Stress Hormones Promote Brain’s Building of Negative Memories

When a person experiences a devastating loss or tragic event, why does every detail seem burned into memory; whereas, a host of positive experiences simply fade away? According to a study recently published in  Neuroscience, it’s a bit more complicated than scientists originally thought. When people experience a traumatic event, the body releases two major stress hormones: norepinephrine and cortisol. In the brain, norepinephrine functions as a powerful neurotransmitter that can enhance memory, while research on cortisol has demonstrated that it can also have a powerful effect on strengthening memories. However, studies in humans up until now have been inconclusive – with cortisol sometimes enhancing memory while at other times having no effect. A key factor in whether cortisol has an effect on strengthening certain memories may rely on activation of norepinephrine during learning, a finding previously reported in studies with rats. This study demonstrated that human memory enhancement functions in a similar way. What researchers found was that “negative experiences are more readily remembered when an event is traumatic enough to release cortisol after the event, and only if norepinephrine is released during or shortly after the event.” To learn more about the study, click here.