Brain And Personality Development
Linking how brain structure is related to basic personality traits is a crucial step to improving our understanding of the link between the brain morphology and particular mood, cognitive, or behavioural disorders
Brain and Personality Development
The researchers found that high levels of neuroticism, which may predispose people to develop neuropsychiatric disorders, were associated with increased thickness as well as reduced area and folding in some regions of the cortex such as the prefrontal-temporal cortices at the front of the brain.
In contrast, openness, which is a personality trait linked with curiosity, creativity and a preference for variety and novelty, was associated with the opposite pattern, reduced thickness and an increase in area and folding in some prefrontal cortices.
The volunteers whose brains were imaged as part of the Human Connectome Project were all healthy individuals aged between 22 and 36 years with no history of neuro-psychiatric or other major medical problems. However, the relationship between differences in brain structure and personality traits in these people suggests that the differences may be even more pronounced in people who are more likely to experience neuro-psychiatric illnesses.
This is not the first time the researchers have found links between our brain structure and behaviour. A study published by the group last year found that the brains of teenagers with serious antisocial behaviour problems differ significantly in structure to those of their peers.
Since everyone is different in their own way, psychologists have debated how to characterise personality. The most popular approach has so far been to use five dimensions: openness to experience (curious or cautious), conscientiousness (organised or careless), extraversion (outgoing or solitary), agreeableness (friendly or detached) and neuroticism (nervous or secure).
A self-report questionnaire is often used to give a score to each dimension, which then describes someone's personality. These descriptions have been used to understand normal and abnormal behaviour, and to predict work success, academic achievement and interpersonal relationships.
Both genetic and environmental factors determine someone's personality. Genes account for between 30-50% of the determination and the rest is made up largely of environmental experiences unique to the individual.
Understanding the neurological physiology of personality is sometimes seen as the holy grail of psychology, and was the topic of Sigmund Freud's first paper, Project for a Scientific Psychology, in 1895.
The classical case is of Phineas Gage (1823-60), an American railroad worker who had a large iron rod driven completely through his head in an accident, which destroyed most of his left frontal lobe and resulted in a profound personality change.
A well-established model proposes that whereas personality traits are based on habitual behaviour, temperamental traits are someone's predispositions when it comes to four areas: harm avoidance, novelty seeking, reward dependence, and persistence. These are closely related to basic emotions such as fear, anger, attachment and ambition.
Novelty seeking leads to exploration and individuals high on this trait are curious, quick-tempered, impulsive and easily bored. They have increased activity in the basal ganglia, which are clumps of neurons sitting in the middle of the brain. This trait has also been linked to the so-called pleasure molecule dopamine, which acts on the basal ganglia, and changes in this pathway are associated with seeking novelty in different ways.
The temporal lobes of the brain play a major 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 related to higher levels of reward dependence.
Persistence leads to the maintenance of a behaviour despite fatigue, repetitiveness and frustration, and often results in such qualities as industriousness and determination. The regions of the brain particularly important for this include the inner and lower parts of the frontal lobes, especially those called the anterior cingulate and the orbitofrontal cortex, and their networks that involve the basal ganglia.
Researchers have attempted to examine whether brains of high achieving people, such as Einstein, are different. While there have been reports that brain regions involved in numerical and spatial abilities (mid-frontal and inferior parietal regions) were larger and the bundle of fibres connecting the two halves of the brain (corpus callosum) was thicker, there is no consensus that Einstein's brain was remarkably different from others.
There is, however, considerable evidence that people with higher intelligence, as measured on psychometric tests, have larger brains on the average. Geniuses whose brains have been studied and found to be large include Carl Gauss (mathematician), Rudolf Wagner (composer) and Vladimir Lenin (political leader), although there are also many exceptions to this rule.
Character involves an individual's goals and values in relation to oneself and others. It is the conceptual core of personality and involves complex higher functions such as reasoning, abstraction, concept formation and interpretation of symbols.
Interaction of these networks with regions regulating temperament and emotion leads to the emergence of individual personality. It is important to emphasise that no particular personality characteristic comes from a specific brain region, as the brain operates as a complex network.
Not uncommonly, a problem in brain development or the failure of adaptive mechanisms leads to the development of personality disorder. This is when a person has an enduring pattern of behaviour and ways of thinking that deviates from social and cultural norms, causing distress.
Researchers have begun to look at the neurological biology of various personality disorders. One subject of interest has been multiple personality disorder, now referred to as dissociative identity disorder. People suffering from this have been reported to have reduced volumes of the hippocampus and amygdala and reduced activity of the orbitofrontal cortex. These have been linked to childhood trauma which results in abnormal regulation of emotion.
While we have come a long way from the days of phrenology, when personality was read by feeling bumps on the head, the neurological biology of normal and abnormal aspects of personality is only beginning to be understood. What is clear though, is that personality comes from a complex neural construct, shaped by genetics and early developmental experiences that influence the structure and function of the brain. Source:The Conversation This article was originally published on The Conversation. Read the original article.
I led the international team of researchers behind the study, published in Social Cognitive and Affective Neuroscience. We analysed the brains of over 500 healthy people aged 22 to 36 years. The structural brain scans were provided by the Human Connectome Project, a US project funded by the National Institutes of Health.
This is the first time the big five personality traits have been clearly linked to differences in brain thickness, area and folding in a large sample of healthy individuals. However we have previously found that the brains of teenagers with serious antisocial behavioural problems differ significantly in structure to those of their peers who do not display such disruptive behaviour.
The relation between differences in brain structure and personality in healthy people suggests that brain changes may be even more pronounced in people with mental illnesses. Linking the brain structure to basic personality traits is a crucial step to improving our understanding of mental disorders. In the future, it may even give us the opportunity to detect those who are at high risk of developing mental illnesses early, which has obvious implications for prompt intervention.
The new study suggests that personality is strongly rooted in core principles that govern brain evolution. Indeed, cortical stretching is a key evolutionary process that has enabled the human brain to grow rapidly while still fitting into the skull.
The fact that there are such pronounced differences in brain structure between people with different personality types suggests personality is at least partly genetic. However, brain scans alone cannot get to the bottom of the causes of differences in personality. The next step will be to run studies that follow up people from young ages, to understand how their genes and the environment they are brought up in affect their brain maturation and personality.
The predominant approach to dimensionalizing personality traits ,  assesses five domains: Neuroticism, Extraversion, Openness to Experience, Agreeableness and Conscientiousness , . Studies of the neurobiological substrates of personality traits have largely focused on the most long-standing domains: Neuroticism and Extraversion , . The unevenness of coverage of the five principal personality domains is partly ascribable to the constraints inherent in task-based imaging approaches, which require effective cognitive, behavioral or emotional probes that target specific psychological constructs. Consequentially, task-based studies are limited in the breadth of neural systems and cognitive-behavioral constructs that can be effectively probed in a given experiment. Investigating the relationship between personality and brain structure is one method for simultaneously delineating brain systems potentially relevant to all five trait domains , but interpretations of structure-behavior relationships remain ambiguous.
Psychologists have worked out that all personality traits can be divided into five factors, commonly called the Big Five: conscientiousness, extraversion, neuroticism, agreeableness, and openness/intellect. Colin DeYoung at the University of Minnesota and colleagues wanted to know if these personality factors correlated with the size of structures in the brain. 041b061a72