Revealed — how fear originates in the brain

A study is published in the journal Brain and Cognition has revealed how the feeling of fear originates in the brain when people are exposed to threatening images.

By: Agencies | | Published: September 17, 2014 3:08 pm

A study is published in the journal Brain and Cognition has revealed how the feeling of fear originates in the brain when people are exposed to threatening images.

Researchers from the Center for BrainHealth at The University of Texas at Dallas mapped brain activity in 26 adults (19 female, 7 male), aged 19-30 years. They were shown 224 randomised images that were either unidentifiably scrambled or real pictures. Real pictures were separated into two categories: threatening (weapons, combat, nature or animals) and non-threatening (pleasant situations, food, nature or animals).

The participants were made to wear an EEG cap and were asked to push a button with their right index finger for real items and another button with their right middle finger for nonreal/scrambled items. It was found that pariticipants had a shorter response time for scrambled images than real images. However, there was no difference in reaction time for threatening versus non-threatening images.

EEG results showed that threatening images evoked an early increase in theta activity in the occipital lobe (the area in the brain where visual information is processed), followed by a later increase in theta power in the frontal lobe (where higher mental functions such as thinking, decision-making, and planning occur). A left lateralised desynchronisation of the beta band, the wave pattern associated with motor behaviour (like the impulse to run), also consistently appeared in the threatening condition.

‘We know that groups of neurons firing on and off create a frequency and pattern that tell other areas of the brain what to do. By identifying these rhythms, we can correlate them with a cognitive unit such as fear,’ said John Hart, Medical Science Director at the Center for BrainHealth. Utilising electroencephalography (EEG), Hart’s research team identified theta and beta wave activity that signifies the brain’s reaction to visually threatening images.

‘We have known for a long time that the brain prioritises threatening information over other cognitive processes,’ said Bambi DeLaRosa, lead author of the study. ‘These findings show us how this happens. Theta wave activity starts in the back of the brain, in it’s fear center — the amygdala — and then interacts with brain’s memory center — the hippocampus — before travelling to the frontal lobe where thought processing areas are engaged.

With inputs from PTI

Photo source: Getty images

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Published: September 17, 2014 3:08 pm

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