[ 2007-04-20 10:46 ]
It may be better to have loved and lost than never
to have loved at all, but why is it so hard to find again? It may be that our
brains are fixated on our former lovers, according to scientists.
Researchers at Florida State University examined the nature of love by
studying the brains and behavior of male prairie voles, picked for their habit
of lifelong monogamy and aggression
towards other females once they have found a mate.
The scientists found that males became devoted to females only after they had
mated. The bond coincided with a huge release of the feel-good chemical
dopamine inside their brains.
Brandon Aragona, who led the study, demonstrated that dopamine was the voles'
love drug by injecting the chemical into the brains of males who had not yet had
sex with female companions. Immediately, they lost interest in other females and
spent all of their time with their chosen one. Further experiments showed that
dopamine restructured a part of the vole's brain called the nucleus accumbens, a
region that many animals have, including humans. The change was so drastic that
when paired-up males were introduced to new females, although their brains still
produced dopamine on sight, the chemical was channeled into a different neural
circuit that made them go cold towards the new female.
"It seems that the first time they get together and the bond forms, it locks
them into that monogamous behavior ... You can take a female away from a male
once he's formed a bond with her and two weeks later put him with a different
female and he won't be remotely interested," said Dr Aragona, whose study
appears in the journal Nature Neuroscience.
The researchers said that while the love lives of voles differ from those of
humans, the same brain structures work in much the same ways across different
species. "Things are always going to be more complicated in humans because we
have larger brains and are under different pressures, but the basic mechanisms
are there", said Dr Aragona.
（来源：英文阅读网 实习生江巍 英语点津 Annabel编辑）