A new neural pathway for fear is described in a study in mice published online this week in Nature Neuroscience. The pathway is required for animals to retrieve previously formed fear memories.
The ability to learn associations between environmental cues and adverse outcomes is paramount to survival in any species. The amygdala, an almond-shaped structure deep within the brain, has a primary role in forming these types of fear memories. It has long been appreciated that the pathway from environmental cue to the amygdala is through the sensory areas of the neocortex, the same regions that enable an organism to decipher sounds, tastes, smells, and sights.
Yang Yang and colleagues now show that there is also a pathway in the brain operating in the opposite direction, from the amygdala back to the sensory neocortex. They find that changes in this pathway during learning are critical for remembering fearful stimuli and that inhibiting this pathway reduces a mouse’s fear response. To demonstrate this, the authors used a suite of tools and techniques that allow them to examine the microscopic structure of the pathway and to manipulate it in mice. These results have important implications for disorders that are associated with dysfunction of the amygdala, such as anxiety disorder and post-traumatic stress disorder.
As Bo Li writes in an accompanying News & Views article: “Undoubtedly ... the use of ever-advancing neuroscience technologies … holds promise for elucidating the neural mechanisms of fear regulation and dysregulation in health and disease, respectively.”