Affective neuroscience is the study of the neural mechanisms of emotion. This interdisciplinary field combines neuroscience with the psychological study of personality, emotion, and mood.^[1]

Brain areas related to emotion

Emotions are thought to be related to activity in brain areas that direct our attention, motivate our behavior, and determine the significance of what is going on around us. Pioneering work by Paul Broca (1878),^[2] James Papez (1937),^[3], and Paul D. MacLean (1952)^[4] suggested that emotion is related to a group of structures in the center of the brain called the limbic system, which includes the hypothalamus, cingulate cortex, hippocampi, and other structures. Research has shown that limbic structures are directly related to emotion, but non-limbic structures have been found to be of greater emotional relevance. The following brain structures are currently thought to be involved in emotion^[5]:

• Amygdala The amygdalae are two small, round structures located anterior to the hippocampi near the temporal poles. The amygdalae are involved in detecting and learning what parts of our surroundings are important and have emotional significance. They are critical for the production of emotion, and may be particularly so for negative emotions, especially fear.^[6]
• Prefrontal cortex The term prefrontal cortex refers to the very front of the brain, behind the forehead and above the eyes. It appears to play a critical role in the regulation of emotion and behavior by anticipating the consequences of our actions. The prefrontal cortex may play an important role in delayed gratification by maintaining emotions over time and organizing behavior toward specific goals.^[7]
• Anterior cingulate The anterior cingulate cortex (ACC) is located in the middle of the brain, just behind the prefrontal cortex. The ACC is thought to play a central role in attention, and may be particularly important with regard to conscious, subjective emotional awareness. This region of the brain may also play an important role in the initiation of motivated behavior.
• Ventral striatum The ventral striatum is a group of subcortical structures thought to play an important role in emotion and behavior. One part of the ventral striatum called the nucleus accumbens is thought to be involved in the experience of goal-directed positive emotion. Individuals with addictions experience increased activity in this area when they encounter the object of their addiction.
• Insula The insular cortex is thought to play a critical role in the bodily experience of emotion, as it is connected to other brain structures that regulate the body s autonomic functions (heart rate, breathing, digestion, etc.). This region also processes taste information and is thought to play an important role in experiencing the emotion of disgust.
• Cerebellum - Recently, there has been a considerable amount of work that describes the role of the cerebellum in emotion as well as cognition, and a "Cerebellar Cognitive Affective Syndrome" has been described.^[8] Both neuroimaging studies as well as studies following pathological lesions in the cerebellum (such as a stroke) demonstrate that the cerebellum has a significant role in emotional regulation. Lesion studies^[9] have shown that cerebellar dysfunction can attenuate the experience of positive emotions. While these same studies do not show an attenuated response to frightening stimuli, the stimuli did not recruit structures that normally would be activated (such as the amydala). Rather, alternative limbic structures were activated, such as the ventromedial prefrontal cortex, the anterior cingulate gyrus, and the insula. This may indicate that evolutionary pressure resulted in the development of the cerebellum as a redundant fear-mediating circuit to enhance survival. It may also indicate a regulatory role for the cerebellum in the neural response to rewarding stimuli, such as money,^[10] drugs of abuse,^[11] and orgasm.^[12]

Role of the Right Hemisphere in Emotion

The Right Hemisphere has been proposed over time as being directly involved in the processing of emotion. The role the right hemisphere plays has developed over time and resulted in several models of emotional functioning. C.K. Mills was one of the first researchers to propose a direct link between the right hemisphere and emotional processing, having observed decreased emotional processing in patients with lesions to the right hemisphere.^[13][14] Emotion was originally thought to be processed in the limbic system structures such as the hypothalamus and amygdala.^[15] As of the late 1980s to early 1990s however, neocortical structures were shown to have an involvement in emotion.^[16] These findings led to the development of the Right Hemisphere Hypothesis and the Valence Hypothesis.

The Right Hemisphere Hypothesis

The Right Hemisphere Hypothesis asserts that the right hemisphere of the neocortical structures is specialized for the expression and perception of emotion.^[17] The Right hemisphere has been linked with mental strategies that are nonverbal, synthetic, integrative, holistic, and Gestalt which makes it ideal for processing emotion.^[18] The right hemisphere is more in touch with subcortical systems of autonomic arousal and attention as demonstrated in patients that have increased spatial neglect when damage is associated to the right brain as opposed to the left brain.^[19] Right hemisphere pathologies have also been linked with abnormal patterns of autonomic nervous system responses.^[20] These findings would help signify the relationship of the subcortical brain regions to the right hemisphere as having a strong connection.

The Valence Hypothesis

The Valence Hypothesis acknowledges the right hemispheres role in emotion, but asserts that it is mainly focused on the processing of negative emotions whereas the left hemisphere processes positive emotions. The mode of processing of the two hemispheres has been the discussion of much debate. One version suggests the lack of a specific mode of processes, stating that the right hemisphere is solely negative emotion and the left brain is solely positive emotion.^[21] A second version suggests that there is a complex mode of processing that occurs, specifically that there is a hemispheric specialization for the expressing and experiencing of emotion, with the right hemisphere predominating in the experiencing of both positive and negative emotion.^[22][23] More recently, the frontal lobe has been the focus of a large amount of research, stating that the frontal lobes of both hemispheres are involved in the emotional state, while the right posterior hemisphere, the parietal and temporal lobes, is involved in the processing of emotion.^[24] Decreased right parietal lobe activity has been associated with depression^[25]and increased right parietal lobe activity with anxiety arousal.^[26]The increasing understanding of the role the different hemispheres play has led to increasingly complicated models, all based some way of the original valence model.^[27]

Relationship to cognitive neuroscience

In its broadest sense, cognition refers to all mental processes. However, the study of cognition has historically excluded emotion and focused on non-emotional processes (e.g., memory, attention, perception, action, problem solving and mental imagery).^[28] As a result, the study of the neural basis of non-emotional and emotional processes emerged as two separate fields: cognitive neuroscience and affective neuroscience. The distinction between non-emotional and emotional processes is now thought to be largely artificial, as the two types of processes often involve overlapping neural and mental mechanisms.^[29] Thus, when cognition is taken at its broadest definition, affective neuroscience could also be called the cognitive neuroscience of emotion.

Affective neuroscience and learning

There are many ways affect plays a role during learning. Recently, affective neuroscience has done much to discover this role. Deep, emotional attachment to a subject area allows a deeper understanding of the material and therefore, learning occurs and lasts.^[30] When reading, the emotions one is feeling in comparison to the emotions being portrayed in the content affects ones comprehension. Someone who is feeling sad will understand a sad passage better than someone feeling happy.^[31] Therefore, a student s emotion plays a big role during the learning process.

Emotion can also be embodied or perceived from words read on a page or a person s facial expression. Neuroimaging studies using fMRI have demonstrated that the same area of the brain being activated when one is feeling disgust is also activated when one observes another person feeling disgust.^[32] In a traditional learning environment, the teacher's facial expression can play a critical role in students' language acquisition. Showing a fearful facial expression when reading passages that contain fearful tones facilitates students learning of the meaning of certain vocabulary words and comprehension of the passage.^[33]

See also

• Affect (psychology)
• Affective science
• Affective spectrum
• Emotion
• Music therapy
• Psychophysiology
• Psychology
• Psychiatry

References

Further reading

• Davidson, R.J., & Irwin, W. (1999). The functional neuroanatomy of emotion and affective style. Trends in Cognitive Science, 3, 11-21.
• Freitas-Magalhaes, A. (2009). Emotional Expression: The Brain and The Face. Porto: University Fernando Pessoa Press. ISBN 978-989-643-034-4
• Panksepp, J. (1992). A critical role for affective neuroscience in resolving what is basic about basic emotions. Psychological Review, 99, 554-60.
• Harmon-Jones E, & Winkielman P. (Eds.) Social Neuroscience: Integrating Biological and Psychological Explanations of Social Behavior. New York: Guilford Publications.
• Cacioppo, J.T., & Berntson, G.G. (2005). Social Neuroscience. Psychology Press.
• Cacioppo, J.T., Tassinary, L.G., & Berntson, G.G. (2007). Handbook of Psychophysiology. Cambridge University Press.
• Panksepp J. (1998). Affective Neuroscience: The Foundations of Human and Animal Emotions (Series in Affective Science). Oxford University Press, New York, New York.
• Brain and Cognition, Vol. 52, No. 1, pp. 1 133 (June, 2003). Special Issue on Affective Neuroscience.

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