According to an old saying, the opposite of love isn’t hate but indifference. Recent scientific studies show that there is some truth to this claim. The areas of the brain associated with hate are entirely different from those associated with other negative emotions, including fear and sadness. Fear and sadness are significantly correlated with neuronal activation in the subcortical almond-shaped structure known as the “emotional brain” or the “amygdala”.
Researchers from University College London looked at the brains of 17 subjects while they were viewing pictures of people they hated. They found that while hate activated both cortical and subcortical parts of the brain, it didn’t activate the amygdala.
In the cortex, hate gave rise to activity in areas involved in the guidance and planning of action. These include parts of the parietal cortex on the top of brain and prefrontal areas at the forefront of the brain. Hate is thus closely correlated with deliberate action.
In the subcortical brain, hate activated the putamen and the insula. These areas have been associated with disgust, contempt and aggression.
The putamen and the insula also show increased activity in cases of romantic love, particularly when obsession is involved. This may come as a surprise at first. However, when you think about the nature of obsessive love, it makes sense that it would activate areas of the brain associated with negative emotions. In obsessive love, disgust, contempt and aggression can come from the thought of the other person being involved with other people or not returning the positive emotions.
The main difference between love and hate lies in their effects on the rational brain. In cases of obsessive love, large areas of the frontal cortex are inhibited, which explains the irrational actions people make when they are obsessed with another person.
In cases of hate, only tiny areas of the frontal cortex are inhibited. This indicates that there is more rationality in (pure) hate than in love. Irrational hate probably is a more complicated emotion that could involve love as well as hate.
The researchers also found something of possible legal consequence. The reported intensity of hate correlated perfectly with the brain activity identified in the brain images. This could have legal consequences, because brain imaging could be used as a kind of lie detector to test whether true hate is present.
Source: Zeki et al. Neural Correlates of Hate. PLoS ONE, 2008.
Dr. Berit Brogaard ("Dr. Brit") has written since 1999 for publications such as "Journal of Philosophy,", "Journal of Biological Chemistry," "Consciousness and Cognition," "Cognitive Science," and "Journal of Medicine and Philosophy". In her academic research, she specializes in rare brain conditions such as synesthesia and blindsight, brain intervention and emotional regulation. From 2007 to 2009 she was a research fellow at the Centre for Consciousness at the Australian National University. She has D.M.Sci. in neuroscience from the Danish National Hospital and the University of Copenhagen and a Ph.D. in philosophy from State University of New York at Buffalo.