Center for BrainHealth Study Finds How Fear is Processed in the Mind

What happens in your mind when you see something scary?

Research from the Center for BrainHealth at The University of Texas at Dallas offers new answers after a team of scientists discovered how fear is processed by the brain.

“We are trying to find where thought exists in the mind,” said Dr. John Hart Jr., medical science director at the Center for BrainHealth, Distinguished Chair of Neuroscience and the Jane and Bud Smith Distinguished Chair in the School of Behaviorial and Brain Sciences.

“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.”

In a study recently published online in Brain and Cognition, Hart’s research team used electroencephalography (EEG) to identify theta and beta wave activity that signified the brain’s reaction to visually threatening images.

“We have known for a long time that the brain prioritizes threatening information over other cognitive processes,” said doctoral student Bambi DeLaRosa MS’12, lead author of the study. “These findings show us how this happens.”

For the study, 26 adult participants — 19 women and seven men ages 19 to 30 — wore EEG caps and were shown 224 random images that had real objects or were unidentifiably scrambled. Pictures with real objects were categorized as either threatening (weapons, combat, nature or animals) or nonthreatening (pleasant situations, food, nature or animals).

Participants were asked to push a button with their right index finger for images with real objects and another button with their right middle finger for the scrambled images. 

Response times were shorter for the scrambled images, but there was no difference in reaction time between the threatening and nonthreatening images.

The results showed that the threatening images evoked an early increase in theta wave activity in the occipital lobe, the area in the brain where visual information is processed. Theta wave activity also later increased in the frontal lobe, where higher mental functions such as thinking, decision-making and planning occur. 

“Theta wave activity starts in the back of the brain, in its fear center — the amygdala — and then interacts with the brain’s memory center — the hippocampus — before traveling to the frontal lobe,” DeLaRosa said. “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.”

The study will serve as a foundation for other studies that will examine fear associated with an object in other populations, including individuals with post-traumatic stress disorder.

The study was supported by the Berman Laboratory of Learning and Memory at The University of Texas at Dallas and the Jane and Bud Smith Distinguished Chair.