Systems memory consolidation in Drosophila

From an information processing perspective, memories need to be acquired, encoded, stored, maintained and retrieved. As time passes after training, memories become less easily retrieved, but also become progressively more stable in the face of experimental perturbations. This process is referred to as consolidation. But the term has been used to describe two different biological processes whose relationship is poorly understood [1,2]. The first, which we refer to as biochemical consolidation, involves cell-signaling events within a neuron. The second, which we call systems consolidation, involves ongoing communication between brain regions or cell types. Although systems consolidation was first thought to be at play only in complex brains, a number of recent studies reveal its importance in Drosophila. The ease of cell type specific genetic manipulations in flies provides a unique opportunity to forge an integrated mechanistic understanding of biochemical and systems consolidation.

► Olfactory memory in Drosophila involves both biochemical and systems consolidation. ► Persistent activity in an intra-mushroom body feedback loop underlies labile memory. ► Consolidated memory involves a second feedback loop onto mushroom bodies.