Health knowledge made personal
Join this community!
› Share page:
Search posts:

What fear looks like, part 3.

Posted Oct 22 2008 6:15pm

Another in a series of posts featuring images that somehow depict panic and anxiety. These are photos that can set my heart to racing before I've consciously realized what I'm looking at. Seriously.*

See any common themes?

* From an an article about neuroscientist Joseph LeDoux:

"Over the last decade or so, LeDoux and others have worked out this circuitry in lab rats step by step, each accreted detail sending a small ripple through the world of human psychology. His laboratory has been able to show that as soon as conditioned animals hear the tone that precedes a shock, the auditory information travels to a way station in the brain known as the sensory thalmus, an essential stop for any incoming information about the world, and then immediately continues on to the amygdala. In rats, a fear-inducing sound goes from the ear to the amygdala in 12 milliseconds - that is, 12 one-thousands of a second. Moreover, LeDoux says, cells in this corner of the amygdala, known as the lateral nucleus,"learn" and memorize the fearful stimulus with incredible rapidity and tenacity. The research suggests that all it takes is one terrifying experience to form a lifelong emotional memory, one that is extremely difficult to erase.

"While LeDoux's lab has concentrated on this downstairs circuit, the laboratory of Michael Davis, now at Emory University in Atlanta after 29 years at Yale, has sketched out what might be considered the high road in the processing of fear, one that may more closely mirror the routine processing of fearful information in humans. It passes from the sensory organs, like eyes and ears, and lingers in the cortex, where conscious memories are formed, before threading down to the amygdala. Davis has also tentatively identified a separate destination, called the bed nucleus of the stria terminalis, which is heavily connected to the amygdala and seems to control chronic states of fear like anxiety and worry.

"This may sound like a lot of dense neural cartography, but the significance for psychiatry, if the same dual circuitry pertains to humans, would be profound. It suggests that because there are two different neural routes to the amygdala, two different kinds of fear-related memory can form. Indeed, one of the provocative things about LeDoux's circuit is where it doesn't go. It doesn't go to the thinking part of the brain first. And what that implies - certainly in rats, and almost certainly in humans ... is that we experience, learn and unconsciously commit to emotional memory many fearful situations, without ever being aware of what has triggered the racing heart and quick pulse.

"One hallmark of a panic attack, for example, is that its victim cannot understand what has triggered such a powerful reaction. The implication of fear-conditioning experiments in animals is that we have a separate memory of a fearful stimulus, be it a bear or a dinner party, lodged in the amygdala, probably informed by things we have heard or seen but do not consciously remember. So it's as if we walk through the world half-blind, bumping into archival stimuli, things we never knew scared us, things that we can't consciously remember but that nevertheless set in motion inexplicable and disturbing sensations of dread. Freudian analysts who have followed the work of LeDoux and others have been quick to point out that neuroscience's version of unconscious fear, in the words of Dr. Jean Roiphe, a Manhattan analyst, "strongly corresponds with the Freudian notion that it's indelible and never goes away."

(Italics are mine.)


Post a comment
Write a comment:

Related Searches