The science of hate: The study reports that the 'hate circuit' includes structures in the cortex and in the sub-cortex and has components that are important in generating aggressive behaviour.
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SYDNEY: By showing people images of hated ex-lovers or colleagues, and simultaneously scanning their brains, researchers have identified areas of activity that add up to what they describe as a 'hate circuit'.
"Hate is often considered to be an evil passion that should, in a better world, be tamed, controlled, and eradicated. Yet to the biologist, hate is a passion that is of equal interest to love," said Semir Zeki lead author of a study detailing the research.
Link to aggression
Zeki and co-worker John Romaya – both neurobiologists at University College London, in England – have shown that this 'hate circuit' is distinct from brain activity related to emotions such as fear, threat and danger, but it shares a part of the brain associated with aggression.
The results, published today in the journal PLoS One, are an extension of previous work on the brain mechanisms of romantic and maternal love from the same laboratory.
The hate circuit is quite distinct from that associated with romantic love, the authors said, though it shares at least two common structures with it.
"Like love, [hate] is often seemingly irrational and can lead individuals to heroic and evil deeds," said Zeki. "How can two opposite sentiments lead to the same behaviour?"
To compare their current finding with previous studies of romantic love, Zeki and Romaya studied hate directed against a specific individual.
Something like love
Seventeen subjects, both female and male, had their brains scanned while viewing pictures of the hated person of their choice, as well as that of neutral faces with which they were familiar.
The study reports that the 'hate circuit' includes structures in both the cortex and sub-cortex of the brain and has components that are important in generating aggressive behaviour. It also involves a part of the frontal cortex that has been considered critical in predicting the actions of others, probably an important feature when one is confronted by a hated person.
The subcortical activity involves two distinct structures, the putamen and the insula, the researchers said.
The former, which has been implicated in the perception of contempt and disgust, may also be part of the motor system that is mobilised to take action, since it is known to contain nerve cells that are active in phases preparatory to making a move.
Both structures have also been found to be activated by romantic love, said Zeki.
"The putamen could… be involved in the preparation of aggressive acts in a romantic context, as in situations when a rival presents a danger," he explained. "The insula may be involved in responses to distressing stimuli, and the viewing of both a loved and a hated face may constitute such a distressing signal."
Varieties of hate
One marked difference in patterns of brain activity, is that in romantic love, parts of the cerebral cortex associated with judgment and reasoning become deactivated, said Zeki, but this didn't happen when the 'hate circuits' of the test subjects were activated.
He said that this is likely because lovers tend to be less critical and judgmental of one another, but in the context of hate it may be beneficial to exercise judgment in calculating moves to harm a rival.
Another difference to the expression of romantic love is that hate can be directed at entire groups of people, as is the case with racial, political, or gender hatred, said the researchers. Uncovering how these varieties of hate manifest themselves in the brain is a topic of future study for the researchers.
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With University College London.
