http://www.sciencedaily.com/releases/2009/01/
     090106170744.htm  
Hormone Improves Human Ability To Recognize Faces But Not Places
ScienceDaily (Jan. 9, 2009) — Oxytocin, a hormone involved in child-birth and breast-feeding, helps
people recognize familiar faces, according to new research in the
January 7 issue of The Journal of Neuroscience. Study participants who
had one dose of an oxytocin nasal spray showed improved recognition
memory for faces, but not for inanimate objects.
"This is the first paper showing that a single dose of oxytocin
specifically improves recognition memory for social, but not for
nonsocial, stimuli," said Ernst Fehr, PhD, an economist at the
University of Zurich who has studied oxytocin's effect on trust and is
unaffiliated with the new study. "The results suggest an immediate,
selective effect of the hormone: strengthening neuronal systems of
social memory," Fehr said.
In mice, oxytocin has been shown to be important in social
recognition — remembering that another mouse is familiar. Unlike
humans, who use visual cues, mice use smell to recognize and
distinguish other mice.
In humans, oxytocin increases social behaviors like trust, but its
role in social memory has been unclear. "Recognizing a familiar face is
a crucial feature of successful social interaction in humans," said
Peter Klaver, PhD, at the University of Zurich, the senior author of
the new study, which was led by Ulrike Rimmele, PhD, at New York
University. "In this study, we investigated for the first time the
systematic effect of oxytocin on social memory in humans," Klaver said.
Klaver and colleagues had study participants use a nasal spray
containing either oxytocin or a placebo and then showed them images of
faces and inanimate objects, including houses, sculptures, and
landscapes. Participants were given a surprise test when they returned
the next day — they were shown some of the images they had seen the day
before as well as some new ones and were asked to distinguish between
images that were "new," images that they specifically "remembered"
being presented, and images they recognized ("knew") as familiar but
could not recall the presentation context.
Volunteers who used the oxytocin spray more accurately recognized
the faces they had seen before than did those in the placebo group.
However, the two groups did not differ in recognizing the other,
nonsocial images, suggesting that oxytocin specifically improved social
memory and that different mechanisms exist for social and nonsocial
memory. Further analysis showed that oxytocin selectively improved the
discrimination of new and familiar faces — participants with oxytocin
were less likely to mistakenly characterize unfamiliar faces as
familiar. "Together, our data indicate that oxytocin in humans
immediately strengthens the capability to correctly recognize and
discriminate faces," Klaver said.
"The study highlights the parallels in social information processing
in mice and man, and adds further support to the notion that oxytocin
plays a critical role," said Larry Young, PhD, at Emory University, an
expert on oxytocin who is unaffiliated with the current study. "This
has important implications for disorders such as autism, where social
information processing is clearly impaired," Young said.
The research was supported by the Swiss National Science Foundation,
the Swiss Federal Institute of Sports, and the University of Zurich.

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