30 April 2010

Oxytocin impacts learning processes

by Kate Melville

Released on a massive scale during orgasm, the neuropeptide oxytocin is also known to trigger childbirth and strengthen the emotional bond between a mother and new-born child. Now, researchers have found that it can also have a dramatic effect on men's emotional empathy and learning processes.

In the latest experiments, half the male participants received an oxytocin nose spray and the other half a placebo. The researchers then showed the test subjects photos of emotionally charged situations in the form of a crying child, a girl hugging her cat and a grieving man. The test subjects were then asked to express the depth of feeling they experienced.

The researchers observed "significantly higher emotional empathy levels" for the oxytocin group than for the placebo group, despite the fact that the participants in the placebo group were able to provide rational interpretations of the facial expressions displayed. Researcher René Hurlemann, of Bonn University, said the administration of oxytocin had the effect of enhancing the ability to experience fellow-feeling. "The males under test achieved levels which would normally only be expected in women," noted Hurlemann.

In a second experiment, the participants had to use computers to complete a simple observation test. Correct answers produced an approving face on the screen, wrong ones a disapproving one. Alternatively, the feedback appeared as green (correct) or red (false) circles.

"In general, learning was better when the feedback was shown in the form of faces," said co-researcher Keith Kendrick. "But, once again, the oxytocin group responded clearly better to the feedback in the form of facial expression than did the placebo group."

Kendrick hypothesized that the brain's so-called amygdaloid nucleus may play an important role. This cerebral structure, known generally as the amygdala, is involved in the emotional evaluation of situations. Certain people suffer from an extremely rare hereditary disease which progressively affects the amygdala. "We were lucky to be able to include two female patients in our study group who were suffering this defect of the amygdala," explained Hurlemann. "Both women reacted markedly worse to approving or disapproving faces in the observation test than did other women in a control group. Moreover, their emotional empathy was also affected." Hence, the researchers suspect that the amygdala could bear some form of co-responsibility for the effect of the oxytocin.

The research team now speculates that the hormone could be useful as a medication for conditions such as schizophrenia, which are frequently associated with reduced social approachability and social withdrawal.

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Source: University of Bonn