Motivation and emotion/Book/2015/Prefrontal cortex and emotion

Overview
Emotions are important aspects of everyday life as we feel a variety of different ones across the span of just one day. But many people do not know why or how we experience emotions. Why are some people always happy no matter the situation? Why do I have to experience sadness and fear? Why are teenagers so moody? Why do people’s emotions change after accidents? These questions are all related to the functioning of the prefrontal cortex.

The prefrontal cortex is one of the main areas of the brain responsible for the processing and regulation of emotions. This chapter will focus on the core question of what role does the prefrontal cortex play in emotion? Which in turn will look at the introductory concepts of emotions and the prefrontal cortex, theoretical explanations explaining the individual differences between emotions, the changes of emotions throughout development, and the emotional limitations due to injuries of the prefrontal cortex. All which place an emphasis on the fact that everyone experiences situations differently. Some cope well when others do not. But all emotional experiences are not meant to be embarrassing or shameful, they are just a form of the body’s natural reaction.

Prefrontal Cortex


The prefrontal cortex is the area of the brain responsible for higher cognitive and executive functioning such as perception, planning ahead, emotional regulation and top-down processing (Miller & Cohen, 2001). It is the part of the brain that stores our thoughts, goals and memories across the left and right prefrontal cortex (Gianotti et al., 2009).

The left prefrontal cortex often produces positive emotions and the “go” approach motivation, while the right prefrontal cortex produces negative emotions and the “no-go” avoidance motivation (Miller & Cohen, 2001). These differences can indicate which side of the cortex will be displaying more activity depending on the situation someone is in. If someone sees a friend they have not seen in awhile, they are likely to feel happy and go and speak to them. This means their left cortex will be more activated because they are feeling happy which is a positive emotion. However, each individual may be more inclined to have one side of the cortex more sensitive than the other (Gianotti et al., 2009).

The prefrontal cortex is also further differentiated into four main parts with different functions. The orbitofrontal cortex and the ventromedial prefrontal cortex are highly recognised as important regions of the prefrontal cortex in terms of explaining its significance towards emotion (Bechara, Damasio & Damasio, 2000). These are displayed in Table 1.

Table 1. The functions of the prefrontal cortex.

Emotion


Emotions are short-lived but very complex conscious mental states or reactions to external life situations (Reeve, 2015). Life events trigger neural activity that produces emotional reactions (Reeve, 2015). When receiving a good grade many people will express the emotion of happiness and joy, while being fired from your job may lead to anger or disappointment. Emotions are often the result of a direct and specific event (Klimes-Dougan et al., 2014). They help express the body’s reaction to stimuli and can result in physiological and behavioural changes (Vandenberghe & Silvestre, 2014). For example if you feel excited, physiologically your heart may start to race, and behaviourally, you may begin to smile and jump up and down. When you are sad, physiologically you can feel fatigued, and behaviourally you may cry and isolate yourself. Cognition also plays an important role in understanding emotion. For example, a racing heart rate is a physiological response for excitement and anger. Therefore, cognition allows individuals to differentiate and identify the emotions they are experiencing (Vandenberghe & Silvestre, 2014).

Emotions are also often displayed through facial expressions that allow others to interpret what you are feeling. Paul Ekman identified six primary emotions that are universally communicated across many different cultures. The six emotions include anger, happiness, disgust, surprise, sadness and fear (Sabini & Silver, 2005). More recently, contempt was added to make seven primary emotions that can occur instantly and involuntarily (Reeve, 2015). Ekman is one of the more famous theories of emotion but other theorists have suggested different numbers, such as five or even eight cross-cultural emotions (Reeve, 2015).

Emotions can often be described as positive, such as interest and enthusiasm, or negative, such as hatred and regret. While they are known as positive and negative emotions, they are not necessarily good or bad (Klimes-Dougan et al., 2014). Research has shown the importance of experiencing both kinds of emotions, as you cannot go through life feeling only one type of emotion and not the other (Vandenberghe & Silvestre, 2014). Table 2 provides examples of why both positive and negative emotions are fundamental to coping with life experiences.

Table 2. Fundamental View of Emotional Behaviour (Reeve, 2015).

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Gray's Biopsychological Theory of Personality
Gray proposed a theory made up of two systems that help continue the discussion of the differences between the left and right prefrontal cortex. He developed this theory to explain concepts such as personality traits in a more physiological way (Gable, Reis & Elliot, 2000). The behavioural inhibition system (BIS) and the behavioural activation system (BAS), contribute to empirical research findings that state each individual can be more sensitive on one side of their prefrontal cortex, which in turn relates to their emotional experiences.

Behavioural Inhibition System (BIS)
The behavioural inhibition system is evident when someone has a more active or sensitive right prefrontal cortex, with susceptibility to negative cues (DeYoung, 2010). These people are likely to experience more negative emotions, display avoidant behaviour, are more attuned to punishment and may experience anxiety (Carver & White, 1994). The BIS provides the capacity to become aware of potential negative consequences which then motivates the withdrawal, avoidance and caution by provoking negative emotionality (DeYoung, 2010).

Behavioural Activation System (BAS)
The behavioural activation system is clear when there is more activation in the left prefrontal cortex, showing a susceptibility to positive cues (DeYoung, 2010). This system is connected with positive emotions, goal-orientated behaviours, rewards and a likelihood of impulsivity (Carver & White, 1994). The BAS provides the capacity to approach behaviours that are centered around goals due to positive emotionality (DeYoung, 2010).

James-Lange Theory


The James-Lange theory is that we feel physiological arousal and responses before we experience emotion (Moors, 2009). They theorised that emotions are felt based on the intensity of the physiological experience, and that each emotion has its own response pattern that occurs due to a stimulus (Moors, 2009). This theory has been criticised, however, for being unable to explain where these physiological responses are first elicited. Other researchers have stated that there needs to be some form of processing between the physiological response and the subsequent emotion (Moors, 2009). For example, an individual would need to draw on previous experience, environmental cues and have an understanding of the context before knowing which emotion to react with (Moors, 2009). All of this requires the prefrontal cortex’s abilities such as social judgment, decision-making and working memory. These criticisms help highlight the need of a functioning prefrontal cortex in order to process emotions.

Dynamic Filtering Theory
Shimamura (2000) developed the dynamic filtering theory in order to determine what type of role the prefrontal cortex, and more specifically the dorsolateral prefrontal cortex, played in memory and cognitive concepts. It was discussed that selecting, maintaining, updating and rerouting were four aspects responsible for executive control (Shimamura, 2000). These findings led to the belief that the prefrontal cortex uses selective filtering or gating in an attempt to control information processing (Shimamura, 2000).

It was also found that this theory could be useful in explaining the prefrontal cortex's role in emotional regulation. Broadening his theory to include emotion was influenced by the events that happened to Phineas Gage. Gage's damage to the orbitofrontal cortex was strongly correlated with his ability to control and regulate their emotions (Shimamura, 2000). For example, this theory would explain that emotional outbursts are due to the inability to filter or gate incoming information. Therefore, something is happening to prevent regulation in areas of the brain such as the orbitofrontal cortex that are responsible for emotional expressions (Shimamura, 2000). Research studies have indicated that this could be occurring due to damage or perhaps even the underdevelopment of the prefrontal cortex.

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Development of the prefrontal cortex
Research has consistently stated that the brain is not fully developed until around the age of 25 (Yifang, Hongyun, & Yanjie, 2014). This means that as people grow older their prefrontal cortex is slowly developing and so is their emotional maturity. Emotional maturity is often measured by someone’s ability to regulate his or her emotions through their understanding of them. While emotional regulation involves being able to identify or change emotions based on duration and intensity, and to have the ability to recover from them (Zimmermann & Iwanski, 2014). Key distinctions can be made in terms of emotional development at certain milestones throughout life.

Childhood
In one study it was found that children had developed an understanding of basic emotions, similar to those of Paul Ekman’s seven primary emotions. The study found that children who were of preschool age were significantly better at identifying positive emotions such as happiness, rather than negative emotions such as anger (Yifang et al., 2014). Although, when identifying feelings out of two negative emotions, the study found that the children would understand anger before they understood fear (Yifang et al., 2014). The emotions that children were able to identify and comprehend were always the simplest out of the two options. They indicated that at this age there was a strong development in emotional maturity for two years, and then the participants began to steady their emotional development (Yifang et al., 2014). These findings indicate that a beneficial research study could be conducted on the prefrontal cortex to see if the left side develops quicker than the right, or conclude that these findings may be reduced to just this study. Either way, studies have shown that during childhood, children are able to grasp a wider variety of basic emotions compared to infancy.

Adolescence


During adolescence there can be an increase in both avoidant and impulsive behaviour (Zimmermann & Iwanski, 2014). During this time emotional regulation is not as effective, likely due to the prefrontal cortex still developing. This period in the lifespan displays the most instability emotion-wise. As teenagers start to develop, they experience an influx of negative emotions due to changes in relationships with peers and parents (Zimmerman & Iwanski, 2014). This can be a difficult time due to the fact that throughout childhood they would have been feeling predominately positive emotions and only basic negative emotions (Yifang et al., 2014). Now emotions will start to become more complex. They also have not necessarily developed efficient emotion regulation strategies, for these emotions that they have not experienced as often such as regret (Zimmermann & Iwanski, 2014).

One very informative point that emphasises the importance of the prefrontal cortex in emotion is that other areas of the brain such as the amygdala develop before the prefrontal cortex (Sieb, 2013). The amygdala is another part of the brain that is substantially involved with emotions, but does not contribute to the regulation and control of emotions as much as the prefrontal cortex does (Sieb, 2013). Its role is associated with emotions that are more intense such as fear and aggression, and they are triggered quite quickly (Sieb, 2013). Adolescents are often linked to impulsive and risky behaviour, and as stated before they have difficulties regulating their emotions. Based on research, teenagers are behaving this way because they have the capacity to feel these emotions, but they do not have the ability to regulate them yet (Sieb, 2013). When people reach adulthood it is more likely that their emotions will start to settle and become more manageable.

Adulthood
During most of the adult era the brain is completely developed and functioning properly, which means that emotional maturity and regulation, is at the highest level. Research has shown that life experiences allow people to develop strategies to help regulate their emotions (Zimmermann & Iwanski, 2014). Put more simply, people learn how to cope with the negatives and enhance the positives. By the time people reach adulthood they would have experienced a variety of events eliciting a wide variation of emotions. This means in conjunction with the prefrontal cortex’s cognitive abilities, people develop empathy and they have an understanding of their own emotional triggers (Zimmermann & Iwanski, 2014). At this stage in life, people have likely developed a tendency to lean towards either the BIS or BAS, which they may or may not be aware of (Zimmermann & Iwanski, 2014). It has however been mentioned that differentiating between adolescent and adult emotional maturity can be difficult due to personal differences. Personality, in terms of openness, conscientiousness, extraversion, agreeableness and neuroticism can sometimes affect an individual’s ability to regulate their emotions even in adulthood (Zimmermann & Iwanski, 2014). Which means that not all adults have necessarily developed effective regulation strategies, which indicates the dynamic filtering model's validity in these cases. This proves that while adulthood results in a fully function cortex, it may function differently between person to person.

Later Life
Older age is the stage when emotions are at their most stable and regular state. Middle to late life is when people can display an increase of self-control and high conscientiousness in terms of their emotional regulation and maturity (Zimmermann & Iwanski, 2014). However, there can be a decline due to illnesses that occur in old age, such as dementia. When the prefrontal cortex is no longer functioning properly due to illness, someone’s emotional maturity can revert back to earlier stages involving a common presence of negative emotions, or new emotional issues may arise (Zimmermann & Iwanski, 2014). These effects that are attributed to illness are similar to those of damaged prefrontal cortices which will be discussed further.

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Damage to the prefrontal cortex
In 1848 a man named Phineas Gage experienced one of the most famous and bewildering neurological injuries of all time. He was blasting holes into rocks to make way for a new railway when the accident occurred. One of the blasts went off unplanned and the iron rod he was using went through the left side of his face, up past his left eye and protruded through the top of his head. The reason this case is so famous and puzzling is that not only did Gage not die, shortly after he was able to sit up and speak to the doctor when he arrived. Research has shown that the iron rod went up through the prefrontal cortex and more specifically the orbitofrontal region. After the accident, the damage to his brain proved to have drastic effects on him both psychologically and behaviourally. He was described as impatient and rude, he used profanities, was unable to finish tasks and his mind was unbalanced. These characteristics were not present before the accident. Due to the prefrontal cortex playing such an important role in emotion, it was likely Gage’s emotions were also going to be effected. It has been reported that he had difficulty processing emotions and he lost his emotional inhibition, meaning he was likely to behave inappropriately at emotionally sensitive times. He also had difficulties with his emotional intelligence, which meant he struggled to recognise emotions and manage them. This evidence ties in with the left prefrontal cortex’s ability to control positive emotions as Gage was expressing negative emotions when most people would experience positive ones, and the BAS being goal-orientated as his had difficulties completing tasks.

- Ratiu, Talos, Haker, Lieberman & Everett, 2004; Sigglekow, 2007.



Empirical Research
When trying to understand how a certain brain structure functions or what aspects of daily life it is responsible for, it is common for research to be conducted when that structure is no longer there or when it is not functioning adequately. Research has consistently shown that damage to the prefrontal cortex can result in a lack of emotional awareness, regulation and processing.

Sanchez-Navarro and colleagues (2014) found that it was harder to process emotions when damage had occurred to the cortex. Their study consisted of participants being shown pictures of emotionally evoking stimuli, and it was discovered that those with damage to the prefrontal cortex had trouble maintaining their attention towards the emotional material (Sanchez-Navarro et al., 2014). Understanding and feeling emotions is normally seen as an automatic process, however some participants struggled to do this. Upon investigating their participants profiles, it was also found that in this particular study participants who had experienced damage to their cortex during childhood, found it to be substantially debilitating in comparison to the other participants who faced their damage in adulthood (Sanchez-Navarro et al., 2014).

Further research has been conducted involving the use of specific emotions. Empathy is the ability to recognise and share emotions, and it is an important aspect involved with interpreting emotions. Vandekerckhove et al (2014) found that impairments to the ventromedial prefrontal cortex meant there was a greater likelihood that the participant would have difficulties interpreting emotions through facial recognition. This was especially evident when the participants were asked to identify fear, disgust and surprise (Vandekerckhove et al., 2014). Other studies looking at facial recognition reported that damage to the orbitofrontal cortex also resulted in difficulties in distinguishing between different emotions (Willis, Palermo, McGrillen, Miller, 2014). Again, the emotions that were the most problematic were negative emotions, similar to Vandekerckhove’s et al (2014) study. However, they proved to be the most difficult when displayed for a short amount of time, and the results improved when the participants were given more opportunity to identify them (Willis et al., 2014). These studies provide an interesting comparison to Phineas Gage’s emotional limitations, where only the left side of the prefrontal cortex was severely damaged.

These studies, among many others continue to show how important the prefrontal cortex is in terms of understanding and interpreting emotions. They demonstrate that the cortex plays a significant role in the way emotions function. Without the cortex operating efficiently people are likely to experience differences in their emotional abilities.

Lobotomy
Lobotomies are a type of psychosurgery that were performed in order to help cure mental disorders by reducing their symptoms. The procedure was carried out by using a leucotome that was placed either through a hole that had been drilled into the skull or placed under the eyelid, which would then sever the fibres connected to the cortex (Older, 1974). Lobotomies were used for many disorders like anxiety which can involve a heighten sense of emotion, but once the procedure was conducted patients were left with little complexity and intensity of emotional responses (Freeman, Watts, & Hunt, 1942). Lobotomies can be interpreted as damage to the prefrontal cortex even though they were deliberately performed. This outdated method indicates again that the prefrontal cortex plays a substantial role in what we feel everyday.

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Conclusion
Emotions are a significant part of everyone’s lives. Many people probably cannot imagine a life without happiness. It is important to remember that we feel emotions for a reason, whether it is sadness or joy. They are simply a natural reaction to life events that everyone should embrace. The prefrontal cortex’s development and limitations show that emotions are often out of our control. With theoretical explanations proving that everyone is different in terms of their emotional experiences. If you struggle with your emotions take a look at some self-help tips for personal growth and improvement. Do the things you enjoy and accept the feelings that are not always pleasant, as they will pass.