14 December 2007

Belief, Disbelief, and Uncertainty: How the Brain Makes Us What

We are what our brains make us. What we believe, what we disbelieve. The UCLA Brain Mapping Center is using fMRI to map the different parts of the brain that perform different functions of making us what we are.
“These results suggest that the differences among belief, disbelief, and uncertainty may 1 day be distinguished reliably, in real time, by techniques of neuroimaging,” the researchers, with first author Sam Harris, a graduate student from the University of California, Los Angeles (UCLA) Brain Mapping Center, conclude. “This would have obvious implications for the detection of deception, for the control of the placebo effect during the process of drug design, and for the study of any higher-cognitive phenomenon in which the differences among belief, disbelief, and uncertainty might be a relevant variable.”

The study appeared online December 10 in advance of publication in the January 2008 issue of the Annals of Neurology....The difference between believing and disbelieving a proposition is 1 of the most potent regulators of human behavior and emotion, the authors write. “When one accepts a statement as true, it becomes the basis for further thought and action; rejected as false, it remains a string of words.”

...When they contrasted the trials of belief vs disbelief, they found increased signals in the ventromedial prefrontal cortex (VMPFC), which is involved in linking factual knowledge with emotion. “The involvement of the VMPFC in belief processing suggests an anatomical link between the purely cognitive aspects of belief and human emotion and reward,” they write....Contrasting disbelief with belief showed increased signals in the anterior insula, a brain region involved in the sensation of taste, perception of pain, and the feeling of disgust, the authors write. “Our results appear to make sense of the emotional tone of disbelief, placing it on a continuum with other modes of stimulus appraisal and rejection,” the authors write.

Finally, uncertainty evoked a positive signal in the anterior cingulate cortex and a decreased signal in the caudate, a region of the basal ganglia that plays a role in motor action, they note. Because both belief and disbelief were associated with an increased signal in the caudate compared with uncertainty, the authors suggest that the basal ganglia may play a role in mediating the cognitive and behavioral differences between decision and indecision.

The regions of the brain mediating belief also mediate emotion. Can anyone who has witnessed an online flame war doubt the connection? What about a family fight over Christmas dinner over whether a certain politician is Hitler reincarnated? Or a religious argument over which is the true faith? Emotion, belief, emotion--plus the caudate, preparation for motor action and memory encoding if necessary.

A person's entire life hinges on what he believes, whom she trusts, what groups they will join, what alliances they will make, what political party, what religion, what peer group . . . A lot depends upon a moment's hunch. Maybe, eventually, we can change our minds. But by then, what damage has been done?

Logic is an evolutionary latecomer to the human brain. For most people, logic is more difficult than cursory, emotional evaluation of an argument or situation. This is true for scientists, physicians, judges, and politicians--like anyone else. Trusting someone else's "judgment" is always a gamble. Of course, one who has never learned to use logic himself, has no other choice but to gamble on rapid, emotional evaluation.

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“During times of universal deceit, telling the truth becomes a revolutionary act” _George Orwell

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