Motivation and emotion/Book/2021/Limbic system and emotion

Limbic system and emotion
What role does the limbic system play in emotion?

Multimedia presentation (3 min)

Overview

Figure 1. Emotions

The limbic system in the brain is associated with controlling emotions (Catani et al., 2013). In this chapter, the limbic system's role in emotions and emotional functioning are discussed. The limbic system is a structure in the human brain that is comprised of the thalamus, amygdala, hippocampus, cingulate gyrus, hypothalamus, and basal ganglia (Hariri et al., 2000). All the parts of the limbic system are interconnected and have an impact on emotional functioning. However, it is important to note that other areas of the brain are also considered to be a part of the limbic system; but only the more prominent ones will be discussed in this chapter. To further discuss the effects of the limbic system on emotion, damage to the limbic system and the effect of damage is discussed.

Before discussing the limbic system and its effects a general idea of emotion should be established. Emotions are our psychological experience of sensory information provided by our environment (Averill, 1998). This psychological response can cause us to behave differently in response to those emotions. Emotions are experienced differently by individuals so while emotions can be labelled, the labels may not express the intensity of the subjective experience (Averill, 1998).

Focus questions: What is the limbic system? What areas of the limbic system effect emotion the most? How does damage to the limbic system effect emotions?

Limbic system structure and functions in relation to emotion

The thalamus, amygdala, hippocampus, cingulate gyrus, hypothalamus, basal ganglia, and fornix are all structures of the limbic system (Hariri et al., 2000). While all structures of the limbic system play an important role, they are all interconnected and work together. The function of each structure must be defined to better understand how the limbic system affects emotion.

Figure 2. Limbic system

Amygdala

The amygdala is close to the brain stem as shown in figure 2. The primary function of the amygdala is to send information to the hypothalamus when it is stimulated.  The process of the amygdala sending information to the hypothalamus causes a physiological reaction to take place (Morgane et al., 2005). The amygdala can be stimulated when it detects a threat in an event, but it can also be stimulated when it detects events that cause happy feelings (Cunningham & Kirkland, 2014).

Hypothalamus

The hypothalamus role is to balance bodily states so that the human body can function at its best (Pearson & Placzek, 2013). The hypothalamus (see figure 2) functions by receiving sensory information from sensory organs. However, the hypothalamus can also receive information from the hippocampus and the amygdala (Pearson & Placzek, 2013). The hypothalamus processes the information that it receives and sends messages to the endocrine system (Pearson & Placzek, 2013). The endocrine system is then able to release hormones that affect the autonomic nervous system (Pearson & Placzek, 2013). Finally, the autonomic nervous system regulates processes and changes heart rate, hunger/ thirst levels, body temperature and blood pressure (Pearson & Placzek, 2013).

Thalamus

The thalamus (see figure 2) affects emotions by receiving and relaying sensory stimuli to other areas of the brain to react to (Taber, et al., 2004). The environment provides sensory information of what you see, touch, taste and hear. However, the thalamus does not pass on sensory information of smell because there is a direct link to the olfactory cortex (Taber, et al., 2004).

Hippocampus

The hippocampus is located behind the amygdala (see figure 2). The hippocampus is useful for consolidating spatial memories, consolidation of learning and transfer of memories to long term memories (Anand & Dhikav, 2012). This aids in storing information about emotional experiences and previous reactions towards stimuli.

Cingulate gyrus

The central gyrus (see figure 2) is essential for regulating emotions and behavioural responses to sensory input (Vogt et al., 2004). The anterior cingulate cortex (ACC) and the posterior cingulate cortex (PCC) are the two divisions of the cingulate gyrus (Vogt, et al., 2004). Within the limbic system, the ACC is interconnected with the amygdala and thalamus (Vogt, et al., 2004). This connection is linked to past experiences surrounding fear and creating memory associations between stimuli and emotions (Vogt, et al., 2004). Further, the PCC has been linked to spatial memory (Vogt, et al., 2004). The central gyrus is also interconnected with the hypothalamus to regulate the autonomic nervous system when emotions of excitement, fear or anger occur (Vogt, et al., 2004).

Basal ganglia

Figure 3. Basal Ganglia and related structures

The basal ganglia (see figure 3) promotes appropriate emotional behaviour and reactions (Moors et al., 2013). The basal ganglia is made from nuclei that are interconnected to control motor functions through direct and indirect pathways (Moors et al., 2013). The basal ganglia receives information then can either inhibit or allow the thalamus to send a message to the motor cortex (Leisman, et al., 2014). The direct pathway stops inhibition, and the indirect pathway causes inhibition of the thalamus (Leisman, et al., 2014). Once a message is sent to the motor cortex the body can physically move to react to stimuli (Leisman, et al., 2014).

Fornix

The columns, crura, body and commissure are the names of the divides of the fornix (Senova, et al., 2020). The fornix (see figure 2) is a structure that has no specific function, rather it aids in the function of other areas in the limbic system (Senova, et al., 2020). Mainly the fornix aids by connecting the hippocampus and the amygdala to other structures in the brain (Senova, et al., 2020).

Limbic system mini quiz 1 Which structure is primary known for receiving and distributing sensory information? Amygdala Hypothalamus Thalamus Basal Ganglia 2 What does the direct pathway of the basal ganglia do? Causes inhibition of the thalamus Stops inhibition 3 Does the amygdala send information to the hypothalamus when stimulated? No Yes

Fight or flight response

The limbic system is widely known for its functioning in the fight or flight response. The role of the limbic system in the fight/flight response is to recognise and respond (Cannon, 1929). The limbic system does this by receiving sensory impute that comes from recognising a threat then; heightening physiologically and emotional responses (Cannon, 1929). First, the amygdala sends a message to the hypothalamus, which can then ready the body to either fight the threat or run away from potential danger (Cannon, 1929). Emotions of anger, fear have been found to arise when this response is triggered which then can lead to aggressive or avoidant behaviour (Kunimatsu & Marsee, 2012). This response is useful for humans because it allows our bodies to act quickly keeping us safe from possible harm. For a practical example, if a fierce-looking kangaroo was bouncing towards you, your flight/fight response might be stimulated. You would now physically and emotionally be prepared to either face your opponent or run.

Damage to the limbic system

Damage to the limbic system can occur in many different ways and can have serious effects on emotional health. Once damaged, areas of the limbic system that aid with emotional regulation, emotional consolidation and understanding emotional stimuli are no longer able to function normally. Memory loss and mental health issues are two main results of limbic system damage.

Kluver-Bucy syndrome

The Kluver-Bucy syndrome occurs when there is damage to the amygdala (Willis & Haines, 2018). The damage that occurs is bilateral which means that damage occurs two the amygdala on each hemisphere of the brain (Willis & Haines, 2018). The damage that is caused rendered the amygdala unable to function. The main symptoms include hypersexuality, changes in eating behaviour, hyperorality and visual agnosia (Willis & Haines, 2018). Some of the major effects that the Kluver Bucy syndrome has on emotion is emotional dullness and emotional behaviour change (Jargin, 2020). There was even a loss of fear when encountering stimuli that would induce those emotions. And there was a lack of emotional learning when a potential threat caused harm (Lilly, et al., 2014).

Case study A case study recorded by De Tiège, et al. (2005) of a 3-year-old boy shows the effects that amygdala damage can have on emotional wellbeing. Because the amygdala aids in emotional regulation when there was damage, functions that usually took place were unable to function properly. The 3-year-old child experienced irregular sleep patterns, irritability, disinhibition, and bulimia (De Tiège, et al. 2005).

Damage to the limbic system/Mental illness

Damage to areas of the limbic system can negatively impact mental/ emotional health. chizophrenia, ADHD, autism and dementia, phobias, major depressive disorder, bipolar and post-traumatic stress disorder (PTSD) are some examples of the negative effects that damage to the limbic system can have (Mohan & Mohandas, 2007). For example, in major depressive disorder (MDD) and bipolar disorder and PTSD are disorders that the limbic system plays a role in (Chen, et al., 2014). MDD and, PTSD, bipolar disorder can occur for many reasons surrounding trauma (Chen, et al., 2014). Trauma can cause the hippocampus to reduce in size which can play a part in the development of MDD (Chen, et al., 2014). In both PTSD and bipolar the fight or flight response can be triggered more easily when there is no danger present. Connections in the brain become stronger as fear is conditioned and the amygdala stores the information (Ipser et al., 2013). Further, another finding concludes the amygdala in individuals who have MDD are less sensitive to positive stimuli and more sensitive to negative stimuli (Redlich, et al., 2014).

Case study Phobias are situations that cause extreme feelings of fear due to anticipated potential harm (Schienleet, et al., 2005). While the amygdala does not cause a phobia, it does play an important role in causing physiological and emotional behaviours (Schienleet, et al., 2005). The amygdala plays an important role here by activating the fight or flight response and exaggerating the physiological and the emotional response to the threat (Schienleet et al., 2005).

How can emotion regulation be promoted in the limbic system

Figure 4. Meditation

Cognitive-behavioural therapy (CBT) and meditation are two methods for supporting emotion regulation in the limbic system. Both these methods don't require medication and are supported by research.

Meditation

Meditation is a useful practice for many emotional issues that can occur in life. mediation can be done anywhere at any time, Figure 4 shows an individual meditating in a garden. In particular, meditation can be useful for regulating emotions; emotion regulation may be useful for individuals who have dysfunction due to limbic system damage (Tang & Tang, 2020). In particular, studies have shown that meditation is able to aid in the overstimulation of the amygdala (Tang & Tang, 2020). This can help reduce the feeling of fear by increasing emotional control. While meditation is a useful practice that can be easily accessible it may not cause drastic changes in emotional wellbeing.

CBT

CBT is another method that can be used to treat patients with a wide range of mental health issues. CBT is a form of therapy that follows a process that is customised for each individual's needs (Hofmann, et al., 2012). CBT has particularly been successful in helping with; anxiety, depression and stress (Hofmann, et al., 2012).

Case study One particular study on CBT showed that after completing CBT treatment individuals with MDD showed changes in the reactivity to stimuli from the hippocampus and the amygdala which increased emotional wellbeing. (Buchheim et al., 2012).

Conclusion

The limbic system's role in emotion is to regulate emotions. The limbic system is an amazing collection of structures in our brains consisting of the basal ganglia, cingulate gyrus, hypothalamus, thalamus, amygdala, hippocampus and fornix. Each structure of the limbic system plays an important part but they all are interconnected and support each other. The main purpose of the limbic system regarding emotion is to regulate emotion. One of the most well-known ways that the limbic system regulates emotions is through the fight or flight response. But when areas of the limbic system are damaged mainly the hippocampus and amygdala things can go wrong. Mental health issues and memory issues can arise from dysfunctional emotional regulation. Schizophrenia, ADHD, autism and dementia, phobias, MDD, bipolar and PTSD can occur from limbic system damage. Damage to the amygdala can also result in emotional dullness and reduced emotional learning as in the Kluver-Bucy syndrome. However, there are ways to influence the limbic system through non-medicated processes to help promote better emotional regulation in the limbic system. Two non-medicated processes discussed are meditation and CBT. Overall the limbic system is an important set of structures for emotional regulation that should be further studied to help individuals with limbic system dysfunction to support wellbeing.

Overall mini quiz 1 Nothing can be done once the limbic system is damaged to aid emotional wellbeing. True False 2 Damage to the limbic system can result in... Mental health issues Memory loss All three options are right Kluver-Bucy syndrome 3 The flight or flight response is not beneficial in any way. True False 4 Does the hypothalamus receive sensory information? No Yes 5 The Kluver-Bucy syndrome is a result of amygdala damage. False True

See also

1. Amygdala and emotion (Book chapter, 2014)
2. Biological factors in emotional reactivity (Book chapter, 2017)
3. Emotional self-regulation (Book chapter, 2013)
4. Memory and emotion (Book chapter, 2013)
5. Mindfulness meditation and happiness (Book chapter, 2015)
6. Fear (Book chapter, 2015)

References

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External links

• How Limbic System Therapy Can Help Resolve Trauma (NICABM, YouTube)
• Sympathetic Nervous System: Crash Course (CrashCourse, YouTube)
• Kluver Bucy Syndrome (ScienceDirect)
• Emotions: limbic system (KhanAcademy)
• What Is Cognitive Behavioral Therapy (CBT)? (Kendra Cherry, verywellmind.com)
• Limbic system (Wikipedia)