Archive for November, 2007
Terror Management, Death and Psychological Immune response
Nov 2nd
There is a new article in Time that reports on a new study that found that when people are confronted with existential anxiety provoked by thoughts of their imminent death, then instead of becoming sad, they paradoxically become happier, although the effect is subconscious.
Here’s one for the annals of counterintuitive findings: When asked to contemplate the occasion of their own demise, people become happier than usual, instead of sadder, according to a new study in the November issue of Psychological Science. Researchers say it’s a kind of psychological immune response — faced with thoughts of our own death, our brains automatically cope with the conscious feelings of distress by non consciously seeking out and triggering happy feelings, a mechanism that scientists theorize helps protect us from permanent depression or paralyzing despair.
It might explain the shift toward more positive emotions and thought processes as people age and approach death, and the preternaturally positive outlook that some terminally ill patients seem to muster.
There is a plenty of literature on Terror Management Theory that posits that when confronted with thoughts of our death (and the corresponding terror) we manage that terror by reaffirming our cultural identities and sense of self-esteem. The culture, and self esteem, presumably provides a meaning to our lives and as such are helpful in alleviating the terror of self death. The researcher, DeWall, was experimenting on TMT, when he came across this phenomenon, which has been dubbed as a psychological immune response. In the test, the affect , after mortality salience, was measured by having the students fill words that could either be filled as positive words or as neutral/ negative words. this is a good test of unconscious affect and they found that those exposed to mortality salience condition had unconscious positive affect.
About half of the students were asked to contemplate dying and being dead, and to write short essays describing what they imagined happening to them as they physically died. The other half of the group was asked to think and write about dental pain — decidedly unpleasant, but not quite as threatening. The researchers then set about evaluating the volunteers’ emotions: First, the students were given standard psychological questionnaires designed to measure explicit affect and mood. Then they were given assessments of nonconscious mood: in word tests, volunteers were asked to complete fragments such as jo_ or ang_ _ with letters of their choice. Some word stems were intended to prompt either neutral or emotionally positive responses, such as jog or joy; others could be filled in neutrally or negatively — angle versus angry. In a separate word test, students paired a target word such as mouth with its best match: cheek, which is similar in meaning, or smile, which is similar in positive emotional content.
Another important finding the team found was that in depression, the psychological immune system is dysfunctional. thus, depressive people may go in a downward spiral as they contemplate their inevitable death or other social/ personal threats to their self-esteem etc.
In his current research, DeWall is finding that other threats, such as that of social rejection, elicit a similar psychological immune response — except, intriguingly, in depressed people — and he thinks that it’s a mechanism that healthy people are probably employing constantly, as a way of fending off a lifetime of serious misfortunes: not just the looming specter of death, but also the fact that you’re not going to get that promotion, or that your spouse is cheating on you, or that your kid is on drugs. “It’s very difficult to keep people in bad moods, and I think this is one of the reasons why,” says DeWall. “Let’s say we didn’t have this. I think we would have a lot more difficulty coping with failure and threats and our own mortality. It would be difficult for us to find solutions. We would be thinking about how bad we were feeling all the time.”
Consciousness continued: what vegetative patients can tell us about it.
Nov 1st
A recent New Yorker article discusses patients in a vegetative or minimally conscious state and what the recent research about their consciousness status can inform us about consciousness in general. The article starts with the much publicized research of Owen’s group that found that a woman, in a vegetative state, responded to verbal instructions and could imagine playing tennis. It also discusses what blindsight and neglect can tell us about (un)consciousness.
In the nineteen-eighties, researchers determined that patients who had the syndrome—now called “neglect”—could process some objects in the left field of vision. In one experiment, a patient was shown two pictures of a house. The images were identical except that, in one, flames were emerging from a window on the left side of the façade. The patient said that she couldn’t see any difference between the images, but, when she was asked which house she would want to occupy, she almost always chose the one that was not on fire. “This is more complex than blindsight, because it means that the patient was unconsciously able to interpret and understand the symbolic meaning of the pictures,” Naccache said. “It is a powerful experiment to demonstrate that unconscious perception and unconscious cognition can reach upper levels of the brain.”
The article then goes on to discuss Naccache’s theories and here I can see parallels to both Greenfield’s (sustained representation) and Koch’s views (focus on content, an ‘ignition’ and networks).
“When we are conscious, the key property is our ability to report to ourselves or to others the content of the representation—as when I say, for example, ‘I am perceiving a flower,’ or the fact that I am conscious of speaking with you now on the telephone,” Naccache told me. “You have patients who are conscious, or who are able to make reports, but you can prove that some stimuli escaped their conscious reports, as in the case of blindsight or neglect. You can study the neural fate of these representations by showing that, even if the stimuli were not reported by the subject, they were still processed in the brain.”
Naccache believes that consciousness also requires an ability to sustain a representation over time, which Owen’s patient clearly was able to do. “In assessing apparently vegetative patients who are unable to speak, and thus report, the direction of research should be to look for sustained representation,” he said. “If we can prove by neuroimaging techniques that this person is able to actively maintain a given representation during tens of seconds, it provides strong evidence of conscious processing.”
Naccache has recently incorporated a third neurological feature into his definition of consciousness: broadcasting. In a person who is conscious, he explained, information entering the brain is processed in a few areas and then distributed—or broadcast—to many others. “It’s as though there is a kind of ignition in the brain, and then information is made available to a very rich number of regions,” Naccache told me. “And that makes sense, that the information is initially represented locally and then made available to a vast network, because the person has this ability to maintain the representation within the network for a long time.
The article also covers Giacino’s work that supports more of Greenfields views with consciousness dependent on levels of arousal (which may map to the quantity of neuronal assemblies of Susan).
The woman had what Giacino calls a “drive disorder,” in which a patient is unable to speak, move, or, possibly, think unless physically stimulated—by touch. Doctors believe that such disorders are caused by damage to the limbic lobes or to other parts of the brain that trigger and sustain behavioral responses. Some patients with drive disorders respond to drugs that increase brain levels of dopamine, a neurotransmitter that is associated with arousal. “Imagine if the woman were in a nursing home,” Giacino said. “Somebody would stop by for three minutes, check her bedpan, and present simple commands like ‘Squeeze my hand,’ ‘Close your eyes,’ and ‘Open your mouth.’ She is not going to do any of those things, but she clearly had a significant amount of preserved function. It had to be harnessed externally.” At J.F.K. Johnson, patients with drive disorders receive behavioral and drug therapy. (Some patients improve, but prospects for recovery are largely determined by the extent and nature of the damage to the drive system.)
Giacino applied Deep brain stimulation to one such patient and got spectacular results.
The researchers speculated that, because of damage to the man’s frontal lobe, thalamus, and brain stem—areas involved in regulating arousal—the nerve signals in his brain were muted. As Nicholas Schiff, a neurologist at Weill Cornell Medical College who led the study of the man’s brain, put it, “It’s as if a radio were turned to such a low volume that you couldn’t hear the music distinctly.” He added, “The scans confirmed our expectation that this patient had a greater capacity for language than he demonstrated.”
The researchers described implanting electrodes in the man’s thalamus, which, by stimulating the brain tissue, had enabled him to regain considerable physical and mental function. “Deep brain stimulation can promote significant late functional recovery from severe traumatic brain injury,” they wrote. When the electrodes were turned on in the man’s thalamus, his speech improved, his movements became more fluid, and he was able to chew and swallow. When the researchers turned off the electrical stimulation, the man soon relapsed.
This is close to associating arousal with a minimum quantity to synchronous firing of neuronal assemblies; but what I most like is the ignition analogy of Naccache.
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