Fear is an emotion unlike any other. It has the ability to affect every facet of our mind and bodies: from dampering our ability to rationally process external stimuli, to even preventing us from moving our bodies. Regardless of these things, fear remains vital to us in dealing with seen and unseen dangers, but what is it exactly? How does it work? Well, like all emotions, fear and anxiety boil down to brain chemistry. Both have been thoroughly researched over the years, but a new study has laid the foundation for a better understanding of how they go into overdrive. This, in turn, has shed light on conditions like post-traumatic stress disorder (PTSD) and can help us develop better treatments.
Scientists from the University of Texas used electroencephalography (EEG) — a method of recording electrical activity across the scalp — to measure how the brain is affected by prolonged exposed to threatening images. This is the first reputable study to identify any electrophysiological marker for danger in the brain; it was done by seeing and measuring exactly how the images provoked an emotional reaction.
Interestingly, while the study was small, with only 24 adults taking part, the groundwork was built using decades of cognitive research dealing with both animal and human subjects.. paying special attention to how the brain prioritizes threatening information. So, in essence, this research explains many things, like why we lose our train of thought if we are suddenly spooked by something.[su_pullquote]
“There is nothing to fear but fear itself.”
– Franklin D. Roosevelt
[/su_pullquote]The mind is like an orchestra, with different instruments of the brain working in cohorts with one singular purpose: keeping you in good working order. Bundles of electrically active neurons create patterned frequencies, telling other areas of the brain what to do. Figuring out which patterns occur when the brain is stimulated in a particular fashion allows us to correlate the electrical signals with what we know as fear.
Moving back to the study, 19 females and 7 males between the ages of 19 and 30 were shown a mix of 224 randomizes images that were either distorted beyond recognition, or clear pictures of something easily discernible. The real images fit into one of two categories: they were either threatening pictures (combat, weapons, nature and animals) or non-threatening (pleasant situations, food, nature and animals). While wearing an EEG cap, the subjects were asked to press a button with their right index finger for real images and a different button for the scrambled images.
The EEG caps monitored changes in theta and beta brain wave activity when exposed to the fear-inducing images. They didn’t discover any significant difference in reaction time between the threatening images and the non-threatening ones. However, they did learn:
“Threatening images evoked an early increase in theta activity in the occipital lobe, followed by a later increase in theta power in the frontal lobe. A left lateralized desynchronization of the beta band, the wave pattern associated with motor behavior, also consistently appeared in the threatening condition.”
The fluctuations in theta activity engage higher mental activity in the frontal lobe, for things like decision making and planning, after the visual imagery is first received by the occipital lobe. The change in beta waves accounts for the impulse to run when under threat.
“We have known for a long time that the brain prioritizes threatening information over other cognitive processes,” explained 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 its fear center — the amygdala — and then interacts with brain’s memory center — the hippocampus — before traveling to the frontal lobe where thought processing areas are engaged. At the same time, beta wave activity indicates that the motor cortex is revving up in case the feet need to move to avoid the perceived threat.”
As previously stated, this study is very small an does not amount to much in the overall field of neuroscience. However, it does provide the opportunity for more work to be carried out with sufferers of PTSD and similar conditions (conditions where fear and anxiety become overbearing). The researchers hope their findings can aid work carried other neurologists about what triggers flashbacks to traumatic events and how the brain registers conditional fear.
The study was published online in Brain and Cognition in September.