The fact that I no longer have to spend my life in a protective crouch has not eradicated that fear. It's a significant part of why I'm as shy and socially awkward as I am, and why I'm the guy at parties (if I get invited in the first place) who's standing there with a glass of scotch, looking around frantically for a dog to socialize with. I've tried for years to be okay with graciously accepting compliments when they come, and to open up to others about my interests, but to say it doesn't come naturally to me is a wild understatement.
This all comes up because of some research released last month from scientists at the RIKEN Center for Brain Science in Saitama, Japan. A team consisting of Ray Luo, Akira Uematsu, Adam Weitemier, Luca Aquili, Jenny Koivumaa, Thomas J.McHugh, and Joshua P. Johansen published a paper in Nature: Communications called "A Dopaminergic Switch for Fear to Safety Transitions," wherein we find out that a single neurotransmitter (dopamine) acting in a single part of the brain (the ventral tegmental area) is apparently responsible for unlearning fear responses.
The authors write:
Exposure therapy, a form of extinction learning, is an important psychological treatment for anxiety disorders such as post-traumatic stress disorder (PTSD). Extinction of classically conditioned fear responses is a model of exposure therapy. In the laboratory, animals learn that a sensory stimulus predicts the occurrence of an aversive outcome through fear conditioning. During extinction, the omission of an expected aversive event signals a transition from fear responding to safety. To switch from fear responding to extinction learning, a brain system that recognizes when an expected aversive event does not occur is required. While molecular changes occurring in the ventromedial prefrontal cortex (vmPFC) and amygdala are known to be important for storing and consolidating extinction memories, the brain mechanisms for detecting when an expected aversive event did not occur and fear responses are no longer appropriate are less well understood...
[Our] findings show that activation of VTA-dopamine neurons during the expected shock omission time period is necessary for normal extinction learning and the upregulation of extinction-related plasticity markers in the vmPFC and amygdala. Notably, inhibition of VTA-dopamine neurons during the shock period of fear conditioning facilitates learning, suggesting that activity in VTA-dopamine neurons is not simply important for learning in response to any salient event. These results also reveal that distinct populations of VTA-dopamine neurons... are important for the formation of stable, long-term extinction memories.Team leader Joshua Johansen was unequivocal about the potential for this research in treating long-term anxiety and PTSD. "Pharmacologically targeting the dopamine system will likely be an effective therapy for psychiatric conditions such as anxiety disorders when combined with clinically proven behavioral treatments such as exposure therapy," he said in a press release from RIKEN. "In order to provide effective, mechanism-based treatments for these conditions, future pre-clinical work will need to use molecular strategies that can separately target these distinct dopamine cell populations."
Illustration from Charles Darwin's Expression of the Emotions in Man and Animals (1872), captioned, "Terror, from a photograph by Dr. Duchenne." [Image is in the Public Domain]
I know it's a long way between identifying the brain pathway involved in a disorder and finding a way to alter what it's doing, but this is a significant first step. The idea that I might one day be able to go to social gatherings without feeling a sense of dread, and to talk to people rather than just dogs, is kind of amazing. Until that happens, I'm probably still going to have to deal with my anxiety, but it's nice to know someone is working on the problem.
This week's book recommendation is especially for people who are fond of historical whodunnits; The Ghost Map by Steven Johnson. It chronicles the attempts by Dr. John Snow to find the cause of, and stop, the horrifying cholera epidemic in London in 1854.
London of the mid-nineteenth century was an awful place. It was filled with crashing poverty, and the lack of any kind of sanitation made it reeking, filthy, and disease-ridden. Then, in the summer of 1854, people in the Broad Street area started coming down with the horrible intestinal disease cholera (if you don't know what cholera does to you, think of a bout of stomach flu bad enough to dehydrate you to death in 24 hours). And one man thought he knew what was causing it -- and how to put an end to it.
How he did this is nothing short of fascinating, and the way he worked through to a solution a triumph of logic and rationality. It's a brilliant read for anyone interested in history, medicine, or epidemiology -- or who just want to learn a little bit more about how people lived back in the day.
[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]