̽��ֱ�� of Cambridge - Luca Passamonti

Personality traits linked to differences in brain structure

cjb250 — Wed, 25 Jan 2017 00:01:16 +0000

According to psychologists, the extraordinary variety of human personality can be broken down into the so-called ‘Big Five’ personality traits, namely neuroticism (how moody a person is), extraversion (how enthusiastic a person is), openness (how open-minded a person is), agreeableness (a measure of altruism), and conscientiousness (a measure of self-control).

In a study published today in the journal Social Cognitive and Affective Neuroscience, an international team of researchers from the UK, US, and Italy have analysed a brain imaging dataset from over 500 individuals that has been made publicly available by the Human Connectome Project, a major US initiative funded by the National Institutes of Health. In particular, the researchers looked at differences in the brain cortical anatomy (the structure of the outer layer of the brain) as indexed by three measures – the thickness, area, and amount of folding in the cortex – and how these measures related to the Big Five personality traits.

“Evolution has shaped our brain anatomy in a way that maximizes its area and folding at the expense of reduced thickness of the cortex,” explains Dr Luca Passamonti from the Department of Clinical Neurosciences at the ̽��ֱ�� of Cambridge. “It’s like stretching and folding a rubber sheet – this increases the surface area, but at the same time the sheet itself becomes thinner. We refer to this as the ‘cortical stretching hypothesis’.”

“Cortical stretching is a key evolutionary mechanism that enabled human brains to expand rapidly while still fitting into our skulls, which grew at a slower rate than the brain,” adds Professor Antonio Terracciano from the Department of Geriatrics at the Florida State ̽��ֱ��. “Interestingly, this same process occurs as we develop and grow in the womb and throughout childhood, adolescence, and into adulthood: the thickness of the cortex tends to decrease while the area and folding increase.”

In addition, as we get older, neuroticism goes down – we become better at handling emotions. At the same time, conscientiousness and agreeableness go up – we become progressively more responsible and less antagonistic.

̽��ֱ��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.

“Our work supports the notion that personality is, to some degree, associated with brain maturation, a developmental process that is strongly influenced by genetic factors,” says Dr Roberta Riccelli from Italy.

“Of course, we are continually shaped by our experiences and environment, but the fact that we see clear differences in brain structure which are linked with differences in personality traits suggests that there will almost certainly be an element of genetics involved,” says Professor Nicola Toschi from the ̽��ֱ�� ‘Tor Vergata’ in Rome. “This is also in keeping with the notion that differences in personality traits can be detected early on during development, for example in toddlers or infants.”

̽��ֱ��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.

“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,” adds Dr Passamonti. “We also need to have a better understanding of the relation between brain structure and function in healthy people to figure out what is different in people with neuropsychiatric disorders.”

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.

Reference
Riccelli, R et al. Surface-based morphometry reveals the neuroanatomical basis of the five-factor model. Social Cognitive and Affective Neuroscience; 25 Jan 2016; DOI: 10.1093/scan/nsw175

Our personality may be shaped by how our brain works, but in fact the shape of our brain can itself provide surprising clues about how we behave – and our risk of developing mental health disorders – suggests a study published today.

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

Luca Passamonti

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Drain Brain Spider

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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‘Map’ of teenage brain provides strong evidence of link between serious antisocial behaviour and brain development

cjb250 — Wed, 15 Jun 2016 23:01:00 +0000

In a study published today in the Journal of Child Psychology and Psychiatry, researchers used magnetic resonance imaging (MRI) methods to look at the brain structure of male adolescents and young adults who had been diagnosed with conduct disorder – persistent behavioural problems including aggressive and destructive behaviour, lying and stealing, and for older children, weapon use or staying out all night.

In particular, the researchers looked at the coordinated development of different brain regions by studying whether they were similar or different in terms of thickness. Regions that develop at similar rates would be expected to show similar patterns of cortical thickness, for example.

“There’s evidence already of differences in the brains of individuals with serious behavioural problems, but this is often simplistic and only focused on regions such as the amygdala, which we know is important for emotional behaviour,” explains Dr Luca Passamonti from the Department of Clinical Neurosciences at the ̽��ֱ�� of Cambridge. “But conduct disorder is a complex behavioural disorder, so likewise we would expect the changes to be more complex in nature and to potentially involve other brain regions.”

In a study funded by the Wellcome Trust and the Medical Research Council, researchers at the ̽��ֱ�� of Cambridge recruited 58 male adolescents and young adults with conduct disorder and 25 typically-developing controls, all aged between 16 and 21 years. ̽��ֱ��researchers divided the individuals with conduct disorder according to whether they displayed childhood-onset conduct disorder or adolescent-onset conduct disorder.

̽��ֱ��team found that youths with childhood-onset conduct disorder (sometimes termed ‘early-starters’) showed a strikingly higher number of significant correlations in thickness between regions relative to the controls. They believe this may reflect disruptions in the normal pattern of brain development in childhood or adolescence.

On the other hand, youths with adolescent-onset conduct disorder (‘late starters’) displayed fewer such correlations than the healthy individuals. ̽��ֱ��researchers believe this may reflect specific disruptions in the development of the brain during adolescence, for example to the ‘pruning’ of nerve cells or the connections (synapses) between them.

As the findings were particularly striking, the researchers sought to replicate their findings in an independent sample of 37 individuals with conduct disorder and 32 healthy controls, all male and aged 13-18 years, recruited at the ̽��ֱ�� of Southampton; they were able to confirm their findings, adding to the robustness of the study.

“ ̽��ֱ��differences that we see between healthy teenagers and those with both forms of conduct disorders show that most of the brain is involved, but particularly the frontal and temporal regions of the brain,” says Dr Graeme Fairchild, who is an Associate Professor in the Department of Psychology at the ̽��ֱ�� of Southampton. “This provides extremely compelling evidence that conduct disorder is a real psychiatric disorder and not, as some experts maintain, just an exaggerated form of teenage rebellion.

“These findings also show that there are important differences in the brain between those who develop problems early in childhood compared with those who only show behavioural problems in their teenage years. More research is now needed to investigate how to use these results to help these young people clinically and to examine the factors leading to this abnormal pattern of brain development, such as exposure to early adversity.”

“There’s never been any doubt that conditions such as Alzheimer’s disease are diseases of the brain because imaging allows us to see clearly how it eats away at the brain,” adds Professor Nicola Toschi from the ̽��ֱ�� “Tor Vergata” of Rome, “but until now we haven’t been able to see the clear – and widespread – structural differences in the brains of youths with conduct disorder.”

Although the findings point to the importance of the brain in explaining the development of conduct disorder, it is not clear how the structural differences arise and whether, for example, it is a mixture of an individual’s genetic make-up and the environment in which they are raised that causes the changes. However, the researchers say their findings may make it possible to monitor objectively the effectiveness of interventions.

“Now that we have a way of imaging the whole brain and providing a ‘map’ of conduct disorder, we may in future be able to see whether the changes we have observed in this study are reversible if early interventions or psychological therapies are provided,” says Professor Ian Goodyer from the Department of Psychiatry at the ̽��ֱ�� of Cambridge.

Reference
Fairchild, G et al. Mapping the structural organization of the brain in conduct disorder: replication of findings in two independent samples. Journal of Child Psychology and Psychiatry; 16 June 2016 DOI: 10.1111/jcpp.12581

̽��ֱ��brains of teenagers with serious antisocial behaviour problems differ significantly in structure to those of their peers, providing the clearest evidence to date that their behaviour stems from changes in brain development in early life, according to new research led by the ̽��ֱ�� of Cambridge and the ̽��ֱ�� of Southampton, in collaboration with the ̽��ֱ�� of Rome “Tor Vergata” in Italy.

Conduct disorder is a complex behavioural disorder, so we would expect the changes to be more complex in nature and to potentially involve other brain regions.

Luca Passamonti

Nicola Toschi

̽��ֱ��orbitofrontal cortex (blue) and medial temporal cortex (red) were more similar in terms of thickness in youths with Conduct Disorder than in typically-developing youths, suggesting that the normal pattern of brain development is disrupted.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. For image use please see separate credits above.

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