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Senses and Memories Can be Strengthened by Anxiety
> 4/1/2008 1:32:05 PM

Touch a scalding pan without mittens once and you will hesitate before being so impatient again. While you might rather remember the idyllic days of your vacation to Hawaii, our brains try to keep us safe by more strongly imprinting the memories surrounding traumatic experiences. A study published in the March issue of Science managed to directly observe this boosted memory storage, and it went further to show that information processing can be significantly altered at the very first step, the perception of a stimulus.

Dr. Wen Li led a team of researchers from Northwestern University in an experiment that tested the ability of subjects to pick out a subtle difference in scents. These scents were enantiomers, meaning that they were incredibly similar but had molecular structures that were mirror-images of each other. Humans cannot normally detect this difference, a limitation that was confirmed for each of the ten subjects in the experiment.

For the next step of the experiment, Dr. Li shocked her brave volunteers each time that they were exposed to the target enantiomer. This tough learning experience enabled subjects to identify the enantiomer two out of three times rather than one out of three (chance). Their sense of smell had been boosted to sense things previously undetectable. MRIs taken during the shock phase of the experiment revealed clear differences in the way that trauma-associated memories were encoded in the olfactory region of the brain.

Enhanced senses may help people avoid danger in the future, but they can also cripple the mind with their intensity. Dr. Li's research reveals a way that a normally adaptive defense can create problems like post-traumatic stress disorder. For example, it may be that a soldier's memory of napalm is more intense than normal memories, and his ability to smell gasoline is heightened, increasing the chances of panicked flashbacks. Therapists may be able to use this knowledge to defuse anxiety-provoking associations before they cement. It is also possible that pharmaceutical companies may find a way to chemically induce the mind to stand down from high-alert.

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