Decoding the Neuroscience of Fear and Fearlessness
New findings on the amygdala offer clues to overcoming fear, anxiety, and panic.
Posted February 6, 2013
The amygdala and fear-processing.
The pathways through which we consciously and subconsciously interpret fear are not well understood by neuroscientists. This week two new studies were released about the amygdala and its role in fear and fearlessness. As with many advances in science, it appears the more we know about the amygdala, the less we actually understand how it works.
In the first study, released on January 27, 2013 scientists identified specific neurons linked to a certain type of fear memory held in your amygdala. The neuroscience group at Cold Spring Harbor Laboratory (CSHL) led by Assistant Professor Bo Li Ph.D. released a study that examines how fear responses are learned, controlled, and memorized. They found that a specific class of neurons called SOM+ in a subdivision of the amygdala plays an active role in these processes.
In another paper published February 3, 2013 in the journal Nature Neuroscience, a University of Iowa team showed that the amygdala is not the only gatekeeper of fear in the human mind. Other regions—such as the brainstem, diencephalon, or insular cortex—could sense the body's most primal inner signals of danger when basic survival is threatened.
"This research says panic, or intense fear, is induced somewhere outside of the amygdala," says John Wemmie, associate professor of psychiatry at the University of Iowa and senior author on the paper. "This could be a fundamental part of explaining why people have panic attacks."
"Information from the outside world gets filtered through the amygdala in order to generate fear," added first author Justin Feinstein, a clinical neuropsychologist who earned his doctorate at the UI last year. "On the other hand, signs of danger arising from inside the body can provoke a very primal form of fear, even in the absence of a functioning amygdala."
Overcoming Fear: Whether to Freeze, Flee, or Fight?
Fear can make you run and hide, it can motivate you to take action, and it can freeze you dead in your tracks. In a 2010 study published in Neuron, scientists in Italy at the European Molecular Biology Laboratory (EMBL) and Glaxo Smith Kline in Verona identified that a specific type of neurons in the amygdala determine how mice react to a frightening stimulus. Their findings revealed that deciding whether or not to freeze when you are faced with fear is a much more complex task for our brains than was formerly realized.
The scientists found that when they inhibited certain neurons in the amygdala of mice they were able to switch the response to fear from a passive stance to a more active one. Do human beings have the same response? Can we consciously condition ourselves to be more active and less passive in the face of fear? I believe the answer is yes.
"When we inhibited these neurons, I was not surprised to see that the mice stopped freezing because that is what the amygdala was thought to do. But we were very surprised when they did a lot of other things instead, like rearing and other risk-assessment behaviors," says Cornelius Gross, who led the research at EMBL, "it seemed that we were not blocking the fear, but just changing their responses from a passive to an active coping strategy. That is not at all what this part of the amygdala was thought to do."
Much to their surprise, the researchers found that the change from a passive to an active fear response was accompanied by the activation of large parts of the outer layer of the cerebrum called "the cortex." Blocking this activation of the cortex could reinstate freezing behavior and flip the fear switch back to being passive.
This finding stumped many scientists who study fear circuitry, because the amygdala was thought to control fear via the brainstem, not the cortex. Humans also show freezing and risk-assessment behaviors in response to fear. Understanding how to switch from passive to more active fear coping strategies is key to adapting to the stress and unpredictability of modern life, the scientists say.
Taking a multi-pronged approach to anxiety disorders.
Peter Norton, associate professor in clinical psychology and director of the Anxiety Disorder Clinic at the University of Houston (UH) found that patients suffering from anxiety disorders showed the most improvement when treated with cognitive-behavioral therapy (CBT) in conjunction with a "transdiagnostic" approach, which is a model that allows therapists to apply one set of principles across anxiety disorders. The findings are the result of a decade of research, four separate clinical trials and the completion of a five-year grant funded by the National Institute of Mental Health.
Norton defines anxiety disorders as when anxiety and fear are so overwhelming that it can start to negatively impact a person's day-to-day life. He states that anxiety disorders include: panic disorder, obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), social anxiety disorder, specific phobias and generalized anxiety disorder.
Often anxiety disorders occur with a secondary trait, such as depression, substance or alcohol abuse. Norton says there are targeted treatments for each diagnosis, but there has been little recognition that the treatments don't differ much.
"The Diagnostic and Statistical Manual of Mental Disorders (DSM) has been an important breakthrough in understanding mental health, but people are dissatisfied with its fine level of differentiation," said Norton. "Panic disorders are considered something different from social phobia, which is considered something different from PTSD. The hope was that by getting refined in the diagnosis we could target interventions for each of these diagnoses, but in reality that just hasn't played out."
Norton finds cognitive-behavioral therapy (CBT), a type of treatment with a specific time frame and goals, helps patients understand the thoughts and feelings that influence behaviors is the most effective treatment. The patients receiving the transdiagnostic treatment showed considerable improvement.
Norton states, "What I have learned from my past research is that if you treat your principal diagnosis, such as social phobia and you hate public speaking, you are going to show improvement on some of your secondary diagnosis. Your mood is going to get a little better, your fear of heights might dissipate."
The transdiagnostic treatment approach is more efficient in treating the whole person rather than just treating the diagnosis, and then treating the next diagnoses... Norton notes that the biggest contribution of his studies is to further guide the development and interventions for how clinical psychologists, therapists and social workers can treat people with anxiety disorders. He hopes that the data collected from his research will be useful for people on the front lines to effectively and efficiently treat people to reduce anxiety disorders.