The dynamic engram: fear memories and the basolateral amygdala

Publication date: Available online 18 December 2017
Source:Brain Research Bulletin
Author(s): Patrick Davis, Leon G. Reijmers
Great progress is being made in our understanding of how the brain stores and retrieves memories, which is exemplified by continuous discoveries of novel spatial and temporal components of so-called memory engrams. These discoveries have led to the realization that engrams are controlled by complex spatiotemporal dynamics across scales that span from molecules to brain regions, and from milliseconds to years. Moreover, it is now clear that across the lifetime of an engram, many of its spatial and temporal properties are not fixed, but instead change in complex ways. The dynamic nature of engrams is especially relevant in the case of fear memories, whose contributions to an animal's fitness depend on a delicate balance of stability and flexibility. Though most fear memories last a lifetime for an obvious reason, their expression also needs to be highly regulated to prevent the maladaptive behavior caused by anxiety disorders. To achieve the right balance of stability and flexibility, fear engrams are subjected to complex spatiotemporal dynamics, making them informative examples of the "dynamic engram". This review will focus on the contributions of the basolateral amygdala (BLA) to the dynamic properties of fear engrams.



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