Tag Archives: Exploring your mind

The Neuroanatomy of Emotions: The Limbic System

Exploring Your Mind
March 20th, 2020

In order to describe the neuroanatomy of emotions, Paul Broca first described the limbic system in 1878. It wasn’t until later, in the 1930s, that James Papez finally named it the limbic system, and suggested that it participated in the neural circuit of emotional expression (Kolb and Whishsaw, 2003).

The limbic system corresponds to a functional concept including several neural structures and networks, which play a prominent role in emotional aspects. And since it involves emotional manifestations, it’s also related to motivation. More concretely, it’s related to action, learning, and memory-oriented motivation. In fact, it’s easier to remember or learn something that has a high emotional value (Cardinali, 2005).

The neuroanatomy of emotions: beyond brain structures

Several authors suggest that emotional responses not only involve the nervous system. In fact, experts believe that other systems, such as the immune and endocrine systems, participate in this process. For instance, Damasio (2008) introduced the somatic marker hypothesis, which states that what makes an experience valuable isn’t just cognitive evaluation but a certain somatic state as well.

A somatic state is a result of the activation of complex subcortical neurohumoral circuits that give emotional value and relevance to a certain thought.

The brain and the limbic system.

The limbic system and other command systems

Some important research studies have defined more specific systems than the limbic system. For example, in his studies on affective neurosciences, Jaak Panksepp (2001) conceptualized systems based on primary emotions: sadness, fear, and rage, among others. The main ones are:

Seeking/expectancy system

This system motivates the pursuit of pleasure; it activates a person’s interest in the world. It’s circuits run on dopamine. Furthermore, some neuroscientists believe it’s similar to Freudian libido and lust (Bleichmar, 2001; Solms and Turnbull, 2005).

The expectancy system is part of the mesolimbic/mesocortical system, which operate simultaneously and affect each other, forming the so-called extended amygdala (Cardinali, 2005).

Natural pleasurable stimuli (such as food or sex) and addictive drugs promote dopamine release, which takes place in the ventral tegmental area (VTA) neurons. These send projections to the nucleus accumbens and finally translate into euphoria and behavior reinforcement. When this system is highly stimulated, an individual will seek pleasurable sensations (Leira, 2012).

Rage/anger system

  • Originates due to frustration toward an object, person, or situation.
  • Physical manifestations include “fight” motor programs, such as jaw clenching or yelling.
  • In addition, the activity originates in the amygdala toward the stria terminalis and the hypothalamus.

Fear/anxiety system

  • It mainly involves the amygdala.
  • Responses such as “fight” and “escape” stem from the amygdala’s lateral and central nuclei, which respectively send projections to the medial and anterior part of the hypothalamus.

Panic/sadness system

  • Associated with feelings of loss and sadness.
  • It’s seemingly related to social interactions and bonding and especially with the maternity process and attachment behaviors.
  • Endogenous opioids take part in this system. Separation or loss of something with affective value leads to reduced concentration of the endogenous opioids, which determine a painful experience.
  • Biological foundation. The anterior cingulate gyrus and its projections to the thalamus and hypothalamus toward the ventral tegmental area.
A man having a panic attack.

Inhibition and regulation of the prefrontal cortex emotional responses

The previous command systems need experiences in order to develop. Thus, with voluntary actions, the external world information coming through association areas goes to the prefrontal cortex, which then connects with the motor system. As per involuntary actions in which there are emotional reactions, subcortical areas mediate actions (such as the command systems we mentioned above).

In the neuroanatomy of emotions, the prefrontal cortex regulates emotional responses. It takes place in the ventral medial area, acting as an inhibitor, and in the lateral area. The latter has more of a controlling function of conscious thoughts. It’s the protagonist in the learning, planning, and decision-making processes.

Therefore, childhood experiences will shape the inhibitory system in formation, which also explains the differences in emotional regulation in children and adults.

The Amygdala and Anxiety: What’s the Link?

May 19, 2020

Neuroscientists call the neurological structures that mediate anxiety disorders the “web of fear”. Out of all these areas, the most relevant is the brain’s amygdala: a region as small as a marble.

There’s a direct relationship between the amygdala and anxiety disorders. This is a fact that’s been known for a long time. However, in addition to this fact, there’s another that’s as curious as it is striking. Neuroscientists have discovered that some people have a larger amygdala and that this increases the risk of mood disorders.

Is this perhaps a coincidence? Can one really be born with such a neurological disorder? Research is showing us that, in reality, this peculiarity is due, above all, to a very specific factor. This factor is none other than the suffering caused by a difficult childhood, subject to constant stress, whether due to mistreatment, physical abandonment, or emotional neglect.

In other words, your previous experiences, and how they affected you, model your brain’s architecture. Moreover, it does so in a very unique way: if you suffer stress in childhood, it alters all that neurobiology related to what scientists call the “web of fear”.

Regions such as the amygdala, the hippocampus, or the anterior dorsal cingulate cortex suffer small alterations that will increase the risk of suffering anxiety disorders in adulthood.

An anxious woman.

The amygdala and anxiety: what’s the connection?

We all experience anxiety throughout our lives, with varying degrees of intensity. Stressful situations that you go through, such as facing a job interview, exams, or a conference that you have to speak at, put you through the mill. They create fear, uncertainty, or anxiety about what’s going to happen and whether you’re going to do well.

These experiences, however complex they may seem to you, are completely normal. However, it isn’t normal to suffer constant anxiety.

Sometimes, there’s no specific trigger. You can feel a permanent sense of anxiety that you can’t explain, and that alters your entire reality, both physically and psychologically. This anxiety is pathological and acts like a poison that affects your health and potential.

Psychological conditions such as phobias, post-traumatic stress disorder, and generalized anxiety disorder, can affect you and are linked to anxiety. Because of this, neuroscientists have wondered for decades what actually happens in the human brain and what brain structures cause this anxiety.

The “web of fear” and the amygdala

Anxiety isn’t the result of the activity of just one brain structure. In fact, it’s the result of a complex combination of several areas of the brain. This makes up what scientists refer to as the “web of fear”. The name alone is scary enough, but what is it exactly?

To understand it better, we’ll start by explaining that the human brain is both emotional and rational. It has some very old areas that articulate and dominate the processes that are linked to your sensations, emotions, and feelings. Specifically, the frontal areas of the cerebral cortex control the cognitive and more reflexive processes.

When someone experiences an anxiety disorder, their brain is taken over by fear. We could say that the brain is “hijacked” by a series of structures that limit its more logical and reflective thinking.

Moreover, the part of your brain that orchestrates this control is the amygdala. This fact was discovered in the 90s, thanks to a study conducted at Yale University by Dr. Michael Davies.

  • We know that the amygdala is capable of extracting information about what surrounds us in an ultra-fast way. It detects risks and threats, whether real or imagined.
  • Soon after that, it activates the sensation of fear to get you ready to flee or to defend yourself.
  • After that, this feeling of fear and alertness also reaches the dorsal anterior cingulate cortex (which is located in the frontal lobe). What this structure does is amplify the sensation of fear and block the most rational thoughts. Emotions are now controlling your brain, or, more specifically, anxiety. Your brain is wanting you to react to this situation.
A brain with lights.

Alterations in the amygdala due to a stressful childhood

In 2013, Stanford University made a great discovery. Professor of Psychiatry Dr. Vinod Menon discovered through MRI scans that some people had a larger than average amygdala. These people also had other correlating factors.

The first was that many of them suffered from anxiety disorders. The second was that they had experienced a traumatic or, at least, stressful childhood due to factors such as abandonment or emotional neglect, among others.

Therefore, it seems that having a larger amygdala causes alterations in the connections between other regions of the brain responsible for the perception and regulation of emotions.

This creates hyperactivity, and the cerebral amygdala becomes more sensitive and finds it more difficult to regulate fear, anguish, anxiety, and the feeling of threat, among others. However, Dr. Menon insists on one fact: experiencing a difficult childhood won’t necessarily mean that a person will suffer from mood disorders in adulthood. However, there’s a risk and a greater probability.

Knowing this, science is focusing on regulating the activity of the amygdala. Something like this could give us new and valuable tools to help us treat anxiety, a condition that, as you well know, is very common nowadays.