Researchers in Sweden have mapped the brain circuits responsible for repetitive and compulsive behaviours in mice, which can inform on disorders such as obsessive-compulsive disorder and addiction.  

Scientists at the EARA member Karolinska Institute used optogenetics, a technique that uses light to activate or inhibit neurons. The researchers controlled the function of neurons that connect two parts of the brain: the nucleus accumbens, the brain’s reward system, and the hypothalamus, which leads to a specific behaviour after receiving information from external and internal cues from other areas of the brain.  

Repeatedly activating the neurons connecting these two brain regions led the mice to perform repetitive behaviours, such as sniffing and digging, in the absence of any reward. By shutting off neurons in an area connected to the hypothalamus that perceives negative experiences, the mice stopped showing compulsive behaviour.  

“We have identified a brain circuit that can shift behavior into a repetitive mode. This helps us understand how compulsive actions arise and [these findings] may contribute to insights into conditions such as obsessive-compulsive disorder (OCD) and addiction,” said Konstantinos Meletis, co-leader of the study published in Science Advances.