Monday, March 9, 2009
Borderline Personality Disorder and the Brain
Borderline Personality Disorder (BPD) is an emotional disorder. People with this disorder tend to react to situations differently; they experience intense emotions that can at times change rapidly, yet at other times they linger for a torturously long time. People with BPD may have trouble calming themselves down after feeling a strong emotion. (Linehan, 2007)
As we know from our readings, the brain can change for any number of reasons, such as genes; exposure to unhealthy conditions or substances during gestation; stressful events during infancy, childhood, or later trauma; alcohol and/or substance abuse.
The areas of the brain that may be involved in BPD include the limbic system, the prefrontal cortex, and the hypothalamic-pituitary-adrenal axis.
Limbic System and Prefrontal Cortex
As we have learned in class, the limbic system is an area of the brain that among other things, has to do with emotions, memory, and pleasure. The amygdala, the emotional center of the brain, and the hippocampus, which is involved in learning and memory, are included in the limbic system.
Studies have shown that people with BPD have smaller amygdalas, and certain areas of the amygdala are more reactive to emotional stimulation. (Schmal et al. 2003; Tebartz van Elst et al. 2003) In one study, the amygdala was monitored to see how it reacted to faces with different types of emotional expressions. People with BPD had stronger activation in their left amygdalas. (Herperts et al. 2001)
Research has shown that people with BPD also tend to have a smaller hippocampus.than those who do not. (Schmal et al. 2003; Tebartz van Elst et al. 2003) Similarly, people with post-traumatic stress disorder (PTSD) tend to have a smaller hippocampus, but people with BPD are the only ones who have smaller hippocampi and amygdalas.
The prefrontal cortex, the piece of the brain whose importance was made most famous by Phineas Gage, shows evidence that it is involved in the activity of the limbic system. In fact, this evidence seems to suggest that activity in the prefrontal cortex regulates activity in this emotional center of the brain. Research on BPD demonstrates lower activity in patients in certain areas of the prefrontal cortex when they are exposed to stressful memories. (Schmal et al. 2003) This suggests that low activity in the prefrontal cortex may not be active enough in certain ways to effectively regulate the amydala, causing the person’s intense emotions to make them feel as if they are “spinning out of control.”
The Hypothalamic-Pituitary-Adrenal Axis
The HPA axis is the other neurological system related to the brain. Both the hypothalamus and pituitary gland influence the body’s response to stress, and higher activity in the HPA axis leads to greater concentrations of cortisol, the stress hormone. A hyperactive HPA axis means a hyperactive biological stress response.
People who have BPD can get thrown over the edge over even minor stressors, and may go through periods of extremely tense irritability. In other words, they have an exaggerated stress response.
People with BPD demonstrate exaggerated cortisol responses compared to people without BPD. (Grossman, Yehuda, and Siever 1997; Lieb Rexhausen, et al. 2004.) Other research has shown that a hyperactive HPA axis may predispose people to attempt suicide. (van Heeringen et al. 2000)
Stressful and/or traumatic events can also increase the likelihood of exaggerated cortisol levels.
There are also several theories about dopamine and serotonin genes which I will talk about tomorrow in my presentation!
The Extended Mind
In their essay “The Extended Mind” (1998), Andy Clark and David J Chalmers attempt to answer the question “where does the mind stop and the rest of the world begin?” This may, in fact, be a misleading question, simply due to human preconceptions about the meaning of the word “mind” and the readiness with which we view it as interchangeable with the word “brain”. A more truthful, or comprehendible, explanation of their thesis would be: an attempt to better understand the boundaries of individual cognition. While most of us can readily understand the hypothesis that individual cognition ends where the brain ends, with the clear delineation of skull and skin, Chalmers and Clark also reference the lesser know hypothesis of semantic externalism.
Semantic Externalism and the Twin Earth Thought Experiment
Semantic externalism is a theory initially proposed by Hilary Putnam in his essay “The Meaning of ‘Meaning’” (1975); this idea was subsequently expanded on by Tyler Burge in his 1982 essay, “Other Bodies”. In his essay, Putnam asks us to imagine a parallel universe exactly the same, in every way, to our own. In this parallel universe “Twin Earth” would exist as indistinguishable from our own Earth, except for one small difference. What the inhabitants of “Twin Earth” refer to as “water” is not H20 it is, in fact, a more complex formula, referred to, within “The Meaning of ‘Meaning’,” as XYZ. Superficially, however, XYZ is also indistinguishable from H2O. Putnam is careful to note that this experiment should be set a few centuries in the past so that neither the inhabitants of Earth nor the inhabitants of Twin Earth would be capable of understanding the underlying chemical differences between the two.
Putnam’s conclusion, therefore, in the Twin Earth Thought Experiment is that the brain is incapable of processing the entirety of meaning and that certain meanings exist entirely outside the human mind (as completely external). Therefore, semantic externalism is the theory that, as Putnam so eloquently put it, “meaning ain’t all in the head”.
Clark and Chalmers are quick to distinguish their own theory of active externalism from Putnam’s, then, better known theory of semantic externalism. They also note that while the two theories are extremely different from one another, one does not necessarily preclude the other. They explain this distinction by asserting that a person’s understanding of the word “water” is based on their historical experience of water and therefore, has “no role in driving the cognitive process in the here-and-now.” Active externalism on the other hand, describes a coupling of the human organism and some external features which “play a crucial role in the here-and-now”. It is this coupling of the human organism and the external environment that composes extended cognition.
Extended cognition challenges the idea that thought is limited to the brain. To clarify, Clark and Chalmers assert that rather than taking a metaphorical picture of our environment and then considering it internally “in our heads” our internal picture is actually very limited (consider the Daniel Simons attentional focus demonstration referred to in the article “Why Google is Making Us Smarter”) and that we must constantly refer back to our environment in order to draw on the information needed for our specific purposes.
If we are playing a game of Tetris, for instance, we do not imagine the falling shape in its correct position before pressing the button to rotate it. We press the button and rotate the shape in order to figure out what the correct position would be. Pressing the button, therefore, is an epistemic action or an “action [that] alter[s] the world so as to aid and augment cognitive processes such as recognition and search.” This distinguishes it from pragmatic actions, which are taken to fulfill their own isolated purpose.
Pressing the button becomes part of our cognitive process, therefore, not separate from it. Thus our cognition extends beyond our brains to include the button. Together, our brains and the button form a coupled system which, Clark and Chalmers argue, is a “cognitive system in its own right.” If, they contend, we would have no problem considering something part of the cognitive process were it done in the head then we should have no problem considering it part of the cognitive process at all.
Extended belief takes the assertions of extended cognition and active externalism one step further. If someone keeps information written in a notepad can that information be seen as his or her belief? Clark and Chalmers have compiled a checklist of criteria necessary to define information contained within an external source as extended belief.
1. Consistency – the external source of information must be a constant in the life of the agent.
2. Accessibility – the external source of information must be readily accessible with little effort on the part of the agent.
3. Reliability – the agent must readily endorse the information provided by the source.
4. History – the agent must have endorsed the information provided by the source in the past. (Clark and Chalmers note that this fourth criterion for extended belief is arguable)
Although they do not mention it as one of their criteria, portability is mentioned as a criterion earlier in the essay. It is possible that portability is an obvious criterion for achieving accessibility.
Wrapping It Up
While the theory of the extended mind might seem flighty, an interesting subject to ponder at best, it actually has a great deal of applicability in the study of cognition. Clark and Chalmers are quick to note that the distinction that they make is not simply terminological. Clark has gone on to write a book called Natural Born Cyborgs which is centered on the idea that our current use of coupled systems and the readiness with which the brain adapts to using new tools to aid its cognitive processes all point to a very real future wherein the delineations of organic and artificial intelligence become increasingly fuzzy. Clark and Chalmers note how significant an understanding of the extended mind could be. “… explanatory methods that might once have been thought appropriate only for the analysis of "inner" processes are now being adapted for the study of the outer, and there is promise that our understanding of cognition will become richer for it. “
Monday, March 2, 2009
Please take a moment before reading the article to watch the following video. Count the number of times any of the players dressed in white pass a ball. Write the number down on a piece of paper, then continue on to the article.