Inside the Brain’s Threat Response

Infralimbic parvalbumin neural activity facilitates cued threat avoidance

A new study published in eLife reveals that a specific group of inhibitory neurons called parvalbumin (PV) interneurons in the infralimbic cortex (IL) plays a pivotal role in helping mice actively avoid danger. Conducted by researchers from Cornell University, the University of Arizona College of Medicine, and the University of Arizona, the study uncovers a neural mechanism that enables animals to override their instinct to freeze in response to threats.

The researchers found that these PV neurons become active when mice begin to avoid an impending shock, rather than freezing in fear. Remarkably, this neural activity emerges after just a single shock experience, before the avoidance behavior is even fully learned.

To explore this further, the team used optogenetics, employing the Cobolt Mambo 594 nm laser to precisely control neuronal activity. When PV neurons were suppressed, mice exhibited increased freezing and delayed avoidance responses. Importantly, these neurons did not activate during reward-seeking or general movement, highlighting their specific role in threat avoidance.

This discovery challenges the traditional view of inhibitory neurons as mere suppressors of brain activity. Instead, it positions them as key players in flexible, adaptive behavior, a finding with potential implications for understanding anxiety disorders, PTSD, and resilience.