Understanding Anxiety & Fear Conditioning Experiments

Experts believe that stress, anxiety, and fear all played important roles in human evolution. Now, though, these unpleasant, yet familiar, experiences can become pathological. Modern research into the neurobiology of these phenomena may help to provide relief for those suffering from anxiety disorders.

The problem is that anxiety & fear conditioning tests create ethical quandaries for researchers. Instead of learning about the neurobiology of anxiety, stress, and fear through human behavioral research, alone, researchers are also focused on mouse tests. Find out more about the most common anxiety & fear conditioning mouse tests below.
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How Stress Works in the Brain
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To understand the basis for anxiety & fear conditioning experiments, one first needs to know how these common pathologies affect the brain. To put it as simply as possible, stress affects the brain's central neuroendocrinological system, which is the part of the brain responsible for producing hormonal responses. When exposed to stress, the brain causes the pituitary gland to release a stress hormone called adrenocorticotropic hormone (ACTH).

The release of ACTH by the pituitary gland is also impacted by the activation of corticotropin-releasing factor (CRF) by the hypothalamus and the release of noradrenaline by the amygdala and hippocampus. The combined effect of all of these neurochemical reactions is to elicit specific cognitive and behavioral symptoms that people recognize as anxiety, stress, or fear.

Why Mice?

While mice may not have the cognitive abilities required to recognize the changes happening to their bodies and minds as a result of stress, their brains operate on the same basic neurobiological principles. Stress testing in mice allows researchers to gain a clearer understanding of how these mechanisms work without subjecting human test subjects to unpleasant, fear-inducing stimuli.
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How It Works
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Stress testing using mouse models involves creating mazes that expose the mice to at least one stress-inducing situation. One example can be seen in the elevated plus maze. To perform this test, researchers create a raised maze shaped like a plus sign and leave two of its arms exposed to the open air.

The mice placed in the maze face conflicting instinctual responses. They both want to explore new spaces and prefer to avoid elevated areas. The time that mice spend on the open-air arms can thus be seen as being anxiety-limited.

More Research Is Always Needed

Anxiety disorders negatively impact the lives of millions of people, and stress testing using mouse models has been proven repeatedly to be an excellent tool for the development of treatment options. Researchers can learn from their peers and choose paradigms for mouse stress and anxiety experiments that will further scientific knowledge of anxiety and inform future treatment approaches.