For Don Timoh - Final Project

3/1 4/2 010 P sych opath s K eep T heir E yes o n t h e P riz e scie n cem ag .o rg .e zp ro xy.n eu .e d u /n ew s/2 010/0 3/p sych opath s-k e ep-th eir -e ye s-p riz e I m puls iv e b ra in .

Activ it y in th e n ucle us a ccu m bens s p ik e s h ig her fo r m ore im puls iv e p eople w hen th ey w ait fo r a r e w ard B uckh olt z e t a l. , N atu re N euro scie nce ( 2 010) B y Mic h ael T o rric e Mar. 1 4, 2 010 , 2 :0 0 P M W heth er it in vo lv e s g am blin g a w ay o ne's lif e s a vin gs o r c o m mit tin g o ne m urd er a fte r a noth er, a p sych opath i n evit a bly le ave s th e r e st o f u s w onderin g:

What w as g oin g o n in h is h ead? N ow r e se arc h ers r e port th at p art o f th e a nsw er m ay b e h yp ers e nsit iv it y to r e w ard s, w hic h m ay c re ate a p ath olo gic a l d riv e fo r m oney, s e x, a nd s ta tu s.

A ll p sych opath s s h are tw o c h ara cte ris tic tr a it s : a n in abilit y to e m path iz e w it h o th ers ' e m otio ns, s u ch a s th e fe ar in a p ers o n's fa ce , a nd im puls iv e , anti- s o cia l b ehavio r, s u ch a s r e ckle ss r is k ta kin g o r e xce ssiv e a ggre ssio n.

N euro scie ntis ts h ave p in poin te d n eura l m ech anis m s th at m ay c a use psych opath s' la ck o f e m path y. B ut v e ry lit tle r e se arc h h as lo oke d a t w hat le ads to im puls iv it y -w hic h in s o m e w ays m ig ht b e m ore im porta nt, b eca use it ca n h elp p re dic t a p sych opath 's te ndency to w ard s v io le nt c rim e.

N euro scie ntis t J o sh ua B uckh olt z o f V anderb ilt U niv e rs it y in N ash ville a nd h is c o lle agues d ecid ed to fo cu s o n a s yste m o f in te rc o nnecte d b ra in r e gio ns ca lle d th e m eso lim bic s yste m , w hic h m otiv a te u s to h unt fo r r e w ard s b y r e le asin g th e n euro tr a nsm it te r d opam in e. D ru gs lik e h ero in e-to w hic h p sych opath s are a ls o m ore s u sce ptib le — ca n p ush c ir c u it s in th is s yste m in to o ve rd riv e , le avin g a ddic ts c o m puls iv e ly s e ekin g a noth er h it . T he r e se arc h ers h yp oth esiz e d th at p sych opath s m ig ht a ls o o ve rre act to o th er r e w ard s.

T o te st th eir h yp oth esis , th e s cie ntis ts s tu die d h ow n orm al p ers o nalit y is a ffe cte d b y v a ria tio ns in th e n ucle us a ccu m bens, a p art o f th e m eso lim bic syste m in vo lv e d in m otiv a tio n. T hey g ave 3 0 v o lu nte ers a s m all d ose o f a m pheta m in e, a s tim ula nt, a nd u se d a P ET s ca nner to m easu re h ow m uch d opam in e th eir n ucle us a ccu m bens r e le ase d. T hey c o m pare d th at m easu re m ent w it h te sts th e v o lu nte ers h ad ta ke n th at m easu re im puls iv it y a nd e m path y. P eople sco rin g a bove a h ig h-im puls iv it y c u to ff r e le ase d fo ur tim es m ore d opam in e th an th ose b elo w th e c u to ff. F or th e s e co nd e xp erim ent, s u bje cts la y in a fM RI m ach in e. T hey c o uld s co re u p to $ 5 if th ey p re sse d a b utto n w hile a w hit e s q uare fla sh ed o n a c o m pute r s cre en. T he fM RI d ete cte d g re ate r le ve ls o f a ctiv it y in th e n ucle us a ccu m bens o f im puls iv e h ig h s co re rs a s th ey a ntic ip ate d th e s q uare .

T hese c o rre la tio ns, th e r e se arc h ers r e port o nlin e to day in Natu re N euro scie nce , s u ggest th at th e g re ate r th e a ctiv it y i n a p ers o n's d opam in e cir c u it s w hen th ey a ntic ip ate r e w ard s, th e m ore im puls iv e th eir p ers o nalit y . F or p sych opath s, e ve ry d ay r e w ard s m ay tr ig ger a bnorm ally la rg e m eso lim bic syste m r e sp onse s, a nd th us c re ate a n o ve rw helm in g d riv e to s e ek o ut s o m eth in g r e w ard in g d esp it e th e c o nse quence s o f th eir a ctio ns, B uch holt z s a ys. H e belie ve s th at t h is m otiv a tio n c o uple d w it h a la ck o f e m path y le ads to c rim e.

W hile in tr ig uin g, th is m odel " n eeds m ore d ata to m ake it fly ," s a ys b ehavio ra l n euro scie ntis t K la us M ic ze k o f T u fts U niv e rs it y in M edfo rd , Massa ch use tts . T he r e se arc h ers e sp ecia lly n eed to a cco unt fo r d opam in e's o th er r o le s, s u ch a s r e sp ondin g to s tr e ss, b eca use it s r e le ase h ere m ay n ot b e so le ly d ue to r e w ard . B uckh olt z c o unte rs th at th e d opam in e r e le ase d ata c o rre la te s w it h th e b ra in a ctiv it y d ata , s u ggestin g th at d opam in e s p ik e d a s th e vo lu nte ers a ntic ip ate d th e $ 5 r e w ard .

B eca use o f th e m eso lim bic s yste m 's c o nnectio n w it h a ddic tio n, n euro scie ntis t K ent K ie hl o f th e U niv e rs it y o f N ew 1/2 M exic o , A lb uquerq ue, belie ve s th at th e fin din gs c o uld u lt im ate ly h ave " h uge im plic a tio ns" fo r s u bsta nce a buse t r e atm ents th at s e ek to d am pen a ctiv it y in d opam in e c ir c u it s . A lc o hol a nd d ru gs c a n fu rth er d is ru pt a p sych opath 's a bilit y to p ut th e b ra ke s o n aggre ssiv e , r is ky b ehavio r. " S o fin din g s o m e w ay to tr a nsla te th is d ata in to ta rg ete d t r e atm ents c o uld b e h ugely b enefic ia l, " K ie hl s a ys.

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