May 08, 2006
Localizing Dread via fMRI
Recent scans show that brain activity related to dread has been localized in the areas of the brain associated with pain. Dread was found in the parts of the pain network linked to attention. This is important because it suggests that dread is not as simple as fear or anixiety, which are emotions controlled by different brain regions.
A team of Emory University neuroscientists tried to understand the reasons why we tend to deal with dreadful decisions as quickly as possible. Using functional magnetic resonance imaging (fMRI), the team led by Gregory Berns, MD, PhD, has found the areas of the brain that are activated when someone experiences dread.
Trying to understand why people make rash decisions as a result of dread is a concept that the Emory team wanted to study. According the the scientists, "most people don't like waiting for an unpleasant outcome, and want to get it over with as soon as possible..the only explanation for this is that the dread of having something hanging over your head is worse than the thing that you are dreading." It is a commonplace experience, but the standard models of decision-making don't deal with this issue.
Each participant in the study was screened to determine their maximal pain threshold. While in the MRI scanner, participants underwent a series of 96 shocks. Before each shock, they were told how painful the shock would be (as a percent of their threshold) and how long they would have to wait for it. After the procedure, they were given the opportunity to choose between different intensity-delay combinations. The choice was always between more pain sooner or less pain later. The degree to which individuals chose more voltage sooner just to get a trial over was an indication of the dread they experienced from waiting. A total of 32 participants took part. Most of the participants preferred to speed up the waiting period and were deemed "mild dreaders", but 28% dreaded so much that they were willing to take more pain just to avoid waiting. These were labeled "extreme dreaders."
The findings showed that the mild and extreme dreaders had different patterns of brain activity. The extreme dreaders had more activity in the attentional parts of the pain matrix, and this activity was seen much earlier in each trial compared to the mild dreaders. The anatomical locations of dread responses suggest that the subjective experience of dread comes from the attention devoted to the expected physical response, and not simply a fear or anxiety response. The key factor seems to be that extreme dreaders devoted more attention toward the part of their body that was about to be shocked. This means that dread is not quite the same as fear or anxiety. These findings help to underscore the very real nature of dread. It also means that dread can be mitigated by diverting attention.
According to Dr Berns, "the dread associated with things like medical procedures or public speaking can probably be alleviated by diverting one's attention during the waiting period. The benefits could be substantial if it means that we act more rationally in terms of getting healthcare, or decreasing the psychological toll of dread and anxiety."
Posted by rsk at May 8, 2006 11:49 PM