These studies provide evidence for a multi-neuron link between brain regions controlling cognition and those regulating hormonal output of the stress system. The consequences of prolonged stress can range from general malaise to physical or mental illness. The mechanisms controlling stress remain poorly defined, and our studies aim to establish how the brain controls stress responses. Herman and colleagues believe the brain's stress circuitry is driven by inhibition of certain chemicals, rather than excitation. For instance, say you walk by a cave 50 times, and nothing comes out.
Inhibitory systems engage to prevent generation of an unneeded, metabolically expensive response.
On walk number 51, however, a bear jumps out at you. The way it does that is through overcoming the ongoing inhibition of the system. The delicate balance between stress inhibition and excitation is a survival strategy built into animals through millions of years of evolution, allowing responses to be generated on demand and quickly turned off. Problems arise when the system gets changed to such an extent that the animal no longer is able to activate the inhibition, which means more stress hormones are released into the body and brain. The paraventricular nucleus.