serve as a biomarker for stress that would be more reliable than behavior, such as a reduced appetite behavior.
The answers to whether these results also apply to people could not be far away: therapeutic Electrodes that are implanted in the brains of people with epilepsy or treatment-resistant depression have also delivered data on brain activity. Liston says that after reading this study, he would see whether the data of people with these diseases confirm the results of the authors.
The researchers focused on the connection between Amygdala and Hippocampus, but Kheirbek plans to also examine other relevant brain regions, such as the prefrontal cortex, which plays a key role in regulating emotions. Bagot adds that it will be important to use a decision -making task that is more complicated than the choice between water types to model human behavior.
-
Xia, F. et al. Nature https://doi.org/10.1038/s41586-024-08241-Y (2024).