In the first three chapters of Descartes’ Error, Damasio relates the cases of Phineas Gage and Elliot. Phineas Gage survived an accident in which a metal rod passed through his head and Elliot had a brain tumor removed surgically. Both survived their ordeals seemingly intact with full language and motor ability. Even cognitively neither seemed to have suffered any loss of faculties. However, according to people who knew them before their traumas, both underwent complete personality change. Phineas Gage, who had been a charming man with noted leadership abilities, became socially inappropriate, prone to fits of temper and bad language, and unable to make long-term plans for himself. Elliot underwent more subtle changes. Damasio noted how remote Elliot was. His were emotional reactions nearly completely suppressed and strangely even Elliot had noticed this change in himself. Elliot participated in experiments that showed that he had the knowledge of what a good decision would be across a variety of different situations but he was unable to make advantageous decisions for himself. Both cases suggest that the disruption of a brain system disabled social and decision-making abilities in both men. Though they both had the experience and knowledge of social norms, they were unable to make use of it. Damasio asks the questions: what was disabled in both men and, even more basic, what are the usual basic steps in decision-making for human beings whose brains are intact?
In chapter 4 of The Emotional Brain, LeDoux recounts the search to identify what process in our brains accounts for our experience of emotions and ends by reorienting it. Gall had the insight that “functions [in the brain] are localized,”(p. 76), that is that each part of the brain has specific functions. However, we now know that processes are not limited to specific areas of the brain but involve networks comprised of interacting areas. Damasio describes MacLean’s limbic system theory as having enormous influence on research up until now but explains why it is inaccurate. MacLean’s theory posited that the limbic system integrated our external and internal experience and that our emotions come out of the system. LeDoux believes that an aspect of MacLean’s theory is correct: the influence of evolution (continuity between animals and human beings that Darwin proposed) is observable in the brain. Emotions are brain functions that are beneficial to our survival. But, as he says, MacLean looked too broadly at emotions in positing that all were the result of one system. Rather, “…different emotions are involved with different survival functions…” and probably involve many specialized emotional systems in the brain. (p. 103)
The article Functional Neuroimaging Studies of Human Emotions (2004) evaluates the findings of several neuroimaging studies. Phan, Wager, Taylor and Liberzon write about the findings that observed activation of specific brain structures, anticipated to be part of the neural basis of emotion, focusing mainly on limbic structures. The authors conclude that the findings suggest that certain brain structures may be involved in specific and some in more general emotion-related tasks. In the future, the authors believe more fine-tuned imaging techniques will allow researchers to identify the interconnections of brain areas in an “emotion network.”
The last article, The Structure of Emotion, looks at the evidence so far from neuorimaging studies already conducted using fMRI and PET by comparing the findings of two meta-studies.. Barrett and Wager begin the article with the question, “What are the basic building blocks of emotional life….?” and describe two central theories. The first theory (as in Paul Ekman’s work) is that there are inheritable basic categories of emotion: anger, fear, sadness, happiness and disgust. The second theory seeks to identify in the brain signs of dimensions of emotional response. The dimensions considered are: valence (pleasure/displeasure), positive or negative activation, or approach and withdrawal. To establish evidence in support of either theory, what is needed is to be able to identify patterns of activation that are consistent and specific.
It seems from this study that previous findings do not conclusively establish or rule out either of the two theories. The authors suggest that possibly a new model should be investigated, perhaps one based on “stimulus salience. “ (I’m not sure what this is.)
They end their article by recommending issues to be considered in future studies. They point out that the technology is getting much more refined, allowing much more specific study of functional regions. This may help distinguish between emotions reflected in the activity of structures of the brain. They urge researchers to study circuits rather than specific brain areas. They also point out that in looking at brain activity researchers may be observing the brain doing more than purely responding emotionally and that researchers are getting better at identifying confounding factors. Researchers need to refine their inferential process. In brain mapping they seek to evoke a certain emotional response (fear) and look to see if a certain brain structure responds (amygdala.) But whenever the amygdala is activated, is there fear?
Their final point is a fascinating one, challenging scientists to dismantle the conceptual framework for what they are looking for. Perhaps our “emotion words” (fear, sadness, happiness, etc.) do not map out to distinct events in the brain. As I understand it, the authors suggest that researchers might look at brain responses to conceive a new understanding: observe how emotions created from psychological processes play out in neural systems, then allow this understanding to reshape how we conceive of emotions.
This last article raises the issue Elizabeth and Leah were suggesting we look at next, the role of language in understanding emotion. How specific is our language for emotion really? Are even emotions we understand as easily distinguishable from others (happiness, for example), really an experience as distinct from other emotions in our actual brains as we conceive it to be?
When LeDoux posits the existence of many emotional systems in the brain does this fit within Phan, Wager, Taylor and Liberzon’s idea that there is an “emotional network”?
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4 comments:
When looking at the marriage between language and emotion, I would say that most cultures have a very specific vocabulary for their emotions. The act of putting feelings into words is something that begins developing (or not developing) early on. We must communicate that we are hungry or have to go to the bathroom at a young age and do so by acting out emotionally. Soon language is also used to describe what is going on and without a vocabulary for emotions, how can we communicate them? Even if the language of emotion is not a particularly successful one, it is still there and we do use it on a daily basis. Do we all have the same emotional vocabulary? If not, is it possible to create a universal language to properly capture what we're feeling? It is hard because sometimes emotions do not seem to be able to be put into words, but then aren't there other ways of expressing one's self? Does dance or music or painting or mathematical equations properly represent emotions in a way that words will never be able to?
I think "stimulus salience" is just referring to the level of arousal. What's a bit confusing to me is the dimensional approach: what is the difference between arousal and positive activation? What is approach and withdrawl? I'm sure they're relatively simple concepts, but the authors could have included a short clarification for such underprivileged readers as myself. Regardless, though, I think the dimensional approach is important in light of the difficulties of categorizing an emotion. The "Functional Neuroimaging Studies of Human Emotions" article highlights numerous contingencies under which many patterns of neural activation can be seen, and the "Structure of Emotion" reminds us of the uncertainties and inconsistencies of these studies. It is natural that one should ask the question, what is happiness on the neurological level? or what is any emotion for that matter? If the amygdala or any other structure is activated unconsciously can we really say that "emotional meaning" has been transmitted?
Also: have any MEG studies of emotion been conducted? I would think that the quality temporal resolution would give better sense of activation of a whole circuit.
And what about the remark saying it's necessary to test whether the emotion is present when the structure is activated? Is this the logic of all neuroscience? And what's the deal with Elliot??
When I first began reading Demasion my initial question was if a person who had experienced a dissociation in behavior, like Phineas Gage, could understand or comprehand their altered state. However, as we later learn about Elliot, this question required reconsideration. Elliot was aware of his character changes regarding his actions/emotions, he was able to differentiate right and wrong on a non-personal level, yet unable to incorporate such comprehensions into his own behavior. Who knew that it is not enough for the brain to distinguish the proper emotional reactions for specific situations, but that we depended on another brain function to incorporate such perceptions into ones behavior.
I'm really interested in the point that Amy brings up (and I mentioned this in our first paper too) that maybe catagorically we have it all wrong. Different brain regions contain different emotions, yet divide them in specific ways that may be suprising. Our common impression that emotions are all different and our brain therefore responds separately to each one is false. It is also wrong, as the functional neuroimaging article points out, that all of our emotional processes take place in one brain region, even though 50% take place in the MPFC and can also be connected to this region. I think that this way of thinking is very beneficial for future biological studies of the brain, just to have a basic understanding and skepticism that emotions and brain functions are not always generalized, or easily catagorized, to any specific region or function. That some processes might be separated, interconneted or grouped in ways that we would have never conceived of. This is kind of related to what Matt was saying, but I think its kind of hard to critique how an emotion is gaged on a biological system, or even how to begin to understand that process of determining emotions on a neurological scale, if our impression of emotions is still bound up in false catagories.
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