This week’s readings focused primarily on the location of emotions in the human brain. In Descartes’ Error, the case studies of Phineas Gage and Elliot were discussed and compared. In The Emotional Brain, various theories of brain function and emotion were highlighted including the famous limbic system by Paul MacLean. We concluded with two research studies that used neuroimaging (PET and fMRI) to test current hypotheses regarding emotion.
In Descartes’ Error, the case of Phineas Gage was examined in depth. It is one of the most fascinating examples of brain disorder. Phineas Gage was struck by a metal rod while working on constructing a railroad in
Gage’s incredible case started a buzz in the field of brain science. Two opposing views of brain function emerged from the frenzy. The first theory stated that psychological functions, such as language and memory were not isolated to specific regions of the brain but were part of an integrated system. The second theory opposed the first theory and stated that psychological functions were found in different regions of the brain. The debate between these two theories continues to this day.
The case of Elliot occurred many years after Phineas Gage but exhibited similar effects. Elliot had frontal lobe damage and showed signs of personality change. He was able to perform normally on various memory tests used to assess frontal lobe dysfunction. He behaved and performed ‘normally’ within society. However, Elliot’s emotional state was slightly off. He was disengaged, calm, and dispassionate when recounting horrifically tragic events. He expressed no pain over the tragedy. It was clear that damage to the frontal lobe had created a blockage in Elliot’s emotional response. Do Elliot and Pineas Gage provide evidence to support the second theory of emotion? Are emotions located in specific regions of the brain? Or do these two cases support the first theory? Is the damage blocking emotional pathways connected to various regions of the brain?
The Limbic System theory of emotion is the most accepted theory today. Previous theories on emotion helped to create it. The Limbic System theory has roots in Phrenology which was the study of brain mapping. Bumps were traced on the human head dividing the brain into various functions. The theory of localization of brain functions originated out of Phrenology. Since then, numerous neuroscientists have been trying to prove (or disprove) localization. Philip Bard “carried out a systematic series of lesion studies aimed at finding just what parts of the brain are required for the expression of rage”(Le Doux 81). Bard found that the critical lesion was on the hypothalamus. He labeled it as the centerpiece of emotion.
In opposition to localization, James Papez, a
The Limbic System was developed by Paul MacLean. The hippocampus was believed to receive inputs from the external world as well as from the internal environment. The emotional experience occurred when internal and external sensations were combined together.
The Structure of Emotion paper compares two approaches to the study of emotion. Meta-analyses were conducted and the results analyzed. The basic emotion approach states that certain categories of emotion are biologically basic-inherited, reflex-like modules that cause a distinct and recognizable behavioral and physiological pattern. The dimensional approach states that these same emotional categories are part of larger biological properties such as valence, arousal, positive and negative activation, approach and withdrawal. The experimenters discovered that the right and left amygdalae were activated with the emotion fear, that the forward portions of the anterior cingulated cortex were activated by sadness, and that the basal ganglia activated the emotion disgust. The experimenters concluded from their study that in order to better understand emotion in the brain “researchers need to move from studying singular brain areas to identifying circuits, because a given brain area may be involved in more than one functional circuit” (Feldman Barrett & Wager 83). The opinions expressed in this research paper belong to the first theory that emotions are not isolated to specific regions of the brain but are a series of integrated systems.
The Functional Neuroimaging Studies of Human Emotion uses PET and fMRI to test various hypotheses about emotion. They found that the amygdala was critical to fear-related processing; the medial prefrontal cortex is involved in emotion-related decision making and emotional self-regulation, the insula is the brain’s alarm center that combines internal somatic cues with emotional experience. The experimenters concluded that some regions of the brain are involved in specific emotional tasks while others are involved in more general emotional tasks. The opinions expressed in this research paper belong to the second theory that emotions are found in different regions of the brain.
This week’s readings highlighted and discussed the two basic theories on emotion and provided research to back up both sides of the debate. However, the debate does not seem to be resolved and we do not seem to be any closer to knowing how emotions function in the brain.
Damasio, A. (1994). Descartes’ Error: Emotion, Reason, and the Human Brain.
Le Doux, J. (1996). The Emotional Brain: The Mysterious Underpinnings of Emotional Life.
Feldman Barrett, L. & Wager, T.D. (2006). The Structure Of Emotion: Evidence From Neuroimaging Studies. Current Directions in Psychological Science, Vol. 15, pp.79-83. http://www.columbia.edu/cu/psychology/tor/
2 comments:
As you noted in the later end of this paper, there has been and continues to be a great deal of mystery concerning the functions of the brain’s various components. In my opinion, one of the most significant (and certainly one of the most consistent) points common to each of the readings is the overwhelming ambiguity regarding any attempt to map the centers of the brain, particularly those responsible for emotions. As Damasio and others noted, there appears to be “no single ‘centers’ for vision, or language, or for that matter, reason or social behavior. There are ‘systems’ made up of several interconnected brain units; anatomically, but not functionally, those brains units are none other than the old ‘centers’ of phrenologically inspired theory.” (Damasio 15) However, this distinction between “systems” and “centers” has not greatly improved scientist’s ability to map the brain. Damasio later notes what I consider to be a far more significant point than other scientists appear to have considered. He notes that “there are considerable degrees of individual topographic separation” among individual brains. (Damasio 23) He compares individual brains to faces, citing that just as nearly all individuals have the same facial features, (two eyes set over a central nose over a single mouth) individual faces are infinitely diverse due to small anatomical differences. I am not suggesting that attempting to decipher the functions of the various brain structures is meaningless. I am merely noting the immense difficulty in doing so due to the variability of individuals.
Can too emotionally-charged (ADD) decision making, as opposed to emotionally-void decision-making (as in the cases discussed by Damasio) result in similar socially-debilitating outcomes?
As Damasio said, there are "systems of systems" in the brain, but does not discount that localized parts of the brain are crucially involved with certain systems. Upon reading Gage's case, I understood that there was neurological evidence or cause of his tempermant changes. From lack of knowledge on this, what intrigues me is, in 'psychological' disorders induced after a particular event, such as OCD or PTSD, how much of a role does biology play and how much does stimuli play? In people who suffer from behavioral changes due to a tragic event, without a lesion in the brain per se, how much physiological proof is there? Can tragic events change the chemistry of the brain? In which case, how does psychotherapy work? Does talking somehow re-route these biochemical patterns (molecules, synapses, local circuits, and systems)as to make the behavior habitual?
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