Nov 24, 2024 22:00:00

It has been revealed that the amygdala, a region of the brain associated with anxiety and depression, differs in some areas between humans and non-humans such as monkeys

The amygdala, which is responsible for emotional processing in the brain, has been pointed out as a possible cause of depression, as well as fear and anxiety. However, the amygdala is still poorly understood, and scientists sometimes study the amygdala of non-human primates such as rhesus monkeys. A research team at the University of California, Davis confirmed that different cells are activated in the gene expression patterns in the amygdala of humans and non-human primates.

Translational Insights From Cell Type Variation Across Amygdala Subnuclei in Rhesus Monkeys and Humans | American Journal of Psychiatry
https://psychiatryonline.org/doi/10.1176/appi.ajp.20230602

The Roots of Fear: Understanding the Amygdala | UC Davis

https://www.ucdavis.edu/news/roots-fear-understanding-amygdala

According to Drew Fox, an associate professor of psychology at the University of California, Davis, the amygdala is the center of emotional processing in the brain and is known to contribute to fear and anxiety, and there has long been interest in whether variations in the size and structure of the amygdala are related to disorders such as anxiety and depression. However, previous studies have shown that the size and structure of the amygdala are not related to neuropsychological problems such as depression.

Studies on rodents have also shown that different regions of the amygdala contain different cells than those in humans, but identifying which cells cause neuropsychological problems in humans and other primates has been difficult, and the cellular environment of the amygdala in primates has remained largely unexplored.

The team took samples from human and rhesus monkey brains, isolated individual cells, and then sequenced their RNA. This shows which genes are active in specific cells, allowing them to group cells based on their gene expression. 'By clustering cells based on their gene expression, we can identify cell types and their developmental origins,' Fox said.

In their study, the team identified a group of cells called 'intercalated cells' at the edge of the amygdala to express a gene called '

FOXP2 ', and demonstrated that in rodents, this group of cells acts as a 'gatekeeper' that controls signal traffic in and out of the amygdala. This discovery suggests that intercalated cells may be a powerful tool for developing treatments for FOXP2 disorders.

In addition, this research will help identify the cells that will be targeted by the administered drug. Specifically, cells that express FOXP2 tend to express both anxiety-related genes and a receptor called neuropeptide FF receptor 2 ( NPFFR2 ), which could lead to the development of drugs that activate only NPFFR2 as a potential target for anxiety-related disorders, creating new treatment strategies.

The team also identified both similarities and differences between the human amygdala and that of non-human primates, findings that could be important for understanding how animal models of conditions such as anxiety and autism relate to humans.

'Anxiety is a complex disorder that can manifest in many different ways,' said Fox. 'By better understanding the types of cells involved, we may be able to identify and treat the 'chokepoints' that affect many people. We want to know which cells to target in order to develop drugs that target the amygdala.'