
Originally Posted by
rodsky
Fear is an emotional response to a threat. It is a basic survival mechanism occurring in response to a specific stimulus, such as pain or the threat of danger. Some psychologists such as John B. Watson, Robert Plutchik, and Paul Ekman have suggested that fear is one of a small set of basic or innate emotions. This set also includes such emotions as joy, sadness, and anger. Fear should be distinguished from the related emotional state of anxiety, which typically occurs without any external threat. Additionally, fear is related to the specific behaviors of escape and avoidance, whereas anxiety is the result of threats which are perceived to be uncontrollable or unavoidable. Worth noting is that fear always relates to future events, such as worsening of a situation, or continuation of a situation that is unacceptable.
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Neurobiology
The amygdala is a key brain structure in the neurobiology of fear. It is involved in the processing of negative emotions (such as fear and anger). Researchers have observed hyperactivity in the amygdala when patients who were shown threatening faces or confronted with frightening situations. Patients with a more severe social phobia showed a correlation with increased response in the amygdala. Studies have also shown that subjects exposed to images of frightened faces, or faces of people from another race, exhibit increased activity in the amygdala.
The fear response generated by the amygdala can be mitigated by another brain region known as the rostral anterior cingulate cortex, located in the frontal lobe. In a 2006 study at Columbia University, researchers observed that test subjects experienced less activity in the amygdala when they consciously perceived fearful stimuli than when they unconsciously perceived fearful stimuli. In the former case, they discovered the rostral anterior cingulate cortex activates to dampen activity in amygdala, granting the subjects a degree of emotional control.
The role of the amygdala in the processing of fear-related stimuli has been questioned by research upon those in which it is b1lateral damaged. Even in the absence of their amygdala, they still react rapidly to fearful faces.
Suppression of amygdala activity can also be achieved by pathogens. Rats infected with the toxoplasmosis parasite become less fearful of cats, sometimes even seeking out their urine-marked areas. This behavior often leads to them being eaten by cats. The parasite then reproduces within the body of the cat. There is evidence that the parasite concentrates itself in the amygdala of infected rats.
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Further reading
* Bourke, Joanna, Fear: a cultural history, Virago (2005)
* Robin, Corey, Fear: the history of a political idea, Oxford University Press (2004)
* Duenwald, Mary. The Physiology of ... Facial Expressions, Discover magazine, v.26, n.1, January 2005
* Gardner, Dan, Risk: The Science and Politics of Fear, Random House, Inc., 2008. ISBN 0771032994
* Krishnamurti, Jiddu, On Fear, Harper Collins, ISBN 0-06-251014-2 (1995)
-RODION