Spray said to turn people to pushovers

May 21, 2008
Courtesy Cell Press
and World Science <http://www.world-science.net/> staff

Re­search­ers have iden­ti­fied brain cen­ters
acti­vated by be­tray­al of trust—and a way to keep them
quiet.

A spray of a hor­mone, ox­y­to­cin, makes peo­ple
keep trust­ing even some­one who has be­trayed them, the
scientists ex­plained. They presented the findings not as a trick
for, say, cheat­ing spouses to keep their part­ners
coop­erative, but as an in­sight into the mind with possible
cli­ni­cal value.

Thom­as Baum­gart­ner of the Uni­ver­s­ity of
Zu­rich and col­leagues said their work could help re­veal
the brain wir­ing be­hind trust and pos­sibly the ba­sis
of so­cial dis­or­ders such as pho­bias and au­tism.
The find­ings are re­ported in the May 22 is­sue of the
re­search jour­nal Neu­ron.




Amygdala activation, shown in red in a cross-sec­tion of the brain
in an fMRI image. (Cou­rtesy NIMH Cli­n­i­cal Brain
Dis­ord­ers Branch)


The in­ves­ti­ga­tors asked vol­un­teers to play
a "trust game" in which they con­tri­but­ed
mon­ey to a hu­man trus­tee, who would ei­ther
in­vest it and re­turn the prof­it­s—or be­tray
them and keep it all.

Some play­ers al­so re­ceived a na­sal spray
con­tain­ing the brain chem­i­cal and hor­mon
ox­y­to­cin, found in pre­vi­ous stud­ies to
make peo­ple more trust­ing.

The re­search­ers found that stiffed play­ers who had
re­ceived ox­y­to­cin went on trust­ing their
treach­er­ous part­ners. Play­ers who had re­ceived
an in­ac­tive spray in­stead of ox­y­to­cin did
not.

Ox­y­to­cin was al­so found to re­duce
ac­ti­vity in two brain re­gions: the amyg­da­la,
which pro­cesses fear, dan­ger and pos­sibly risk of
so­cial be­tray­al; and an ar­ea of the stria­tum,
part of the cir­cuit­ry that guides and ad­justs fu­ture
be­hav­ior based on re­ward feed­back.

These ox­y­to­cin-as­so­ci­at­ed changes,
re­search­ers said, oc­curred only when play­ers
be­lieved an ac­tu­al per­son was mak­ing the
de­ci­sions about their mon­ey. The changes did­n't
oc­cur in a sep­a­rate "risk game," where
sub­jects were told a com­put­er would ran­domly
de­cide wheth­er their mon­ey would be re­paid or not.

Play­ers' brains were scanned us­ing func­tion­al
mag­net­ic res­o­nance im­ag­ing, or fMRI, a
tech­nique in which harm­less mag­net­ic fields and
ra­dio waves are used to mon­i­tor brain ac­ti­vity
by map­ping blood flow in the organ.

"Our in­sights in­to the neu­ral cir­cuit­ry of
trust adapta­t­ion, and ox­y­to­cin's role in
trust adapta­t­ion, may al­so con­trib­ute to a
deeper un­der­stand­ing of men­tal dis­or­ders
such as so­cial pho­bia or au­tism that are
as­so­ci­at­ed with so­cial deficits," the
re­search­ers wrote. "In par­tic­u­lar,
so­cial pho­bia (which is the third most com­mon men­tal
health dis­or­der) is char­ac­ter­ized by
per­sist­ent fear and avoid­ance of so­cial
in­ter­ac­tions."

The work "has sig­nif­i­cant im­plica­t­ions
for un­der­stand­ing men­tal dis­or­ders where
deficits in so­cial be­hav­ior are ob­served," wrote
psy­cholo­g­ist Mauri­cio Del­ga­do of
Rut­gers Uni­ver­s­ity in New Jer­sey, who was not
in­volved in the re­search, in a pre­view in the same
is­sue of the jour­nal. Fear of be­trayal, for
ex­am­ple, "could serve as a pre­cur­sor to
so­cial pho­bia," he con­tin­ued, adding that the
ox­y­to­cin find­ing sug­gests
"po­ten­tial clin­i­cal
ap­plica­t­ions."


http://www.world-science.net/othernews/080521_oxytocin
<http://www.world-science.net/othernews/080521_oxytocin>



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