Genes and circuits for olfactory-associated long-term memory in Drosophila.

One of the formidable challenges in modern neuroscience is to identify the physical basis of long-term memory (LTM) storage−the engram. Cellular and molecular experiments have suggested that the engram for a particular behavioral task is encoded as changes in synaptic structure and function, yet distributed in an unknown fashion across an ill-defined neural circuit or network. Accumulating genetic and circuitry information has provided some clues toward resolving this engram puzzle.This review will focus on recent discoveries of genes and circuits involved in the formation of olfactory-associated LTM in Drosophila.