Experts have known that fear memories are learned and stored in a part of the brain known as the amygdala. This learned memory can serve as a healthy defense in dangerous situations, but in some cases, these memories become too powerful and invasive and can lead to post-traumatic stress disorder (PTSD). In exciting new research conducted at Cold Spring Harbor Laboratory, funded in part with a NARSAD Grant, new insights have been gained about the brain activity involved when fear memories control behavior.
In 2013, Cold Spring Harbor Laboratory Associate Professor and 2010 NARSAD Young Investigator Grantee, Bo Li, Ph.D., and his team used a novel genetic technique, known as optogenetics, to determine the exact neurons in the central amygdala that control fear memory. On February 12th in The Journal of Neuroscience, a new study by Dr. Li and colleagues was published identifying a group of long-range neurons that extend from the central amygdala out to an area of the brainstem which controls the fear response.
It has been well understood that when a person experiences a disturbing event, neurons are activated in the amygdala, sending a signal from one group of neurons to the next (synaptic transmission), that ultimately reaches the brainstem, where the fear memory is translated into action. The precise mechanism through which this translation of fear memory into action occurs has remained a mystery. Dr. Li and colleagues discovered a new neural circuit in the brain that directly links the site of fear memory with an area of the brainstem that controls behavior.
To study this phenomenon, the researchers trained animals to fear a sound by associating it with a shock. With new technologies, they were then able to observe the corresponding brain activity and discovered that long-range projection neurons in the central amygdala directly contact neurons in the brainstem.
“This study not only establishes a novel pathway for fear learning, but also identifies neurons that actively participate in fear conditioning,” says Dr. Li. The team’s next step is to apply this new knowledge to models of PTSD. “We are working to find out how these circuits behave in anxiety disorders, so that we can hopefully learn to control fear in diseases such as PTSD.”
Learn more about this research.
Read an abstract of this research study.