A memory of neurobiology

Author:  Metcalfe David
Date:  October 2007

Most people have experienced vivid recall of memories that relate to significant life events. Now, a paper published in Cell earlier this month has shown that the hormone noradrenaline, released during periods of high emotion, strengthens connections between neurons in the brain. As a result, the brain distinguishes between significant and insignificant events when allocating its memory capacity.

According to senior author Roberto Malinow at the Cold Spring Harbor Laboratory in New York, this phenomenon is something everyone can identify with. "You can probably remember where you were when you heard about 9/11, but you probably don't know where you were on 9/10." Noradrenaline now appears to mediate at least one mechanism underlying this effect and may result in novel therapies for pathologies such as post-traumatic stress disorder in which patients suffer persistent memories of traumatic life experiences.

Using mice, Malinow and his colleagues found that noradrenaline release during emotional arousal modified GluR1 receptors at the receiving ends of neurons. This increased the strength of neuronal interconnections and, in doing so, potentiated memory. In addition, exposing mice to noradrenaline increased their ability to recall past events, while generating mutations in their GluR1 receptors substantially retarded their memory. Furthermore, blocking GluR1 receptors in humans can hinder the influence of emotion on memory. As a result of their data, the authors have concluded that noradrenaline and GluR1 provide "a molecular mechanism for how emotion enhances learning and memory."

Written by David Metcalfe

Reviewed by Frances Mao

Published by Pooja Ghatalia