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Monday, September 12, 2011

Why you just can’t resist animals: Parts of the human brain hard-wired to respond to other creatures


Sensory overload: This picture of a rottweiler, a rabbit, a quail and a kitten has probably sparked an electrical storm in your brain

Humans respond strongly to animals - whether cute, threatening or just downright tasty - because our brains are hard-wired to, a new study has found.

Epilepsy patients whose brain activity was being monitored were shown a number of pictures of people, landmarks, animals or objects.

Researchers monitored the patients' amygdalae, two almond-shaped structures deep within the brain associated with emotion, fear and smell.

Our universal fascination with animals may have evolved as a need to react quickly to both predators and prey, say scientists at California Institute of Technology

'Our study shows that neurons in the human amygdala respond preferentially to pictures of animals, meaning that we saw the most amount of activity in cells when the patients looked at cats or snakes versus buildings or people,' said Florian Mormann, a research fellow at the California Institute of Technology.

'This preference extends to cute as well as ugly or dangerous animals and appears to be independent of the emotional contents of the pictures.

'Remarkably, we find this response behaviour only in the right and not in the left amygdala.'

Not only was activity in the right amygdala found to be greater, but neural responses were also faster for animal images. An identical response was later detcted in people without epilepsy.

Team leader Ralph Adolphs said past amygdala research had tended to focus on faces and fear, so it was a surprise to see that neurons in the right amygdala responded more to animals - of all species - than to human faces.

'I think this has the potential to help us better understand phobias of animals,' said Dr Adolphs.

Dr Mormann said the results indicate that the brain's right hemisphere evolved to deal with unexpected and biologically relevant stimuli.

'In terms of brain evolution, the amygdala is a very old structure, and throughout our biological history, animals - which could represent either predators or prey - were a highly relevant class of stimuli,' said Dr Mormann.

The research appears in the online journal Nature Neuroscience.



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