A new pathway that controls fear memories and behavior in mouse has been found. Fear is encoded in neural circuits and is stored in a specific part of the brain, in the central amygdala. The researchers, led by associate professor Bo Li, of Cold Spring Harbor Laboratory, wanted to find out what controls the amygdala.

The research found that a cluster of neurons that forms the paraventricular (PVT) nucleus of the thalamus was activated as animals recalled fear memories or learned to fear. Published in Nature, the study saw neurons extending from the PVT to the central amygdala. Disturbing this connection significantly impairs fear-learning.

The connection between the PVT and the central amygdala is a potential therapeutic agent since any impairment in it causes a problem in fear-learning.

To identify the connection, the researchers looked at data from people with post-traumatic stress disorder. They were looking for a chemical messenger that might link the two structures. The molecule BDNF was the ideal candidate because it is associated with anxiety disorders. BDNF stimulates the birth of new neurons and connections between neurons. Patients with anxiety disorders have mutations in BDNF.

The research found that introducing BDNF in the central amygdala activates its neurons, triggering a fear response in animals that have not previously been exposed to fear stimulants and forming long-term fear memories in animals.

Thus, the researchers learned to control fear in mice using BDNF. BDNF molecule is the chemical messenger that allows the PVT to control the central amygdala.

It may be possible to control fear in people by controling BDNF, but this has not yet been tested. If it is a control circuit for fear in peopl, this method can be used to treat anxiety disorders.

About 40 million adults suffer from anxiety disorders.

To contact the writer, email: sonali.raj@gmail.com