社交性に関連する脳部位

画像 人がどれほど社交的であるかを決定するかもしれない脳部位を突き止めたと言う。暖かく感傷的な人は、目の直上の脳皮質と脳中心部の脳組織が大きい傾向がある。ケンブリッジ大の専門家は、チョコレートや性を楽しむことを可能にするのと同じ部位であるという。
 自閉症や統合失調症など社会的交流が問題となる精神疾患に新たな視点をもたらす可能性がある。
 41人の健康男性ボランティアの脳スキャンを実行した。感情の暖かさと社会性のスコアの高い人は、眼窩前頭皮質と腹側線状体という灰白質の2つの部分が大きかった。
 生まれつきのものなのか、個人的な経験を通して発達したのかは不明である。
喜びの領域
 褒められると線状体が活性化し、魅力的な顔や微笑みにより眼窩前頭皮質が活性化されるということがすでにわかっている。
 社会性や感情の暖かさは私達の個性の非常に複雑な機能である。
 人が特性を表現する程度の差が生物学的レベルで理解される手助けになるかもしれない。社会的な交流に価値を見出す程度が、食事や甘いものや性といった単純な生物学的駆動に重要な脳部分に関連していることが興味深い。
 打ち解けて交際することが本質的な報酬であると連想させる。自閉症のような臨床疾患の理解に役立つ可能性もある。
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Page last updated at 06:34 GMT, Wednesday, 20 May 2009 07:34 UK
'People-person' brain area found
http://news.bbc.co.uk/2/hi/health/8055296.stm

Brain MRI
The researchers noted differences in two brain regions

Scientists say they have located the brain areas that may determine how sociable a person is.

Warm, sentimental people tend to have more brain tissue in the outer strip of the brain just above the eyes and in a structure deep in the brain's centre.
These are the same zones that allow us to enjoy chocolate and sex, the Cambridge University experts report in the European Journal of Neuroscience.
The work suggests that some people may get a similar buzz from being sociable.
It could also lead to new insights into psychiatric disorders where difficulties in social interaction are prominent, such as autism or schizophrenia.

For some people, socializing is an intrinsic reward, just like chocolate or cannabis
Professor Simon Baron Cohen, of the Autism Research Centre in Cambridge
The brain scan study was carried out on 41 healthy male volunteers.
The men who scored higher on questionnaire-based ratings of emotional warmth and sociability had more grey matter in two brain areas - the orbitofrontal cortex and ventral striatum.
The researchers say it is not clear whether the men were born with these brain differences or whether the brain regions in question grew in response to personal experiences.

Pleasure zones
Experts already know that the striatum becomes activated by receiving compliments and the orbitofrontal cortex is activated by attractive faces and smiling.
Lead researcher Dr Graham Murray said: "Sociability and emotional warmth are very complex features of our personality.
"This research helps us understand at a biological level why people differ in the degrees to which we express those traits.
"It's interesting that the degree to which we find social interaction rewarding relates to the structure of our brains in regions that are important for very simple biological drives such as food, sweet liquids and sex.
"Perhaps this gives us a clue to how complex features like sentimentality and affection evolved from structures that in lower animals originally were only important for basic biological survival processes."
Professor Simon Baron Cohen, of the Autism Research Centre in Cambridge, said: "This is an important study in showing that the degree to which we find socializing rewarding is correlated with differences in brain structure.
"It reminds us that for some people, socializing is an intrinsic reward, just like chocolate or cannabis. And that what you find rewarding depends on differences in the brain.
"This research teaches us about individual differences in a typical sample, but has implications for our understanding of clinical conditions like autism, where socializing may be less rewarding."

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The brain structural disposition to social interaction
European Journal of Neuroscience
Published Online: May 11 2009 6:26AM
DOI: 10.1111/j.1460-9568.2009.06760.x

Mae"l Lebreton 1,2,3 , Anna Barnes 1,2,3 , Jouko Miettunen 4 , Leena Peltonen 5,6 , Khanum Ridler 1,7 , Juha Veijola 4 , Pa"ivikki Tanskanen 8 , John Suckling 1,2,3 , Marjo-Riitta Jarvelin 9,10 , Peter B. Jones 3 , Matti Isohanni 4 , Edward T. Bullmore 1,2,3 and Graham K. Murray 1,2,3
1 Brain Mapping Unit, University of Cambridge, Cambridge, UK
2 Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge, UK
3 Department of Psychiatry, University of Cambridge, Cambridge, UK
4 Department of Psychiatry, University of Oulu, Oulu, Finland
5 Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
6 Department of Medicinal Genetics, University of Helsinki, Helsinki, Finland
7 Clinical Imaging Centre, CPDM, GlaxoSmithKline, London, UK
8 Department of Radiology, University of Oulu, Oulu, Finland
9 Department of Public Health Science and General Practice, University of Oulu, Oulu, Finland
10 Department of Epidemiology and Public Health, Imperial College London, London, UK
Correspondence to Dr G. K. Murray, Brain Mapping Unit, Department of Psychiatry, University of Cambridge, Box 189 Addenbrooke's Hospital, Cambridge CB2 0QQ.
E-mail: gm285@cam.ac.uk
Copyright Journal compilation (c) 2009 Federation of European Neuroscience Societies and Blackwell Publishing Ltd
KEYWORDS
MRI . personality . reward dependence . temperament . ventral striatum
ABSTRACT

Social reward dependence (RD) in humans is a stable pattern of attitudes and behaviour hypothesized to represent a favourable disposition towards social relationships and attachment as a personality dimension. It has been theorized that this long-term disposition to openness is linked to the capacity to process primary reward. Using brain structure measures from magnetic resonance imaging, and a measure of RD from Cloninger's temperament and character inventory, a self-reported questionnaire, in 41 male subjects sampled from a general population birth cohort, we investigated the neuro-anatomical basis of social RD. We found that higher social RD in men was significantly associated with increased gray matter density in the orbitofrontal cortex, basal ganglia and temporal lobes, regions that have been previously shown to be involved in processing of primary rewards. These findings provide evidence for a brain structural disposition to social interaction, and that sensitivity to social reward shares a common neural basis with systems for processing primary reward information.

Received 6 August 2008, revised 14 April 2009, accepted 17 April 2009

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