Discovery of a Neural Pathway Underlying Fear Memories from Psychological Threats

Researchers from KAIST have uncovered a specific neural circuit responsible for forming fear memories triggered by psychological threats, advancing our understanding of mental health disorders like PTSD and anxiety. Traditionally, fear memories were associated with physical pain or direct harm, but this new study highlights how emotional distress alone can create lasting fear responses. The team identified the pIC-PBN pathway, a descending neural circuit from the posterior insular cortex (pIC) to the parabrachial nucleus (PBN), which transmits threat information unrelated to physical pain. This pathway was previously unknown in its role in processing emotional fear, challenging the conventional view of PBN solely as part of the pain pathway. Conducting experiments on mice, scientists used visual threat stimuli instead of painful shocks, mimicking real-world psychological stressors. Using chemogenetic and optogenetic methods, they demonstrated that inhibiting this circuit reduces fear memory formation, while activating it induces fear responses, illustrating its pivotal role in emotional fear processing. The research offers insights into how emotional and physical pain are processed via separate neural pathways and opens new possibilities for targeted therapies for trauma-related conditions. As Dr. Junho Han explains, understanding this circuit could lead to innovative treatments for mental health disorders rooted in psychological distress, beyond physical injury or pain. This groundbreaking work was published in Science Advances and represents a significant step toward decoding the complex neural mechanisms behind fear memory formation from psychological threats.