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What Part Of The Brain Controls Stress

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Effects Of Stress On The Body

How Stress Affects the Brain

Chronic stress doesnt just lead to impaired cognitive function. It can also lead to other significant problems, such as increased risk of heart disease, high blood pressure and diabetes. Other systems of the body stop working properly too, including the digestive, excretory and reproductive structures. Toxic stress can impair the bodys immune system and exacerbate any already existing illnesses.

E Socioeconomic Status And Health

Differences in income and education, collectively referred to as socioeconomic status have significant effects on mortality and morbidity for a number of diseases, with low SES faring worse than middle SES and much worse than high SES individuals in industrialized western societies . The SES differences are also evident, in a linear fashion from low to high SES, for predisease conditions such as obesity and metabolic syndrome and fibrinogen , as well as substance abuse and anxiety and mood disorders . Subjective SES, that is, where people rate themselves on a scale of income and education, is also an effective predictor of health status . Possible mediators of the subjective SES-health link include negative affect over such issues as economic insecurity associated with low SES and sense of control related to socioeconomic position , as well as low self-esteem.

What Are The Parts Of The Brain

The brain is made up of three main sections: the forebrain, the midbrain, and the hindbrain.

The Forebrain

The forebrain is the largest and most complex part of the brain. It consists of the cerebrum the area with all the folds and grooves typically seen in pictures of the brain as well as some other structures under it.

The cerebrum contains the information that essentially makes us who we are: our intelligence, memory, personality, emotion, speech, and ability to feel and move. Specific areas of the cerebrum are in charge of processing these different types of information. These are called lobes, and there are four of them: the frontal, parietal, temporal, and occipital lobes.

The cerebrum has right and left halves, called hemispheres. They’re connected in the middle by a band of nerve fibers that lets them communicate. These halves may look like mirror images of each other, but many scientists believe they have different functions:

  • The left side is considered the logical, analytical, objective side.
  • The right side is thought to be more intuitive, creative, and subjective.

So when you’re balancing your checkbook, you’re using the left side. When you’re listening to music, you’re using the right side. It’s believed that some people are more “right-brained” or “left-brained” while others are more “whole-brained,” meaning they use both halves of their brain to the same degree.

In the inner part of the forebrain sits the thalamus, hypothalamus, and :

The Midbrain

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Human Neuroimaging Studies Of The Hippocampus

Complementing animal studies of stress-related processes mediated by and affecting neuroplasticity in the hippocampus, a growing number of human structural neuroimaging studies have begun to examine stress processes in association with aspects of gross hippocampal morphology. For example, individuals with stress-related psychiatric disorders, such as major depressive disorder and post-traumatic stress disorder, show volumetric reductions in the hippocampus.â Reduced hippocampal volume has also been found in Cushing’s Disease. Interestingly, in Cushing’s, surgical correction of hypercortisolemia has been reported to at least partially reverse hippocampal volume reduction as well as mood and memory deficits., In depression, there is evidence of volumetric increase in the hippocampus after antidepressant treatment, suggesting that the deficits in depression are potentially reversible. Moreover, there is increasing support for the notion that targeting the plasticity of the hippocampus in depression and mood disorders may underpin pharmacological and nonpharmacological treatment efficacy.

Physiological Effects Of Stress On The Brain

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Stress is a chain reaction. When someone experiences a stressful event, the amygdala, an area of the brain that contributes to emotional processing, sends a distress signal to the hypothalamus, Harvard Health Publications of Harvard Medical School explains. This area of the brain functions like a command center, communicating with the rest of the body through the nervous system so that the person has the energy to fight or flee.

This fight-or-flight response is responsible for the outward physical reactions most people associate with stress including increased heart rate, heightened senses, a deeper intake of oxygen and the rush of adrenaline. Finally, a hormone called cortisol is released, which helps to restore the energy lost in the response. When the stressful event is over, cortisol levels fall and the body returns to stasis.

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Traumatic Stress Effects And Paradoxical Actions Of Glucocorticoids

Another paradoxical effect of a mediator of stress and adaptation to stressors involves glucocorticoid actions in relation to acute vs chronic stress effects upon the amygdala. Consistent with the elevation of corticosterone after acute and chronic stress accompanying the increase of dendritic length in BLA, as noted above , a single large bolus of corticosterone mimics the ability of 10 consecutive days of CIS to increase anxiety and dendritic length in BLA . Furthermore, a single traumatic stressor causes a naïve rat to develop anxiety and increased spine density on BLA neurons, but with no increase in BLA dendritic length, with a delay of 10 days as noted above .

But a timed elevation of a low to moderate dose of corticosterone at the time of the traumatic stressor prevents the increased anxiety and increased BLA spine density 10 days later . A similar protective effect of corticosterone has been reported for a different acute traumatic stress paradigm . One possibility currently under investigation is that corticosterone stimulation of endocannabinoid production may be involved , as endocannabinoids have an important role in the amygdala regulating basal and chronic stress levels of HPA activity and endocannabinoids are known to modulate amygdala dendritic structure .

Mood Cognition And Behaviour

It is well established that chronic stress can lead to depression, which is a leading cause of disability worldwide. It is also a recurrent condition people who have experienced depression are at risk for future bouts of depression, particularly under stress.

There are many reasons for this, and they can be linked to changes in the brain. The reduced hippocampus that a persistent exposure to stress hormones and ongoing inflammation can cause is more commonly seen in depressed patients than in healthy people.

Chronic stress ultimately also changes the chemicals in the brain which modulate cognition and mood, including serotonin. Serotonin is important for mood regulation and wellbeing. In fact, selective serotonin reuptake inhibitors are used to restore the functional activity of serotonin in the brain in people with depression.

Sleep and circadian rhythm disruption is a common feature in many psychiatric disorders, including depression and anxiety. Stress hormones, such as cortisol, play a key modulatory role in sleep. Elevated cortisol levels can therefore interfere with our sleep. The restoration of sleep patterns and circadian rhythms may therefore provide a treatment approach for these conditions.

Depression can have huge consequences. Our own work has demonstrated that depression impairs cognition in both non-emotional domains, such as planning and problem-solving, and emotional and social areas, such as creating attentional bias to negative information.

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What Other Factors Does The Brain Take To Make A Decision

With each decision we create our life, since we are the sum of what we have decided. Developing the ability to make resolutions is crucial to shape the life we want since decisions are the engine that move our actions and influence the present and help create the future.

However, it is not always easy to decide. Sometimes we do it automatically and almost without realizing it, but there are other situations that paralyze us and we get stuck without knowing what to do. And it is precisely this disability that conditions conflicts in social, personal and work life.

Making a decision is taking a loss and nobody likes to lose. Deciding is ruling out, and in choosing one way to proceed we are omitting all the others. For this reason, action is often postponed.

What Influences Our Capacity For Coping With Stress

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Several factors influence our capacity for coping with stress:

  • The presence of a social network
  • Our skill and confidence in assessing a complex situation and then developing and evaluating solutions
  • Personal variables such as physical health, experience, confidence, anxiety threshold and problem-solving abilities .

Stressful events are a universal part of the human experience. You may or may not be able to change your current situation, but you can take steps to manage the impact these events have on you.

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What Are The Symptoms Of An Amygdala Hijack

The symptoms of an amygdala hijack are caused by the bodys chemical response to stress. When you experience stress, your brain releases two kinds of stress hormones: cortisol and adrenaline. Both of these hormones, which are released by the adrenal glands, prepare your body to fight or to flee.

Together, these stress hormones do a number of things to your body in response to stress. They:

  • increase blood flow to muscles, so you have more strength and speed to fight or flee
  • expand your airways so you can take in and use more oxygen
  • increase blood sugar to provide you immediate energy
  • dilate pupils to improve your vision for faster responses

When these hormones are released, you may experience:

An amygdala hijack may lead to inappropriate or irrational behavior. After an amygdala hijack, you may experience other symptoms like embarrassment and regret.

How Does Chronic Stress Physically Change The Brain

Brain size

Chronic, or long-term, stress can affect the size of your brain and even its genetic makeup.

Many of these physical changes happen as a result of high cortisol levels and changes to the way your brain functions under prolonged stress.

For instance, according to 2008 research , long-term exposure to cortisol can shrink the prefrontal cortex, the area of your brain involved with planning and making decisions.

Research from 2016 found higher cortisol levels were directly linked to a lower volume of many parts of the prefrontal cortex.

Stuck on repeat

One theory is that over time, emotional responses to stress become a vicious cycle in the brain.

If your brain keeps activating a stress response in more situations, it may cause the parts of your brain that get more use like the amygdala to strengthen. Other areas that get less use as a result the prefrontal cortex can become smaller with less use.

Smaller capacity for memory and emotional regulation

Long-term stress is also linked to a smaller hippocampus, the part of the brain responsible for emotion processing and memory.

Gene expression

In addition, stress can affect your brains DNA through epigenetics, a process in which your environment interacts with and can suppress or activate family genes.

For example, according to , stress caused by childhood trauma is connected with epigenetic changes to the brains DNA and HPA axis.

These changes then impact your brains and your response to stress.

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Human Studies Of The Prefrontal Cortex

Lower subjective social status, as reflected by a lower self-reported ranking on a âsocial ladderâ, was associated with reduced gray matter volume in the perigenual area of the anterior cingulate cortex . Illustration of 10-point social ladder scale used to assess subjective social status. Overlaid on an anatomical template is a statistical parametric map of color-scaled t-values, which illustrate the pACC area where lower subjective social status was associated with reduced gray matter volume across individuals. Plotted along the y-axis is the standardized gray matter volume values for pACC area profiled in B. Plotted along the x-axis are social ladder rankings from the scale illustrated in A . *P< 0.001. From Gianaros et al. , reprinted with permission.

Blood Supply To The Brain

Your Brain on Stress and Anxiety

Two sets of blood vessels supply blood and oxygen to the brain: the vertebral arteries and the carotid arteries.

The external carotid arteries extend up the sides of your neck, and are where you can feel your pulse when you touch the area with your fingertips. The internal carotid arteries branch into the skull and circulate blood to the front part of the brain.

The vertebral arteries follow the spinal column into the skull, where they join together at the brainstem and form the basilar artery, which supplies blood to the rear portions of the brain.

The circle of Willis, a loop of blood vessels near the bottom of the brain that connects major arteries, circulates blood from the front of the brain to the back and helps the arterial systems communicate with one another.

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Animal Studies Of The Prefrontal Cortex

Chronic stress also causes functional and structural changes in the medial prefrontal cortex, particularly in areas of anterior cingulate, prelimbic, infralimbic, and orbitofrontal regionsâcorresponding to conventional animal anatomical labeling. For example, CRS and chronic immobilization cause dendritic shortening in medial prefrontal cortex,,,â but also produce dendritic growth in orbitofrontal cortex. Taken together with the differential effects of the same stressors on the hippocampus and amygdala, these actions of stress are reminiscent of recent work on experimenter versus self-administered morphine and amphetamine, in which different, and sometimes opposite, effects were seen on dendritic spine density in orbitofrontal cortex, medial prefrontal cortex, and hippocampus CA1. For example, amphetamine self-administration increased spine density on pyramidal neurons in the medial prefrontal cortex and decreases spine density on orbitofrontal pyramidal neurons.

The Difference Between Stress And Anxiety

Weve all heard the terms stress and anxiety used interchangeably. The issue with this is that stress and anxiety are actually different feelings. When you feel stress, its because of a known source youre on a tight deadline or the kids just wont listen. This stress might manifest in feelings of anger, sadness, or irritability, as well.

Anxiety, on the other hand, is a specific feeling of fear and/or dread. It may not have a known trigger either. People with an anxiety disorder will oftentimes wake up feeling anxious for no apparent reason. Anxiety can also stem from chronic stress, as well. Someone whose body has a consistent surge of stress hormones running through it is at a higher risk for developing generalized anxiety.

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The Brain’s Response To Trauma

When your brain identifies some type of threat, the amygdala is responsible for initiating a fast, automatic reaction known as the fight-or-flight response. Think of the amygdala as the alarm that sounds when something poses a danger. This alarm prepares your body to respond, either by dealing with or getting away from the threat.

The amygdala also communicates with other areas of the brain, including the hypothalamus, which then releases the stress hormone cortisol. It is the brain’s prefrontal cortex that must then assess the source of the threat and determine if the body needs to stay on high alert to deal with the threat or if the brain needs to begin calming down the body.

The prefrontal cortex acts as a braking system that helps return your body to a normal state when you realize that the threat doesn’t pose a danger or after the threat has passed.

When people have symptoms of post-traumatic stress disorder, the amygdala becomes hyperactive while the medial prefrontal cortex becomes hypoactive.

In other words, the part of the brain that triggers a fight-or-flight response responds too strongly, often in a way that is disproportionate to the danger posed by the threat. At the same time, the part of the brain responsible for calming this reaction does not work well enough.

D Being Stressed Out: Example Of Sleep Deprivation And Its Consequences

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The common experience of being stressed out has as its core the elevation of some of the key systems that lead to allostatic overload: cortisol, sympathetic activity, and proinflammatory cytokines, with a decline in parasympathetic activity. Nowhere is this better illustrated than for poor or inadequate sleep, which is a frequent result of being stressed out. Sleep deprivation produces an allostatic overload that can have deleterious consequences.

Because the brain is the master regulator of the neuroendocrine, autonomic, and immune systems, as well as behavior , alterations in brain function by chronic stress can, therefore, have direct and indirect effects on the cumulative allostatic overload. Reduced sleep duration has been reported to be associated with increased body mass and obesity in the NHANES study . Sleep restriction to 4 h of sleep per night increases blood pressure, decreases parasympathetic tone, increases evening cortisol and insulin levels, and promotes increased appetite, possibly through the elevation of ghrelin, a proappetitive hormone, along with decreased levels of leptin . Moreover, proinflammatory cytokine levels are increased with sleep deprivation, along with decreased performance in tests of psychomotor vigilance, and this has been reported to result from a modest sleep restriction to 6 h/night .

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Even Superheros Sometimes Need Help

Even though our bodies have these super stressresponse systems, humans are best at dealing with stress when they have a little help. This help is called social support, which refers to the ways that other people can help us feel safe, loved, and cared for . Your friends and family may provide social support by hugging you when you are sad or scared, hanging out with you when you feel lonely, or celebrating with you when you are excited. We especially need social support when we are very young. Remember earlier when we mentioned that the amygdala shares a special connection with the prefrontal cortex? This connection does not mature until you are a teenager therefore, infants and children rely on their parents to help them calm down.

  • Figure 2 – This study compared the brains of children and teenagers while they viewed emotional faces.
  • When looking at negative emotional faces you can see that the childrens amygdala activity was decreased when their mothers were present. This tells us that the moms were buffering stressresponse systems in the children by providing social support. The teenagers amygdala activity increased when they viewed the emotional faces even though their mothers were present.

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