143 lines
6.1 KiB
Markdown
143 lines
6.1 KiB
Markdown
---
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created_at: '2016-09-08T08:12:26.000Z'
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title: Brain Is a Co-Conspirator in a Vicious Stress Loop (2009)
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url: http://www.nytimes.com/2009/08/18/science/18angier.html?em
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author: jimsojim
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points: 61
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story_text:
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comment_text:
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num_comments: 17
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story_id:
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story_title:
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story_url:
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parent_id:
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created_at_i: 1473322346
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_tags:
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- story
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- author_jimsojim
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- story_12451152
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objectID: '12451152'
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year: 2009
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---
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Robert Sapolsky, a neurobiologist who studies stress at Stanford
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University School of Medicine, said, “This is a great model for
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understanding why we end up in a rut, and then dig ourselves deeper and
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deeper into that rut.”
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The truth is, Dr. Sapolsky said, “we’re lousy at recognizing when our
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normal coping mechanisms aren’t working. Our response is usually to do
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it five times more, instead of thinking, maybe it’s time to try
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something new.”
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And though perseverance can be an admirable trait and is essential for
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all success in life, when taken too far it becomes perseveration —
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uncontrollable repetition — or simple perversity. “If I were to try to
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break into the world of modern dance, after the first few rejections the
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logical response might be, practice even more,” said Dr. Sapolsky, the
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author of “Why Zebras Don’t Get
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[Ulcers](http://health.nytimes.com/health/guides/disease/gastric-ulcer/overview.html?inline=nyt-classifier "In-depth reference and news articles about Ulcers."),”
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among other books. “But after the 12,000th rejection, maybe I should
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realize this isn’t a viable career option.”
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Photo
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Happily, the stress-induced changes in behavior and brain appear to be
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reversible. To rattle the rats to the point where their stress response
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remained demonstrably hyperactive, the researchers exposed the animals
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to four weeks of varying stressors: moderate electric shocks, being
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encaged with dominant rats, prolonged dunks in water. Those chronically
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stressed animals were then compared with nonstressed peers. The stressed
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rats had no trouble learning a task like pressing a bar to get a food
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pellet or a squirt of sugar water, but they had difficulty deciding when
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to stop pressing the bar, as normal rats easily did.
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But with only four weeks’ vacation in a supportive setting free of
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bullies and Tasers, the formerly stressed rats looked just like the
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controls, able to innovate, discriminate and lay off the bar. Atrophied
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synaptic connections in the decisive regions of the prefrontal cortex
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resprouted, while the overgrown dendritic vines of the habit-prone
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sensorimotor striatum retreated.
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According to Bruce S. McEwen, head of the neuroendocrinology laboratory
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at Rockefeller University, the new findings offer a particularly elegant
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demonstration of a principle that researchers have just begun to grasp.
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“The brain is a very resilient and plastic organ,” he said. “Dendrites
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and synapses retract and reform, and reversible remodeling can occur
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throughout life.”
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## Newsletter Sign Up
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[Continue reading the main story](#continues-post-newsletter)
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Stress may be most readily associated with the attosecond pace of
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postindustrial society, but the body’s stress response is one of our
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oldest possessions. Its basic architecture, its linked network of neural
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and endocrine organs that spit out stimulatory and inhibitory hormones
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and other factors as needed, looks pretty much the same in a goldfish or
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a red-spotted newt as it does in us.
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The stress response is essential for maneuvering through a dynamic world
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— for dodging a predator or chasing down prey, swinging through the
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trees or fighting off disease — and it is itself dynamic. As we go about
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our days, Dr. McEwen said, the biochemical mediators of the stress
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response rise and fall, flutter and flare.
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“[Cortisol](http://health.nytimes.com/health/guides/test/cortisol-level/overview.html?inline=nyt-classifier "In-depth reference and news articles about Cortisol level.")
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and adrenaline go up and down,” he said. “Our inflammatory cytokines go
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up and down.”
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Advertisement
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[Continue reading the main story](#story-continues-4)
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The target organs of stress hormones likewise dance to the beat: blood
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pressure climbs and drops, the heart races and slows, the intestines
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constrict and relax. This system of so-called allostasis, of maintaining
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control through constant change, stands in contrast to the mechanisms of
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homeostasis that keep the pH level and oxygen concentration in the blood
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within a narrow and invariant range.
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Unfortunately, the dynamism of our stress response makes it vulnerable
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to disruption, especially when the system is treated too roughly and not
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according to instructions. In most animals, a serious threat provokes a
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serious activation of the stimulatory, sympathetic, “fight or flight”
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side of the stress response. But when the danger has passed, the calming
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parasympathetic circuitry tamps everything back down to baseline
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flickering.
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In humans, though, the brain can think too much, extracting phantom
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threats from every staff meeting or high school dance, and over time the
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constant hyperactivation of the stress response can unbalance the entire
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feedback loop. Reactions that are desirable in limited, targeted
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quantities become hazardous in promiscuous excess. You need a spike in
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blood pressure if you’re going to run, to speedily deliver oxygen to
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your muscles. But chronically elevated blood pressure is a source of
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multiple medical miseries.
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Why should the stressed brain be prone to habit formation? Perhaps to
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help shunt as many behaviors as possible over to automatic pilot, the
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better to focus on the crisis at hand. Yet habits can become ruts, and
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as the novelist Ellen Glasgow observed, “The only difference between a
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rut and a grave are the dimensions.”
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It’s still August. Time to relax, rewind and remodel the brain.
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[Continue reading the main story](#whats-next)
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