During a fearful experience, particular changes in brain activity patterns may predict whether a long-term fear memory is formed, according to researchers at the University of Amsterdam (UvA).
Until now, there was no way of predicting fear memory. Researchers also found it unclear whether the particular information stored in the long-term memory occurred at the time of fear or after the event.
The new study, conducted by Renee Visser M.Sc., Dr. Steven Scholte, Tinka Beemsterboer, M.Sc., and Prof. Merel Kindt, showed that future fear memories can be predicted by the patterns of brain activity that occur during the fearful experience.
While under magnetic resonance brain imaging (MRI), participants looked at neutral pictures of faces and houses, some of which were followed by a small electric shock — momentarily painful, but not enough to hurt the person or cause any long-term damage.
When images were paired with these small electric shocks, the researchers believed that this forced the subjects to form fear memories. The subjects showed fear responses when the pictures were paired with electric shocks.
This fear response can be measured in the brain, but is also made evident from increased pupil dilation.
After a few weeks, the participants came back to the lab and were shown the same images. Brain activity and pupil diameter were once again measured. The extent to which the pupil dilated when shown images previously followed by a shock was considered an outward sign of a fear memory.
In order to analyze the fMRI data, researchers compared the patterns of brain activity taken while participants viewed the images.
When pictures that had nothing in common (such as houses and faces) were tied to an electric response, there was an increase in neural pattern similarity. This pattern did not occur when the images were not linked to a fearful response.
The extent to which this occurred was an indication of fear memory formation: the stronger the response during learning, the stronger the fear response would be in the long term.
The results of the study may lead to greater insights into how emotional memories are formed. It may even be possible to conduct experimental research into how a fear memory is strengthened, weakened or even erased, without having to wait until the memory is expressed.
The study results are published in the scientific journal Nature Neuroscience.
Source: Nature Neuroscience