Personality is a broad term that describes how people usually relates to the world and your inner self. After the period of development through childhood and adolescence, these patterns reasonably stable relationship for life. One speaks of traits and influence behavior, thought, motivation and emotion.
Since everyone is different in their own way, psychologists have debated how to characterize the personality. The most popular approach has been so far using five dimensions: openness to experience (curious or cautious), conscientiousness (organized or inadvertently), (outgoing or lonely) extraversion, agreeableness (friendly or individual) and neuroticism ( nervous or insurance).
A self-report questionnaire is often used to give a score to each dimension, then someone’s personality is described. These descriptions have been used to understand the normal and abnormal behavior, and to predict the success of work, academic performance and interpersonal relationships.
Both genetic and environmental factors that determine someone’s personality. Genes account for between 30-50% of the determination and the rest consists largely of the unique environmental experience for the individual.
Understanding the neurophysiology of personality sometimes is seen as the holy grail of psychology Santo, and was the subject of the first article of Sigmund Freud, Project for a scientific psychology in 1895.
Early developments in this field come from the descriptions of historical cases.
The classic case of Phineas Gage (1823-1860), American railroad worker who had a large iron bar completely driven through the head in an accident, which destroyed most of his left frontal lobe and It resulted in a profound personality change.
After the accident, Gage was described as being made “irregular, irreverent, indulging at times in the grossest profanity (which was not previously his custom), manifesting … little deference for his fellows, impatient of restraint or advice when it conflicts with his desires. ”
From this case, the frontal lobes, which occupy the third frontal part of the brain, emerged as the most functionssuch seat as judgment, motivation, regulation of behavior and social consciousness.
Later, in the early 20th century, neuroanatomists identified the limbic lobe – a piece shaped arch of the parietal lobes frontal, temporal and located in the center of the brain – as the seat of emotions. He was recognized as an important contribution to personality.
As evolved our understanding, personality has been considered as a compound of character and temperament.
temperament is understood as the way the body produces behavior. It refers to certain biases that an individual has the time to respond to external stimuli.
A well established model proposes that while personality traits are based on normal behavior, temperamental traits are predispositions of a person when it comes to four areas: harm avoidance, novelty seeking, reward dependence , and persistence. These are closely related to basic emotions like fear, anger, attachment and ambition.
High-avoidance of damage leads to avoid behaviors that produce no reward or punishment cause; as in people who are shy, insecure or socially inhibited.
Individuals with such traits have increased activity in the brain’s fear circuitry, the involvement of the amygdala and other structures of the limbic lobe.
This activity has been linked to abnormalities in two neurotransmitters :. And γ-amino serotonin acid (GABA) butyric acid. Modulation of these drugs – such as inhibitors of serotonin reuptake inhibitors (SSRIs include Prozac that) and benzodiazepines, including Valium – can help people with depression, anxiety and obsessive thoughts
novelty seeking leads to exploration and individuals high in this trait are curious, quick-tempered, impulsive and easily bored. They have increased activity in the basal ganglia, which are groups of neurons that sit in the middle of the brain. This feature has also been linked with pleasure molecule called dopamine, which acts on the basal ganglia, and changes in this way are associated with novelty seeking in different ways.
People with high reward dependence and seeking social rewards are likely to be socially sensitive and dependent on social approval. Those low on this trait are-tough, cold and distant.
The temporal lobes of the brain play an important role in how we process social cues, and increased activity in the anterior part of these lobes and in a brain structure called the thalamus has been linked to a higher level reward dependence.
Persistence leads to maintaining behavior despite fatigue, repetitiveness and frustration, and often results in qualities such as industriousness and determination. Particular brain regions important for this include the inner and lower parts of the frontal lobes, especially those called the anterior cingulate cortex and orbitofrontal cortex, and networks involving the basal ganglia.
Persistence is little related to motivation. Emotion plays an important role in maintaining this unit, such as basic emotions like happiness, tend to energize behavior and lack of emotion it has the opposite effect.
Researchers have attempted to examine whether the brains of people who reach high temperatures, such as Einstein, are different. Although there have been reports that the brain regions involved in numeric and spatial skills (mid-frontal and parietal regions below) were larger and the fiber bundle connecting the two halves of the brain (corpus callosum) was thicker, not there is consensus that Einstein’s brain was remarkably different from others.
There is, however, considerable evidence that people with higher intelligence, as measured by psychometric tests, have larger brains on average. Geniuses whose brains have been studied and found to include great Carl Gauss (mathematician), Rudolf Wagner (composer) and Vladimir Lenin (political leader), although there are many exceptions to this rule.
Character involves goals and values of an individual in relation to oneself and others. It is the conceptual core of the personality complex and involves higher functions such as reasoning, abstraction, concept formation and interpretation of symbols.
A network affects the frontal, temporal and parietal is important for these functions, reasoning and abstraction still functions great lobe front, the symbolic representation served by the lobes and the formation of new memories provided by the hippocampus and the temporal and parietal network memory.
The interaction of these networks with regions that regulate emotion temperament and leads to the appearance of individual personality. Importantly, no particular personality trait comes from a specific region of the brain, how the brain works as a complex network.
There is also considerable redundancy in these networks because they have an innate ability to compensate, sometimes known as neuroplasticity. An excellent example of neuroplasticity was demonstrated in London taxi drivers have been shown to increase gray matter in the back of their hippocampus – related to the spatial representation of the environment -., Compared to those who do not were professional drivers
The neuroplasticity is central to the recovery from brain injury, such as after a stroke, when other parts of the brain take over some of the functions of the damaged regions.
it is not uncommon for a problem in brain development or failure of adaptive mechanisms leading to the development of personality disorder. This is when a person has a persistent pattern of behavior and ways of thinking that deviates from social and cultural norms, which causes distress.
Researchers have begun to look to the neurological biology of various personality disorders. A topic of interest has been the multiple personality disorder, which is now known as dissociative identity disorder. Have been reported people who suffer from this have reduced volumes hippocampus and amygdala and reduced activity orbitofrontal cortex. These have been linked to childhood trauma that results in abnormal regulation of emotion.
Although we have come a long way since the days of phrenology, when the personality sense of blows to the head reads, neurological biology of normal and abnormal aspects of personality is only starting to be understood. What is clear, however, is that personality comes from a complex neuronal construction, formed by genetics and early developmental experiences influence the structure and function of the brain.
Author: Perminder Sachdev, Scientia Professor of Neuropsychiatry, Center Healthy Aging Brain (cheba) School of Psychiatry at UNSW Australia
Courtesy: The Conversation