New research shows that our brains may be hardwired to become sensitive to stressful environments at an early age and, if overstimulated, this may contribute to anxiety disorders and even psychotic syndromes later in life.
The study, which appears in the journal Brain Structure and Function, focuses on two structures deep in the brain. The central nucleus of the amygdala (Ce) is thought to be involved in responses to immediate threats and stimulus, such as becoming startled or freezing in reaction to a loud noise. The bed nucleus of the stria terminalis (BST) is thought to be involved in regulating a person’s state of vigilance, such as determining whether or not an environment or a situation poses a potential threat. Animal and human studies show that when the BST is activated by a threatening situation, we tend to slow down, become quieter, and stress hormones spike.
While Ce and BST reside in different parts of the brain, the two areas are hardwired to each other by axonal tracts – basically, bundles of long distance axon fibers that enable the separate regions to communicate with each other. However, until now it has not been clear when these connections form or the way in which they interact with each other.
In the study published today, a team of researchers led by Julie Fudge, M.D., with the Department of Neuroscience observed that these connections are made at a very early stage of development in non-human primates. They also found that the direction of the connection is essentially a one way street. The Ce – or immediate fear signaling center – conveys information to the BST, the structure that mediates general threat sensing or anxiety states. This arrangement suggests that repeated activation of the Ce by immediately fearful or traumatic events may shape long-term anxiety states in the BST.