Anxiety, depression, and social withdrawal are some of the most common mental health problems in the world. Millions of people struggle with these conditions, and scientists are still trying to understand exactly how they develop in the brain.
Now a new study has discovered that a very small group of brain cells may play a powerful role in controlling these emotions.
Researchers found that when these cells become too active, they can trigger behaviors linked to anxiety and social isolation. Even more surprising, the scientists showed that restoring balance in this small group of cells can reverse these behaviors.
The study was led by Juan Lerma and his team at the Institute for Neurosciences in Spain. Their findings were published in the scientific journal iScience.
The scientists focused on a brain structure called the amygdala. The amygdala is a small almond-shaped region deep inside the brain that plays a key role in processing emotions. It helps control feelings such as fear, stress, and emotional reactions to the world around us.
For many years, researchers have known that the amygdala is involved in anxiety and mood disorders, but it has been difficult to understand exactly which cells are responsible.
In this study, the team examined a specific group of neurons located in a part of the amygdala called the basolateral amygdala. Neurons are the brain’s communication cells. They send signals to each other to control thoughts, emotions, and behavior.
The researchers discovered that the activity of this small group of neurons can strongly influence emotional behavior. When these neurons become too active, they disturb the balance of signals in the brain. This imbalance can lead to behaviors that resemble anxiety, depression, and social withdrawal.
To study this process more closely, the scientists used genetically modified mice. These mice were designed to produce higher levels of a brain receptor called GluK4. This receptor is controlled by a gene known as Grik4. When too much GluK4 is produced, neurons become more excitable and send stronger signals than normal.
Because of this change, the communication between different parts of the brain becomes disrupted. The mice with this genetic change began to show clear signs of emotional problems.
They appeared anxious, avoided social contact, and behaved in ways similar to symptoms seen in some human mental health conditions such as autism, schizophrenia, and severe mood disorders.
After observing these behaviors, the researchers attempted to correct the problem. They used genetic tools to reduce the activity of the Grik4 gene only in the neurons of the basolateral amygdala. Importantly, they did not change other parts of the brain. They targeted only this small group of cells.
This single adjustment had a remarkable effect. Once the activity of the neurons returned to normal, communication between the basolateral amygdala and another group of neurons in a nearby area called the centrolateral amygdala was restored.
These neighboring neurons act as inhibitory cells, meaning they help calm down excessive brain activity. When the balance between these two groups of neurons returned, the emotional behavior of the mice also changed.
The anxious and antisocial behaviors largely disappeared. The mice became calmer and more willing to interact with other mice. According to Álvaro García, the first author of the study, this simple change was enough to reverse many of the emotional problems the animals had been showing.
The scientists confirmed their findings using detailed brain recordings known as electrophysiological measurements. These techniques allow researchers to study how neurons send electrical signals and communicate with each other.
The team also performed behavioral tests to measure anxiety and social behavior. For example, they tested whether mice preferred open spaces or stayed in enclosed areas, which is a common way scientists measure anxiety in animals. They also observed how much time the mice spent interacting with unfamiliar mice to evaluate social interest.
After the researchers restored the balance of neural activity, the mice behaved much more normally in these tests.
Interestingly, the researchers also tried the same treatment in ordinary mice that naturally showed higher levels of anxiety. The results were similar. Their anxiety decreased after the adjustment was made in the same brain region.
This suggests that the mechanism discovered in the study may not be limited to genetically modified animals. Instead, it may represent a more general way the brain controls emotional balance.
However, the scientists noticed that not all brain functions fully recovered. Some abilities related to memory, such as recognizing objects, did not completely improve. This suggests that other brain regions, including the hippocampus, may also play a role in emotional and cognitive disorders.
Even so, the study provides an important insight into how emotional disorders may arise from very specific disruptions in brain circuits.
In the past, most treatments for anxiety and depression have relied on medications that affect large areas of the brain. While these drugs can help many people, they often influence many different brain systems at once and may cause side effects.
This new research points toward a more precise approach. Future treatments might focus on correcting activity in very specific brain circuits rather than changing the chemistry of the entire brain.
If scientists can develop safe ways to target these overactive neurons, it may lead to new treatments that act faster and produce fewer side effects.
The research was supported by several Spanish and European funding agencies, including the Spanish State Research Agency, the Severo Ochoa Excellence Program, and the European Regional Development Fund.
The researchers say the next step will be to investigate whether the same brain mechanisms exist in humans and whether similar treatments could help people suffering from chronic anxiety, depression, or social disorders.
This discovery shows that even small changes in a tiny group of brain cells can have powerful effects on emotional behavior. As scientists continue to understand the brain’s complex circuits, new and more precise treatments for mental health conditions may become possible.
If you care about health, please read studies that scientists find a core feature of depression and this metal in the brain strongly linked to depression.
For more health information, please see recent studies about drug for mental health that may harm the brain, and results showing this therapy more effective than ketamine in treating severe depression.
Copyright © 2026 Knowridge Science Report. All rights reserved.
