Personality: a Neurobiological Model of Extraversion Essay

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Personality: a Neurobiological Model of Extraversion

Underlying the question of whether brain equals behavior is the possibility that one's personality may be understood on a neurobiological level. Personality affects how a person will behave in certain situations. Peoples' attitudes towards their environments, their dispositions, personal preferences and dislikes all help determine their everyday actions. If behavior is controlled by the nervous system, these factors which make up a person's personality must also fall under its direction. This does not refer to whether one's personality is a result of environment or genomic make-up. It has already been proposed that personality is 50%-70% hereditary and that home environment has
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Recently Richard Depue (4) has developed the model further, proposing that extraversion is not a change in overall arousal level. Rather it is a motivated behavior; extraverts demonstrate an increased sensitivity to reward signals (incentive motivated behavior.) They seek social dominance and achievement, and react accordingly in social situations. According to Depue there are three criterion necessary to establish the neurobiological basis of such a personality: a) define the network of neural structures associated with the trait, b) explain how individual differences occur within the functioning of that network and c) identify the sources of individual differences. Using an animal model Depue found that the ventral tegmental area dopamine projection system facilitates incentive motivated behavior in rats. Dopamine agonists and antagonists in the ventral tegmental area facilitate and impair respectively exploratory, aggressive, social and sexual behavior. Similar phenomena is observed in humans-- dopamine activating drugs tend to stimulate an enhanced interaction with the environment. Individual differences in dopamine levels, as expected with extraversion, can result both genetically and environmentally. Different strains of inbred mice display differing dopamine and extraversion levels. While this supports the genetic explanation for individual personality differences, experience also plays a role. Ventral tegmental

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