Tag Archives: fight or flight

Amygdala: The powerhouse of emotions

Our brain is a palace of structures. It dictates everything we do, how we think, how we behave and how we feel. In this article, we will focus only on the amygdala (sounds like a character out of a Star Wars movie): From what it is, functions, neurophysiological aspects of the amygdala, what happens if it gets damaged, and its relationship with other brain areas.  

Amygdala

What is the amygdala?

The amygdala is a structure in the limbic system that is involved directly with motivation: Particularly related to survival and our emotions. It is also responsible for processing emotions such as fear, pleasure, and anger.

The amygdala is the house where all of our emotions are stored. One of its main functions is to help us to recognize potential threats when we encounter them. When doing this, it revs the body up in preparation for a fight or flight response by increasing our breathing and heart rates. It is also responsible for evaluating the emotional intensity of various situations. This is especially important because since we encounter certain situations repeatedly, from emotional memory, our amygdala wouldn’t need to fire up… unless our brains say otherwise.

The word ‘amygdala’ was derived from the Greek word for “almond” since this part of our brain is shaped like one. Like most other structures in our brain and in other animals, we have two amygdalae. Each amygdala is located on each of the left and right temporal lobe. Since it’s in very close proximity to the hippocampus, the amygdala is involved with the influence of memory consolidation. Memory consolidation is the process that stabilizes a memory trace right when it has been obtained.

Amygdala: The limbic system

To understand the amygdala a little bit better, this article is going to give a swift review of the limbic system and why it’s important.

The limbic system is not a separate system, but a system composed of several key structures in the brain including the diencephalon, mesencephalon, and telencephalon. The limbic system specifically includes the amygdala, thalamus, hippocampus, hypothalamus, basal ganglia, and cingulate gyrus.

You can find the limbic system nuzzled immediately underneath the cerebrum. The limbic system is important because it is responsible for the formation of memories, and our emotional lives are stored in this area of the brain. The components of the limbic system regulate endocrine and autonomic function in response to any sort of emotional stimuli. In short, the three key functions it is known to deal with are arousal (stimulation), memory, and emotions.

Hemispherical differences

Since we possess two amygdalae, it has been noted that the left and right amygdala serve a different purpose in how we process our emotions. Even though the left and right amygdala have independent memory systems, they still work as a team to encode, store and interpret our emotions.

Studies have reported that electrical stimulations to the right amygdala provoke negative emotions of sadness and fear. When looking at the left side, electrical stimulations induce unpleasant (anxiety, sadness, and fear) feelings, yet also has the ability to induce positive emotions such as happiness.

The right hemisphere is commonly associated with declarative memory. Declarative memory stores various information and facts from previously experienced events which need to be consciously recalled. The right amygdala is also responsible for the retention of episodic memory. Episodic memory stores the autobiographical memory, which allows you to recall sensory and emotional experiences of a particular event.

Development of the amygdala

The development of the amygdalae is an interesting tale that consists of developmental differences between the right and left amygdala, as well as sex differences.

When looking at this area of the brain, there are some observable differences in the growth of the amygdalae. The left is the first to develop, reaching its peak 1.5-2 years before the right. Looking aside from the early growth of the left, the right has a continuous increase in volume for a longer period of time. The right side of the amygdala is often associated with face recognition and fear stimuli. As for the left, it is said that its early development provides infants with the capability of being able to detect danger.

There are also considerable differences in the development of the amygdalae between male and females. In the early stages of development of the brain, it is seen that the limbic system in females grows much more quickly than in males. For males, the structural development of the amygdalae occurs over a longer period of time, while females reach their full growth potential 1.5 years before their counterparts. It is noted that reasoning behind the slower development of the male amygdalae is due to relatively larger sizing.

Sex distinction

In regards to the differences in sexes, this area of the brain is one of the best understood. As briefly described above, we see that the amygdala is larger in male adults and in adult rats.

Adding to size, the functioning of the amygdalae differs in males and females. In one study, participants amygdala activation was looked at by watching a horror movie. Results of this study showed a completely different lateralization in the amygdalae between males and females. They showed that enhanced memory of the film was related to more activity occurring in the left amygdala and not the right. For males, it showed that the memory of the film was related to the right and not the left.

The left is responsible for the recollection of details, which results in more thought than action in response to emotionally stressful stimuli. This can be used to attribute why we see less of a physical response in women than in men. The right has been linked to taking action and has been linked to negative emotions. In this scenario, this is why we see males respond to emotionally stressful stimuli in a physical manner.

Functions of the amygdala

  • Memory – This area of our brain has been linked to the storage of our emotional memory. The amygdala is heavily involved in calculating the emotional significance of events that occur in our lives. Since the amygdala has connections to other regions of the brain, it also has an influence on emotional perception. What this means, is that the amygdala alerts us to notice significant events even when we are not paying attention.
  • Arousal – Sexual desire is largely mediated by the limbic system. Activation of our amygdala can cause sexual feelings, memories of sexual intercourse, penile erections, orgasms, uterine contractions, and ovulation.
  • Hormonal secretions  When experiencing stressful events, our amygdala sounds the alarm by sending a distress signal to our hypothalamus. When this happens, the hypothalamus activates the SNS (sympathetic nervous system) by sending signals through autonomic nerves to the adrenal glands. Then, the glands will respond by pumping out epinephrine, also known as adrenaline. The amygdala is also strongly modulated by serotonin, norepinephrine, epinephrine, and dopamine.

What happens if the amygdala is damaged?

Because there are two amygdalae, if there is a bilateral lesion, there is a reduction in aggression and fear. This may mean you may adopt a superman complex and feel like nothing can hurt you or scare you… unless it’s kryptonite. A study was done on monkeys who had bilateral lesions of their amygdala and researchers reported a huge drop in fear and aggression, just as we see in our human counterparts.

Don’t hold your breath there though. Even though the monkeys showed a significant drop in fear and aggression, humans are faced with a lot more when the amygdala is destroyed. A bilateral lesion can cause an individual to have an impaired ability to interpret emotional facial expression. Kind of sounds like Autism. This type of lesion has actually been linked to autism, with MRI scans detecting an increase in amygdala volume.

Neuropsychological correlates of the amygdala

Advancements in neuroimaging technology have made it possible for neuroscientists to make significant findings related it. Data has shown that the size of an individual’s amygdala can be linked to anxiety, and how size may fluctuate due to antidepressant medication consumption (left). Certain studies have also shown children with anxiety tend to have smaller amygdalae.

Aside from those two interesting facts, data has shown that the amygdala plays a large role in particular mental disorders as well as other mental states.

Fear

A very rare genetic disease known as Urbach-Wiethe disease is responsible for focal bilateral lesions of the amygdala in people. Such a disease results in individual’s showing no signs of fear. This finding of the disease continues to prove that the amygdala plays a large role in triggering the state of fear.

Aggression

Several studies that have looked at animals have repeatedly shown that stimulating the amygdala induces sexual and aggressive behavior. 

Schizophrenia 

Schizophrenic patients are known to have enlarged ventricles, as well as enlarged amygdalae.

Social interaction

It has been said that there is a positive correlation between amygdala volume and the size and complexity of social networks. Size, in this case, means the number of contacts an individual may have, while complexity stands for the number of different groups an individual belongs to.

Data reveals that the larger a person’s amygdalae are the larger amount of social networks an individual has.

It has also been shown that the amygdalae are responsible for processing the violations of personal space. It has been observed in fMRI scans that this region of our brain is activated when it is sensed that a person is standing very close to them. For example, the person who is being scanned is aware when the observer is physically close to them, then when the observer is standing at a distance.

Sexual orientation

In recent studies, it has been suggested that there may be possible correlations between connection patterns in the amygdala, and sexual orientation. It has been reported that homosexual males have a tendency to show more feminine patterns in the amygdala than heterosexual males do. Homosexual females tended to show more masculine patterns in the amygdala than heterosexual females.

Bipolar Disorder

It is well documented that in bipolar disorder, there is great amygdala dysfunction during facial emotion processing. Those who have bipolar disorder have also displayed increased activity in their amygdala.

Post-Traumatic Stress Disorder (PTSD)

Patients who suffer from PTSD typically have a hyperactive amygdala in response to various stimuli that are in some way connected to trauma.

Depression

It is also overactive in those who suffer from depression, especially when you present them with sad stimuli. However, when presented with “happy” stimuli, their amygdala is under-active.

Anxiety

It is responsible for setting off a chain reaction for this disorder. It begins to react because some environmental stressor has convinced this area of the brain that you are in danger. However, this is only an issue to worry about when the amygdala is regularly triggered.

Amygdala and other brain regions

It holds some very special connections with other areas of the brain. It is known to make reciprocal connections with the hypothalamus, thalamus, septal nuclei, hippocampus, parahippocampal gyrus, orbital frontal cortex, the brain stem, and the cingulate gyrus.

The amygdala receives input from all senses as well as visceral inputs. Visceral inputs derive from the hypothalamus, parabrachial nucleus, septal area, and orbital cortex. Visual, auditory, and somatosensory information comes through via the temporal and anterior cingulate cortices. Olfactory sensory information is received from the olfactory bulb.

Some output pathways of the amygdala include:

  1. Stria terminals
  2. Ventral amygdalofugal pathway
  3. Directly to the hippocampus
  4. Directly to the dorsomedial nucleus of the thalamus
  5. Directly to the entorhinal cortex

Amygdala/emotional hijacking 

Emotional hijacking is an event that occurs when an individual’s cognitions are overpowered by their emotions. You normally see emotional hijacking occur in the context of fear and aggression. A perfect example of emotional hijacking to kick off this section is when Mike Tyson bit Evander Holyfield’s ear. According to Daniel Goleman who coined the term amygdala hijacking, this bad decision on Tyson’s behalf is the perfect example of it.

The neocortex – the “thinking” brain, has been completely overridden, and the amygdala fires up taking over total control of the brain; Thus the name “amygdala hijacking.” Hijacking can cause a person to perform irrationally, making decisions that are destructive. Not only does this take a toll on an individual (people who experience emotional hijacking are very remorseful after they realize and reflect on what they have done), their social relationships also take a huge hit. Emotional hijacking can lead to verbal or physical attacks, and such a surge of rage can easily cause an individual to severely harm a person, giving them the capacity to kill.

Something to keep in mind is that emotional hijacking is a phenomenon that requires build up. Troubling past experiences that are crippling an individual can be the direct link to why someone will have an outburst like this. When a person has an outburst, they don’t last long, but the consequences can be quite damaging as a result.

However, there is no need to worry. Not all emotional hijacks are distressing. Goleman states that there are positive hijacks. He gives an example that if a joke strikes a person as funny, and their laughter is explosive, that is a limbic response.

There are three signs you can look out for if you happen to experience an emotional hijack:

  • Strong emotional reaction
  • Sudden onset
  • Post-episode realization if the reaction was appropriate or not/regret

Areas of the brain are especially fascinating, especially when looking at them in more depth. Learning about them gives us an idea of what’s going on within ourselves, and we are able to give a reason for our behavior.

Is this your favorite part of the brain after reading the article? Do you have a favorite area of the brain? Please let us know in the comments below! We hoped you enjoyed this article. 🙂

Understanding Your Brain and Stress: What Happens When We’re Stressed?

It’s time to talk about our good ol’ buddy stress. For most of us, it seems to cling to us all day every day, no matter how many times you try to part ways. It’s just become a part of us, so much so that we might feel weird or empty without it. But what is stress? What exactly does stress do to our bodies, to our brains? Why is it such a good thing to have sometimes, but other times seems to overwhelm us? It’s time that we learn more about the delicate relationship between our brain and stress.

Understand your brain and stress

Check your understanding

How much do you know about stress? Take this short quiz to find out!

1. Stress is inevitable.
  • These days, it may seem like we can't avoid stress. Often times, what you think is stressful now you probably won't think is stressful in the future. Try looking at the things that stress you out in a different perspective, or look for ways to make your life easier!
2. People can choose whether or not to be stressed.
  • As you'll learn in this article, stress isn't a switch you turn on and off. Stressful situations spark many complex reactions within your body and cause physiological changes so that you're equipped to handle the stress. While we can manage it, we can't choose whether or not to be stressed.
3. Exercise is a good stress reliever
  • While it may be hard to fit it into tight schedules, exercise is great to relieve stress! It releases feel-good chemicals called endorphins, and lifts your mood for the day. And even better, it clears your mind so you can be more focused and productive in the workplace.
4. Stress is a good for when you need to be motivated
  • When talking about reaching deadlines or a set goal, some stimulating stress can be good for you. It may provide you with enough to get though the day, or to be a little more productive. But pay attention to how you feel- frustration, irritability, and anger can be signs that you're experiencing too much stress.
5. We'd all be bored without stress
  • Stress has become such a big part of our lives that we might feel empty without it- but we don't have to! Think about all the things you could take time to enjoy without the stress of all your responsibilities. It's very possible to do, so start looking for ways you can de-stress!

The biological mechanisms of stress

When we experience a stressor, it sets off reactions in our body to help prepare us to handle it. For example, let’s say you’re camping in the woods for the weekend, and you’re just about head to the tent for the night. All of a sudden, you hear a loud crash, and you turn around to find a huge bear looking through your stuff!

Seeing the bear stimulates your hypothalamus to release two hormones, called corticotrophin-releasing hormone (CRH) and arginine-vassopressin (AVP)CRH travels down to the anterior pituitary and stimulates the release of corticotrophin into the blood stream. Once corticotrophin reaches the adrenal cortex (a gland on top of the kidneys), the adrenal cortex increases the production of cortisol and other hormones called catecholamines. 

Surely this must sound very complicated, but here’s the basic idea. Seeing the bear stimulates the Hypothalamic-Pituitary-Adrenal (HPA) axis, which eventually causes the production of the stress hormone known as cortisol. This hormone causes many changes in our body so that we can properly deal with our stressor.

Your body and stress

AVP rushes to the kidneys and tells it to make less urine and bring more water back into the body. It also sends signals to our blood vessels to constrict, which raises our blood pressure and allows the oxygenated blood to go where its needed. Cortisol limits the amount of insulin production so that less glucose is stored. It then sends all the glucose it can to the rest of the body, so that it has immediate energy when it goes into the “fight or flight” response. Finally, catecholamines such as epinephrine (adrenaline) work with cortisol to get the heart pumping more blood, faster.

Different types of stress can have different impacts on our body. When stress is prolonged, it can have detrimental effects. Here are just a few:

  • Cortisol suppresses the immune system, so the longer cortisol stays in your system, the more at risk you are of getting colds, infections, cancer, food allergies and gastrointestinal issues.

  • The longer your blood vessels are constricted and your blood pressure is elevated, the more at risk you are for vessel damage and plaque buildup. In other words, you’re much more likely to have a heart attack the more you’re stressed.

  • Cortisol can cause weight gain in many ways. One way is because of the high levels of glucose in the blood and the low levels of insulin. This means other cells that need the glucose can’t get it, so they send signals to your brain to tell you you’re hungry. As a result, you overeat, and the unused glucose is stored as fat.

Your brain and stress

Stress can change neural networks

Prolonged periods of stress can cause increased branching in the amygdala– the fear center of the brain. This means that small, less stressful situations can cause huge rises in cortisol levels. Conversely, the hippocampus– which is responsible for learning, memory, and controlling stress- deteriorates and weakens our ability to control our stress.

Stress can shrink your brain

Studies with rat brains have shown that stress can also cause your brain to shrink. Fewer connections between neurons in the prefrontal cortex inhibit our ability to make decisions and judgments. And because the hippocampus deteriorates with prolonged stress, it can make it harder to learn and remember things.

Stress can be detrimental to mental health

Serious mental health problems can arise from stress because of the chemical imbalances cortisol can cause. Because cortisol can make us feel tired after a while, large amounts can have us feeling low in energy or depressed. In other cases, stress activation can lead to severe feelings of anxiety. In many cases, it can actually influence our personality, causing us to be more irritable, hostile, angry or frustrated.

Since stress is such a big part of our daily lives, its more important than ever to take precautions to protect our brain and our body. For tips on how to reduce your stress, click here.

Common Phobias: Living In Fear

Being afraid of things is very common and typical. Fear is a natural response to an immediate threat. It is natural to be afraid of things if they pose you danger and it is natural to worry about something that is going to happen in the future. It happens to everybody and it is something that is very common and typical. However, when does that fear and anxiety turn into phobia? How does one become so terrified of a certain thing that he avoids it at all costs? A phobic will concentrate on that stimuli that brings them fear if it’s present and cannot look away. What keeps them in that vicious cycle? Well, that whole escaping mechanism. Of course, we tend to escape things that scare us but if we do it and then we feel relief for escaping them, then we are actually reinforcing ourselves to be scared of that object or stimuli. If we stick around and see that, actually, there is nothing to be scared of, then we might be able to get rid of the phobia. There are many phobias in the world but there are some that stick out. Common phobias are persistent over time and appear everywhere around the world.

Common Phobias: Living In Fear

Specific phobias divide into different subtypes:

  • Situational subtype: you are afraid of a certain situation, like flying or bridges
  • Blood-injection-injury subtype: you are afraid of any type of injuries or anything that has to do with blood
  • Animal subtype: you are afraid of animals
  • Natural environment subtype: fear of something that occurs in nature like lightening or water.

Specific phobias include an unreasonable, irrational and excessive fear that is triggered by a presence or anticipation of that stimuli that fears them or a specific situation. People will showextreme anxiety when they are presented with the stimulus, in many cases they will have a panic attack, which is why they keep on avoiding the stimulus to the best of their abilities. This avoidance behavior, many times, causes impairment in their daily functioning and daily activities.

Common Phobias: Living In Fear

Common phobias include:

  • Agoraphobia: fear of crowds or leaving home or a safe place. People are scared to be in a place where they cannot escape and often experience panic attacks when they find themselves stuck in a crowd.
  • Acrophobia: fear of heights. A very common one. People tend to avoid tall buildings, balconies bridges and anything else that brings forward their fear.
  • Arachnophobia: fear of spiders. Falls within the animal subtype. This phobia has gender differences and women are more likely to have it than men.
  • Cynophobia: fear of dogs. A lot of times brought on by a traumatic experience involving a dog.
  • Mysophobia: fear of contamination. Germs and dirt make people anxious and fearful. This phobia is closely related to Obsessive-Compulsive Disorder.
  • Ophidiophobia: fear of snakes
  • Pteromerhanophobia: fear of flying. Very common but very easily treated with exposure therapy using systematic desensitization and gradual exposure to flying objects and in the end, flying itself.
  • Trypanophobia: fear of injections
  • Astraphobia: fear of thunder and lightning.
  • SOCIAL PHOBIA: one of the biggest and most common phobias in the world. People fear social situations and they avoid places and situations where the anxiety attack will be triggered. Social anxiety disorder (social phobias) involve being afraid of feeling inadequate, embarrassed and humiliated. Social phobias themselves divide into three categories.
    • Interaction phobias: mixing with others
    • Performance phobias: public speaking or eating with others
    • Generalized phobias: any type of situations that involve people

Common Phobias: Living In Fear