How Does Amygdala Function in Human Brain?

Diego Maradona, one of the influential Argentine soccer players, was put under the care of Paramedics when he collapsed in his chair after Argentina won against Nigeria at the 2018 World Cup.

Maradona was seen overreacting to Argentina’s victory and as a result collapsed while celebrating Argentina’s late victory over Argentina.

Advanced Psychology

Moments like these are common when it comes to human life. Think about the situations when you almost fainted celebrating your success, much like Maradona. Or ponder over the times when you last bursted out on your sibling, a response that you later felt was unjustified and hence not needed.

Day To Day Emotional Attacks

Take for instance Harper’s case. Harper had been preparing for her entrance exam from past one year. On the morning of the exam day, when Harper was getting ready, she had a fight with one of her siblings early in the morning. This got her overwhelmed and put her in a bad mood.

She carried this foul mood to the examination hall where she found herself not able to focus on her exam. As a result, her brain was engulfed with panic and she could not attempt majority of the given questions.

Thus, when she came out of the exam hall, she knew that she had ruined her one year’s effort. This got authenticated when results were declared as she could barely pass.

Impassioned moments like these put you in a state where you simply jump to actions even before your thinking brain gets a chance to understand the situation at hand.

All these emotional explosions are a result of a centre in our limbic brain known as the ‘Amygdala’.

It is the Amygdala that results in both distressing as well as extremely pleasant emotions that can barely be controlled.

In this article, you will learn, what is Amygdala, how does Amygdala function and role of other limbic structures in stimulating emotions in humans.

What is Amygdala?

Amygdala is an almond shaped collection of interconnected structures, located right above the brainstem. Furthermore, each side of the brain has one amygdala each.

In other words, there are two amygdalas, one located at each side of the head close to the temporal lobe. As compared to primates, the human amygdala is comparatively large in size.

Further, Amygdala along with nearby Hippocampus form the two important parts of the Limbic Brain. In fact, these are the primitive Limbic structures that lead to the development of Cortex and Neocortex in human brain.

Thus, much like the primitive times, most of memorizing and learning takes place inside these limbic structures.

The Amygdala, on the one hand, specializes in emotional issues and is a storehouse of emotional memories. On the other hand, Hippocampus is the Limbic structure that acts as a storehouse of factual information that is necessary for giving emotional meaning to the given set of experiences or events.

Example

Take for instance Harpers case given above. Now, the Amygdala will be responsible for sending signals of anxiety the next time Harper would sit for the exam. Whereas, the Hippocampus would help her memorize the other details of the incident such as the location of the examination hall, its setup, her peers who took the exam, etc.

Thus, given the Amygdala’s role in the emotional brain, studies have shown that if the amygdala is removed or severed from the rest of the brain, there would be no emotions in human life.

As mentioned in Daniel Goleman’s Emotional Intelligence book, Joseph LeDoux was the first neuroscientist who discovered the important role played by Amygdala in the emotional brain.

LeDoux’s research reveals that Amygdala can take charge of what human beings do while the thinking brain, the neocortex, is still at work to understand what the existing event is all about.

Amygdala Function

In order to understand how Amygdala functions, we will take into consideration one of the emotions that is crucial for the survival of human beings. This emotion is none other than fear.

In primitive times, the very survival of our ancestors was due to the emotion Fear whenever their life was endangered due to the attack of wild animals or interlopers. In events like these, humans had to make quick decisions of either escaping or fighting back.

This required them to respond instantaneously as waiting for long would mean putting their life in danger. So, fear played a great role here as it enabled them to react quickly by either escaping, fighting or killing the attacker.

Now, Fear undoubtedly played a key role in the survival of our ancestors. But in modern times, these misguided fears have lead to a variety of challenges such as panic attacks, anxiety, worry, phobias and obsessive compulsive disorders.

Given this, it would be interesting to know what exactly happens when humans are in the grip of such emotions? Well, the point of origin of such emotional explosions is the Amygdala. Let’s understand how does Amygdala gets triggered leading to Amygdala Hijack.

Example

Let’s put Harper in another situation. She is asked to prepare a presentation which she would have to deliver in a class of seventy students. Since the topic given to her for the presentation is not of her interest, she starts to think that she will not be able to do well.

The very thought of standing and speaking on that topic gives her jitters. Even after hours of practice in her hostel room, she is not able to get out of the thought of screwing the presentation up.

On the day of presentation, the thought overpowers her brain as she goes all blank. Even after repetitive cheering from the audience, she is unable to pull off the presentation. On asking her later what happened to her, she explains that she got overwhelmed by the thought that she would have to present in front of people who are strangers.

Let’s see what went wrong in Harper’s brain that made her go all blank.

Role of Amygdala

  • Taking in Sensory Input

The first step involves the brain taking input from the physical world and converting it into neural signals understood by the brain so as to make it alert. In Harper’s case, this input was a crowd of 70 strangers that she saw the moment it was her turn to give the presentation.

Thus, this input takes enters the brain via eyes, goes to the brainstem and then further to the Thalamus. Form Thalamus, this information gets separated into two branches.

A small amount of neural signals go directly to the Amygdala and the Hippocampus. Whereas, the majority of these input signals go to the visual cortex in the Occipital Lobe. Here the information gets assessed and analyzed.

  • Sorting By Hippocampus

As mentioned above, Hippocampus is a Limbic structure that memorizes the factual information about events and occurrences. Thus, the moment sensory information reaches Hippocampus, it compares the input with the facts of similar events already registered to see if the event at hand is familiar.

  • Higher Level Analysis By Visual Cortex

While the information gets sorted for familiarity in Hippocampus, amount of sensory input reaching the Visual Cortex goes in for undertaking higher level analysis of the sensory input so received.

In Harper’s Case, the visual cortex would try to understand the scene witnessed by her, that is, the panel of judges, the performance of the co-presenters, the reaction of the crowd etc.

Now, the visual cortex will present its understanding such as expert judges, outstanding performance by the co-presenters, demanding crowd and send these messages to the Amygdala and the Hippocampus.

Now, Amygdala and Hippocampus would further compare this analysis to the stored memories. If the decision given by both the Amygdala and the Hippocampus is encouraging, then the general state of vigilance does not move to the next level.

Encouraging decision here means that the verdict given by both Amygdala and Hippocampus is say supporting crowd, familiar guests and judges, fair performance by co-presenters etc.

However, if both Amygdala and Hippocampus are not certain about the sensory inputs received, another set of interaction between amygdala, hippocampus and the prefrontal cortex takes place. This escalates the uncertainty further making the person more alert and worried about the underlying worry or fear. In harper’s case, the fear relates to facing people, her performance in respect of presentation etc.

If this analysis by amygdala, hip[pocampus and the prefrontal cortex does not get any answer, the amygdala gets triggered. It sends alert signals that further activate hypothalamus, brainstem and the autonomic nervous system.

Parts of Amygdala

Let’s understand how the Hypothalamus, Brainstem and the ANS get activated by the alarming signals received by the Amygdala.

Amygdala is divided into various sections, each receiving different kind of information. Following are the various parts of Amygdala and its functions:

  • Lateral Nucleus

Receives signals from Thalamus, auditory and visual cortexes.

  • Corticomedial Nucleus

Receives information of smell via olfactory bulb. The received information goes to the Hypothalamus.

  • Central Nucleus

Messages of taste and signals from the internal organs go to the central area of the Amygdala. The information received both by the central and the medial nucleus goes to the Hypothalamus. This leads to secretion of Corticotropin Releasing hormone (CRH) which puts the body in flight or fight mode through a series of other hormones released by various glands.

Further, through Central Nucleus, signals are sent to the ANS through Medulla. This further stimulates the cardiovascular system, muscles and the gut.

  • Basal Nucleus

Information from the basal nucleus goes to Corpus Striatum that is responsible for bringing movement in the body.

From the basolateral area, the information goes to Cingulate Cortex and the central gray fibers of the brain. In humans, these signals are responsible for high-pitched voice when encountered with a threat.

In addition to this, Amygdala sends signals to an area in the Brainstem called Locus Coeruleus. This part is responsible for producing and distributing a Hormone called Nor-Adrenaline (Norepinephrine). This hormone is responsible for further stimulating the areas of the brain that receive this hormone, thus making them even more sensitive.

In other words, Norepinephrine spreads throughout cortex, brainstem and the limbic system which leads to the hijacking of brain. As a result, even an ordinary situation like a presentation seems extraordinary to the brain sending the sensations of fear through the human body.

Conclusion

Thus, it is the Amygdala that is the source of all emotions in humans. Fear, anger, anxiety, happiness, love, etc all originate from Amygdala which if extremely intense lead to emotional hijacking. As a result, emotion overpowers rational brain making human react in an unpleasant which they later regret.

Advanced Psychology