The observable examined

no fear

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The feeling of fear – an “innate” biological response – is very important for the self-preservation of an animal. It is required to anticipate or remove oneself from potentially dangerous situations (Flight -one of the four behavioral Fs that are fundamental to any organism, the other three being Fight, Food and Sex) . Neuroscientists  have pinpointed the locus of the brain structure (bilateral) mediating the fear response, in macaques, to the amygdala.

While monkey brains are very similar to human brains,  until very recently, there was no conclusive proof that the amygdala in humans served the same function. Enter patient SM. She has bilateral lesions to the amygdala. And guess what, she has no feelings of fear!!  Listen to the NPR interview with the lead researcher Daniel Tranel . (Tranel makes an interesting distinction between fear and worry – immediate vs a longer term concern. Remember, human brains are fantastic simulation engines – more on this topic in another blog).

She understands the concept of fear intellectually but cannot experience it! As a consequence, she does not remove herself from harmful situations where most “normal” people would.

After I had learned about the monkey amygdala studies, I had made the leap of faith that this would explain the spectrum of human personalities, as captured by adjectives like,  fearless , extremely cautious, adventurous etc., (they briefly touch upon this in the interview). 

 The implication is that this personality trait is a function of the wiring in the specific brain structure (amygdala).  So it is inspite of  “you” not because of “you“.  However, cognitive override (pre-requisite is that the mediating brain structures are intact) can also be employed but is likely to be a function of the ability to rationalize the facts pertaining to the threatening situation.

This is likely a general principle in the brain. What I mean is, brain wiring as a process, follows some generic genetically prescribed rules. Since this process is not exact, most of the time, you will get “normal” brains albeit with enough variability to make us all a little different. Nature (neural plasticity) + Nurture (environmental influences) then dictactes the social and professional trajectories of our lives.

At times, the wiring process may become skewed – positively (more dense) or negatively (less dense).  Positive skew results in individuals we label  genuises, prodigy, talented,gifted, or pick your favorite label ( typically all attributed to a religious god).  This process is infrequent (fewer) hence the increased value of these individuals to society. The premium is higher if special abilities are spotted at a young age.      

When the process is negatively skewed,  we hear of the rain men of the world, idiot savants, individuals with extraordinary abilities in one modality but sorely lacking in others, predominantly in basic social skills.

Note that I am using density of brain wiring as a proxy, also, for the size of individual brain structures.


Written by asterix98

January 2, 2011 at 8:50 pm

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