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  • Are you sleeping restlessly, feeling irritable or moody, forgetting little things, and feeling overwhelmed and isolated?


  • Don't worry; we've all been there.


  • You're probably just stressed out.


  • Stress isn't always a bad thing.


  • It can be handy for a burst of extra energy and focus, like when you're playing a competitive sport or have to speak in public.


  • But when its continuous, the kind most of us face day in and day out, it actually begins to change your brain.


  • Chronic stress, like being overworked or having arguments at home, can affect brain size, its structure, and how it functions right down to the level of your genes.


  • Stress begins with something called the "hypothalamus pituitary adrenal axis", a series of interactions between endocrine glands in the brain and on the kidney, which controls your body's reaction to stress.

    壓力源自於「下視丘-腦垂體-腎上腺軸」(簡稱 HPA軸),在大腦和腎中的內分泌腺一系列的相互作用後,會控制身體對壓力做出反應。

  • When your brain detects a stressful situation, your HPA axis is instantly activated and releases a hormone called "cortisol", which primes your body for instant action.

    當大腦偵測到壓力狀態,HPA 軸會立即啟動並釋放「皮質醇」荷爾蒙,使身體準備好做出立即的反應。

  • But high levels of cortisol over long periods of time wreak havoc on your brain.


  • For example, chronic stress increases the activity level and number of neural connections in the amygdala, your brain's fear center.


  • And as levels of cortisol rise, electric signals in your hippocampusthe part of the brain associated with learning, memories, and stress controldeteriorate.


  • The hippocampus also inhibits the activity of the HPA axis, so when it weakens, so does your ability to control your stress.

    海馬迴也會抑制 HPA 軸的活動,所以當它削弱時,你控制壓力的能力亦會下降。

  • That's not all, though.


  • Cortisol can literally cause your brain to shrink in size.


  • Too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex, the part of your brain that regulates behaviors like concentration, decision-making, judgment, and social interaction.


  • It also leads to fewer new brain cells being made in the hippocampus.


  • This means chronic stress might make it harder for you to learn and remember things, and also set the stage for more serious mental problems, like depression and, eventually, Alzheimer's disease.


  • The effects of stress may filter right down to your brain's DNA.

    壓力的影響可能直接滲透至大腦的 DNA。

  • An experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life.


  • The pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors, which stick to cortisol and dampen the stress response.


  • The pups of negligent moms had the opposite outcome, and so, became more sensitive to stress throughout life.


  • These are considered "epigenetic changes", meaning that they affect which genes are expressed without directly changing the genetic code.


  • And these changes can be reversed if the moms are swapped.


  • But there's a surprising result.


  • The epigenetic changes caused by one single mother rat were passed down to many generations of rats after her.


  • In other words, the results of these actions were inheritable.


  • It's not all bad news, though.


  • There are many ways to reverse what cortisol does to your stressed brain.


  • The most powerful weapons are exercise and meditation, which involves breathing deeply and being aware and focused on your surroundings.


  • Both of these activities decrease your stress and increase the size of the hippocampus, thereby improving your memory.


  • So, don't feel defeated by the pressures of daily life.


  • Get in control of your stress before it takes control of you.


Are you sleeping restlessly, feeling irritable or moody, forgetting little things, and feeling overwhelmed and isolated?


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B1 中級 中文 美國腔 TED-Ed 壓力 皮質醇 大腦 海馬迴 專注力

【TED-Ed】壓力並非壞事?告訴你壓力如何影響我們的大腦 (How stress affects your brain - Madhumita Murgia)

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    SylviaQQ 發佈於 2020 年 04 月 26 日