Jerusalem, 17 March, 2026 (TPS-IL) — Sometimes habits and urges feel impossible to resist — but new research shows the brain may be hijacking itself. A team of Israeli and U.S. scientists has discovered that certain “conductor” cells can push serotonin, a key mood chemical, into overdrive, helping explain why compulsions, repetitive behaviors, or sudden mood swings can spiral out of control in conditions like Obsessive-Compulsive Disorder and depression.
The study, led by Prof. Joshua Goldberg of Hebrew University and Prof. Joshua Plotkin of New York’s Stony Brook University, focused on a small group of brain cells in the striatum called cholinergic interneurons. These cells were already known for their ability to trigger dopamine, a chemical that signals reward and motivation. When dopamine is released, it helps the brain recognize what actions are important or rewarding, fine-tuning learning and behavior.
The new research found that these same conductor cells can also directly trigger serotonin, a chemical closely linked to mood, anxiety, and compulsive behaviors. Using advanced optogenetic tools, which allow neurons to be turned on and off with light, the scientists observed that activating these conductor cells caused nearby serotonin fibers to release their signals almost instantly.
In brain states resembling Obsessive-Compulsive Disorder (OCD), the researchers found these cholinergic cells firing too often, driving excessive serotonin release. “In conditions like OCD, where cholinergic signaling may be dysfunctional, this normally helpful coordination may go into overdrive, which could help explain why certain behaviors become so difficult to stop,” Goldberg and Plotkin explained.
The study challenges the idea that psychiatric disorders result simply from having too much or too little of a single chemical. Instead, it suggests that the brain’s internal coordination system can amplify signals, creating cascading effects that disrupt normal behavior. Changes in acetylcholine signaling, the researchers note, can lead to parallel changes in both dopamine and serotonin, potentially contributing to the chemical imbalances seen in a variety of neurological and psychiatric conditions.
The discovery could lead to more precise treatments for psychiatric disorders. By targeting the acetylcholine system — the chemical trigger that drives serotonin release — researchers may develop drugs that adjust the brain’s signaling more accurately than current medications, which focus only on serotonin or dopamine.
Understanding how these conductor cells behave in individual patients could help doctors predict who will respond best to certain therapies, opening the door to personalized treatment plans. The findings may even inform behavioral interventions, allowing therapists to time exercises or coping strategies to coincide with periods when these brain cells are most active.
Globally, tens of millions of people live with serotonin-related conditions such as obsessive-compulsive disorder and depression, according to the World Health Organization and mental health studies.
“This discovery opens up new perspectives on how brain circuits interact to influence behavior and mood,” Goldberg said. “It could eventually inform more targeted approaches to treatment, beyond simply trying to adjust serotonin levels alone.”
The study was published in the peer-reviewed Nature Communications.
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