• Question: what part of the brain is most active when anyone is under stress or pressure? why?

    Asked by khizarsiqbal to Faye on 22 May 2012.
    • Photo: Faye Didymus

      Faye Didymus answered on 22 May 2012:

      Hi khizarsiqbal, that’s such a good question! As scientists, we’re making great progress towards understanding the brain but unfortunately we still know very little about they when’s and why’s of how the brain works. There is some really interesting scientific research though that takes pictures (scans) of the brains and can see which areas are most active during different tasks. This has helped us to understand what part of the brain is active when we’re stressed. Whilst we’re a long way from fully understanding stress and the brain, this is what we do know….

      We think that the primary area of the brain that deals with stress is the limbic system – it is located deep inside the brain in the cerebral cortex, just above the brainstem. Because of its influence on emotions and memory, the limbic system is often referred to as the emotional brain (also called the mammalian brain). Whenever you perceive a threat (think that there is some sort of danger, stress, or pressure), imminent or imagined, your limbic system immediately responds via your autonomic nervous system – the complex network of endocrine glands that regulates metabolism. Your sympathetic nervous system does an excellent job of rapidly preparing you to deal with what is perceived as a threat to your safety. Its hormones initiate several metabolic processes that best allow you to cope with sudden danger. Your adrenal glands release adrenaline (also known as epinephrine) and other hormones that increase breathing, heart rate, and blood pressure. This quickly moves oxygen-rich blood to the brain and to the muscles needed for fighting or fleeing – linked to the “fight or flight response” that you may have heard of. You have plenty of energy to do either because adrenaline causes a rapid release of glucose and fatty acids into your bloodstream. Also, your senses become keener, your memory sharper, and you are less sensitive to pain. And all of this is because we have evaluated something in our environment as stressful!

      Other hormones shut down functions unnecessary during the emergency. Growth, reproduction, and the immune system for example all go on hold. Blood flow to the skin is reduced. That’s why chronic stress leads to sexual dysfunction, increases your chances of getting sick, and often manifests as skin ailments. With your mind and body in this temporary state of metabolic overdrive, you are now prepared to respond to a life-threatening or stressful situation.

      After a perceived danger has passed, your body then tries to return to normal (known as homeostasis). But this may not be so easy, and becomes even more difficult with age. Although the hyperactivating sympathetic nervous system jumps into action immediately, it is slow to shut down and allow the tranquilizing parasympathetic nervous system to calm things down. Once your stress response has been activated, the system wisely keeps you in a state of readiness. All of this sounds pretty dramatic if we consider a small stress or pressure but bear in mind that an appropriate stress response is a healthy and necessary part of life. One of the things it does is to release norepinephrine, one of the principal excitatory neurotransmitters. Norepinephrine is needed to create new memories. It improves mood. Problems feel more like challenges, which encourages creative thinking that stimulates your brain to grow new connections within itself. Stress management is the key, not stress elimination. The challenge in this day and age is to not let the sympathetic nervous system stay chronically aroused so we try to manage stress so that we can relax when we need to.

      Don’t worry about all of the big words in the above – depending on what stage of your studies you’re at, I doubt you’ll need to know all of them but I thought I’d put the technical terms in in case you’re interested. I’m sure you will understand the important messages…any questions, just give me a shout!