Orgies alter the brain
New Scientist, 25 October 1997
sexual indulgence or abstinence can change the structure of the brain,
says a scientist in California. Marc Breedlove of Stanford University
put 10 male rats in with females given hormones to make them respond
readily to male advances. Nine other males were caged with females
treated to rebuff their attentions.
After a month, he examined a
part of the male rats' brains called the bulbocavernosus, which is
active during copulation. The motor neurons -- a category of nerve that
controls muscle fibres -- were significantly smaller in this area in
the males who had gorged on sex than in their celibate counterparts,
reports Breedlove in this week's Nature(vol 389, p 801). Hormone
injections made sure that all the male rats had the same levels of male
hormones, so the differences were presumably linked to the act of
Breedlove isn't exactly sure what his
findings mean. Smaller motor neurons fire more frequently, he notes, so
they may be primed for further action. "Or perhaps their smaller size
reflected ill heath after overuse."
But the take-home message,
says Breedlove, is that the structure of the brain and behaviour can
modify one another. "The brain not only controls our behaviour but is
altered by our experience," he says.