Endogenous vs. Exogenous

Overview:

Sometimes it is essential to manage a feeling and not respond to that. This is known as emotion regulation. Emotions are filtered by many specific parts of the brain, according to research. There isn’t just one location in the body that is in charge of processing emotions. Several brain areas collaborate as a team. This is why neurobiologists claim that emotions are handled by a brain network, referred to as an emotion-processing network. 

Emotions are experienced by every human being; however, the practice of self-control enables a person to suppress unwanted or undesirable responses to the said experienced feelings. This means that endogenous inhibition of emotions is possible. However, there are external factors that can dictate the expression of a person’s feelings, and those factors are known as exogenous factors. Scientists have worked for many years on the anatomy of the brain to understand the working and processing of emotions inside the brain.

In this article, the emotion-processing centre of the brain is discussed in detail with the function of each structural component highlighted for better understanding. The difference between endogenous and exogenous emotional inhibition has been discussed by sharing findings of different scientific researches.

Summary:

  • The thalamus is the place where signals and responses from the higher parts of the brain are received to be further sent to the cerebellum and the medulla oblongata.
  • The cerebellum has a good influence on emotions and the reactions they can cause, and it also aids in noise and texture discrimination and plays a vital role in learning.
  • The limbic system is the specific region of the brain that regulates feelings and the process of recollection (otherwise known as memory).
  • The limbic system consists of the following structures: Amygdala, hippocampus, and hypothalamus.
  • A distinguishing feature of these feelings and emotions is that voluntary production of these sensations is possible
  • The researchers discovered a neural distinction between endogenous and exogenous emotional inhibition. Exogenous inhibition of negative feelings has been linked to brain activity in the lateral prefrontal cortex, specifically the middle and inferior frontal gyrus, as have previous studies on exogenous inhibition of activity.
  • Exogenous inhibition of negative feelings has been linked to brain activity in the lateral prefrontal cortex, specifically the middle and inferior frontal gyrus, as have previous studies on exogenous inhibition of activity.

The brain and its parts:

Self-control is a necessary component of human creation. It has been interpreted as the capability to change one’s conduct, particularly by superseding impulses in order to align behaviour and attitude with objectives and outcomes. Notably, self-control can also be implemented to emotions, such as when a person tries to overcome the feeling of nervousness during a stage fright or when they try to stay calm when they are offended. 

Besides the practice of self-control, there are numerous other tasks performed by the brain and its parts. Some of them are described below.

Different parts of the brain, located just above the brain stem, are associated with the perception of thoughts and behaviour. The thalamus is in the shape of an oval structure, much like an egg. It is located above the brain stem and it filters more sensory input lining up from the spinal cord and the reticular formation before relaying several of these residual messages to higher levels of the brain. The thalamus is the place where signals and responses from the higher parts of the brain are received to be further sent to the cerebellum and the medulla oblongata. The thalamus is very crucial when it comes to the process of sleeping, as it blocks any kind of arriving sensory stimuli and thus it enables a person to maintain good sleep.

The cerebellum is also known as the ‘little brain’. It comprises of two creased ovals located just behind the brain stem. Cerebellum’s purpose is to synchronize muscle movements that are voluntary in action. The importance of this part of the brain can be understood by the fact that   People who have cerebellar damage impacts their patients in a manner that they have trouble in walking, maintaining their balance, and attempting to keep their hands stable. Since alcohol affects the cerebellum, intoxicated people have a little more trouble walking linearly. 

In addition to this, the cerebellum has a good influence on emotions and the reactions they can cause. It also aids in noise and texture discrimination and plays a vital role in learning. Even though the brain stem’s main purpose is to monitor and control the most fundamental parts of life, such as motor skills, the limbic system is primarily important for the concept of memory and feelings, which also encompass the reactions exhibited by a person in case of reward and penalty.

The Limbic System:

The limbic system is the specific region of the brain that regulates feelings and the process of recollection (otherwise known as memory) (Figure 1). It is situated between the two cerebral hemispheres and the brain stem (pons, midbrain, and the medulla oblongata). It consists of the following structures:

  • Amygdala
  • Hippocampus
  • Hypothalamus

Amygdala:

The amygdala is made up of two clumps that are in a shape that resembles almonds, which makes sense since the word ‘amygdala’ is derived from the Latin word for ‘almond’. The amygdala is mainly in charge of managing the conceptions of, and responses to, aggressive behaviour and the sensation of being afraid. Amygdala is linked to other systems in the body associated with fear, such as the sympathetic nervous system as well as the reactions observed on the face of a person who is afraid. 

Smell interpretations and the emission of neurotransmitters associated with distress and aggressive behaviour are also sensations that are related to the functioning of the amygdala.

Besides their assistance in experiencing fear, the amygdala also facilitates humans in learning from fear-inducing circumstances. For example, when a person witnesses a somewhat dangerous situation, the amygdala triggers the brain to recognize the specifics of the predicament so that the person can avert it in case it happens again. 

Hippocampus:

This structure present in the brain is made up of two “horns” that branch off from another part of the limbic system, the amygdala.  The hippocampus is very important, so much that f in any way it is subjected to harm or some kind of injury, the affected person would not be able to produce and store new memories, and would have this difficulty embracing their life as no new information would stay intact, even if the memories before the injury are safely present. The hippocampus is essential for the formation and storage of long-term memory.

Hypothalamus:

The hypothalamus is a structure positioned just beneath the thalamus (as the name suggests). It encompasses a set of limited sections that execute several tasks, such as the monitoring and control of hunger and sexual activity. It helps in connecting the nervous system to the hormonal system with the help of the pituitary gland. 

The hypothalamus assists in controlling numerous body essentials, such as the body’s temperature, its need for food, water, and sex with the help of its several connections with certain other areas of the brain, and reacts to the fulfilment of these requirements by producing positive emotions like pleasure. 

Emotional processing:

A few decades ago, most of the research concentrated on cognition, with very little attention paid to feelings. That being said, attraction towards emotion has grown significantly, with the term affective neuroscience presently going head to head with the phrase cognitive neuroscience. In recent times, research has shifted away from studying emotion and cognition as distinct sensations and toward recognizing their interdependence.

Previous researches of brain processes involved in feelings were frequently hindered by viewing emotion as a single entity instead of as a collection of different but connected processes. As scientists continued to carry out investigations, the understanding of the human brain has advanced enough to clearly differentiate precisely defined emotional responses, and it is now possible to detect a few of the neuronal functions and structures associated with these methods with greater precision. Groundbreaking research findings in neuropsychology, for instance, indicated that the left and right hemispheres of the brain were involved differently in emotion regulation and working. 

Endogenous emotions:

Emotions are typically considered as responses factors or stimuli that originate from the external surroundings. The truth is, they quite often are created as a consequence of processes or factors that originate internally such as a person’s ways of thinking or stored away experiences. One distinguishing feature of these feelings and emotions is that voluntary production of these sensations is possible, for instance, by managing to remember some memories for highly emotional occasions. 

Endogenous emotion generation (EGE) induces subjective and psychophysiological reactions related to the nervous system that are strikingly similar to emotional reactions to external triggers, and scientists have now proposed that the production of these conditions is essential in coping and maintaining feelings.  

Differences between endogenous and exogenous emotional inhibition:

Emotion-focused methodologies have been used in social neurobiology to investigate the control and monitoring of emotions. Numerous experiments investigated respondents wanting to control emotional responses triggered by specific signals.  Individuals are frequently commanded to choose some kind of cognitive measure to reduce specific emotional responses, including the action of disassociation or reconsideration. Importantly, subjects typically receive external signals indicating if they should experience or suppress their emotions.

In daily life, nevertheless, people are very seldom advised not to express or experience feelings. One needs to probably determine to either feel or suppress their feelings. It is speculated that deliberate emotion suppression is a unique type of self-control that differs from a person’s capability to suppress emotional states in response to external supervision.

Prior studies on the control of actions provide proof of a difference between deliberate and extrinsic inhibition procedures. Numerous researches on exogenous suppression have indicated that the lateral prefrontal cortex houses an inhibiting “control process.”

Aron and Poldrack (Aron, Robbins and Poldrack, 2004) detected the right inferior frontal cortex as the fundamental part of the brain for inhibitory control in a meta-analysis of so-called Go/NoGo activities, during which respondents must react to Go stimulation while inhibiting reaction to less recurrent NoGo sensory input (Figure 2).

In experiments where participants successfully blocked their reaction, comparable lateral prefrontal brain regions, such as the inferior frontal cortex and middle frontal gyrus, were activated. Importantly, in both experimental studies, a currently underway action is inhibited.

Brain activity is seen to be triggered in the dorsal frontomedial cortex (dmPFC) when contrasting endogenous inhibition to action experiments, but it could not be seen in the lateral prefrontal regions that are connected to exogenous inhibition. A subsequent study reproduced this discovery by employing a very different concept that involved the purposeful inhibition of strongly prepotent reactions. (Kühn, Haggard and Brass, 2009)

There is no scientific proof that the difference between exogenous and endogenous inhibition needs to be applied just to actions or that it may also apply to thoughts and feelings. Nevertheless, if an endogenous type of emotion suppression can be identified, its significance for regular emotion regulation becomes evident.

A study conducted by Kuhn, Haggard, and Brass directly compared the endogenous and exogenous influence of negative emotions to tackle this problem. (Kühn, Haggard and Brass, 2009) Respondents were shown frightening images. In one situation, they were commanded to suppress or express the feelings triggered by the image, whereas, in another, people were completely independent in choosing whether to constrain or feel the emotion.

Their findings show a neural distinction between endogenous and exogenous emotional inhibition. Exogenous inhibition of negative feelings, like earlier studies on exogenous inhibition of activity, has been associated with brain operation in the lateral prefrontal cortex, specifically the middle and inferior frontal gyrus.

In this particular research, the inhibitory action of negative emotion because of endogenous factors was correlated with operation in the medial frontal cortex or dmPFC. Even though current locations are marginally more anterior, this is consistent with past findings on endogenous inhibition of action. Furthermore, it was discovered that activation in bilateral STG, a part of the brain previously reported in reappraisal research findings. This brain region has been linked to self-other differentiation. This study investigated the functional relationship of the dmPFC in order to determine the particular brain areas it controls. It was discovered that there is greater connectivity between dmPFC and preSMA during endogenous inhibition than during endogenous inhibition.

So many fMRI researches have suggested that when respondents were commanded to use a variety of cognitive techniques and methods to avoid negative emotional experiences, activity in the ventrolateral, dorsolateral, and dorsofrontomedial prefrontal cortices increased (Figure 3). Such techniques include revision and disassociation, but they all have the same effect of preventing emotional state. In this context, the goals of feeling inhibition will be far more essential than the ways to accomplish them. Scientists have focused on suppression by distance as it is not impacted by inter-individual differences or the creativity required for reimagining. The idea of disassociation, consequently, indicates that the stimulation is still evident and regarded, but the effects of emotions are avoided. 

Endogenous emotion suppression was linked to dmPFC excitation, whereas exogenous inhibition was linked to lateral prefrontal cortex activation. This distinction harkens back to the difference between neural substrates for exogenous and endogenous suppression of motor movements.

Conclusion:

The limbic system is the specific region of the brain that regulates feelings and the process of recollection (otherwise known as memory). It consists of the following structures: Amygdala, hippocampus, and hypothalamus.

Emotions are commonly regarded as response factors or stimuli that originate in the external environment. The truth is that they are frequently formed as a result of internal processes or factors, such as a person’s ways of thinking or stored experiences. Exogenous inhibition was linked to dmPFC excitation, whereas endogenous emotion suppression was linked to lateral prefrontal cortex activation. The researchers discovered a neural distinction between endogenous and exogenous emotional inhibition. Exogenous inhibition of negative feelings has been linked to brain activity in the lateral prefrontal cortex, specifically the middle and inferior frontal gyrus, as have previous studies on exogenous inhibition of activity.

Many fMRI studies have found that when participants were instructed to use a variety of cognitive techniques and methods to avoid negative emotional experiences, activity in the ventrolateral, dorsolateral, and dorsofrontomedial prefrontal cortices increased. When comparing endogenous inhibition to action experiments, brain activity was seen to be triggered in the dorsal frontomedial cortex (dmPFC), but not in the lateral prefrontal regions associated with exogenous inhibition.

Reference list

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