Jul 22, 2010

Brain structure linked to personality

Sci­en­tists have found that the size of dif­fer­ent parts of peo­ple’s brains cor­re­spond to their per­son­al­i­ties. For ex­am­ple, con­sci­en­tious peo­ple tend to have a big­ger lat­er­al pre­fron­tal cor­tex, a brain re­gion in­volved in plan­ning and con­trol­ling act­ions.

Psy­chol­o­gists com­monly break down all per­son­al­ity traits in­to five fac­tors: con­sci­en­tiousness, ex­tra­ver­sion, neu­rot­i­cism, agree­a­ble­ness, and open­ness/in­tel­lect. Re­search­ers Col­in De­Young at the Uni­vers­ity of Min­ne­so­ta and col­leagues wanted to know if these fac­tors cor­re­lat­ed with the size of struc­tures in the brain.

The me­di­al or­bi­to­front­al cor­tex, whose act­iv­ity is high­light­ed in the brain scan ab­ove, was found to be sig­nif­i­cantly larg­er in very extro­verted peo­ple. (Im­age cour­tesy J. O'Doh­erty et al., Cal­tech)

The scientists gave 116 vol­un­teers a ques­tion­naire to de­scribe their per­son­al­ity, then gave them a brain im­ag­ing test that meas­ured the rel­a­tive size of dif­fer­ent parts of the brain. Sev­er­al links were found be­tween the size of cer­tain brain re­gions and per­son­al­ity. The re­search ap­pears in the jour­nal Psy­cho­log­i­cal Sci­ence.

For ex­am­ple, “ev­ery­body, I think, has a com­mon sense of what ex­tro­ver­sion is – some­one who is talk­a­tive, out­go­ing, brash,” said De­Young. “They get more pleas­ure out of things like so­cial in­ter­ac­tion, amuse­ment parks, or really just about an­y­thing, and they’re al­so more mo­ti­vat­ed to seek re­ward, which is part of why they’re more as­sertive.” That quest for re­ward is thought to be a lead­ing fac­tor in ex­tro­ver­sion.

Ear­li­er stud­ies had found parts of the brain that are ac­tive in con­sid­er­ing re­wards. So DeY­oung and his col­leagues rea­soned that those re­gions should be big­ger in ex­tro­verts. In­deed, they found that one of those re­gions, the me­di­al or­bi­to­front­al cor­tex – just above and be­hind the eyes – was sig­nif­i­cantly larg­er in very extro­verted study sub­jects.

The study found si­m­i­lar as­socia­t­ions for con­sci­en­tiousness, which is as­sociated with plan­ning; neu­rot­i­cism, a ten­den­cy to ex­pe­ri­ence neg­a­tive emo­tions that is as­sociated with sen­si­ti­vity to threat and pun­ish­ment; and agree­a­ble­ness, which re­lates to parts of the brain that al­low us to un­der­stand each oth­er’s emo­tions, in­ten­tions, and men­tal states. Only open­ness/in­tel­lect did­n’t as­sociate clearly with any of the pre­dicted brain struc­tures, the re­search­ers found.

“This starts to in­di­cate that we can ac­tu­ally find the bi­o­log­i­cal sys­tems that are re­spon­si­ble for these pat­terns of com­plex be­hav­ior and ex­pe­ri­ence that make peo­ple in­di­vid­u­als,” said De­Young. He points out, though, that this does­n’t mean your per­son­al­ity is fixed from birth; the brain grows and changes as it grows. Ex­pe­ri­ences change the brain as it de­vel­ops, and those changes in the brain can change per­son­al­ity.

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