Forgetting Is Regulated through Rac Activity in Drosophila

SummaryInitially acquired memory dissipates rapidly if not consolidated. Such memory decay is thought to result either from the inherently labile nature of newly acquired memories or from interference by subsequently attained information. Here we report that a small G protein Rac-dependent forgetting mechanism contributes to both passive memory decay and interference-induced forgetting in Drosophila. Inhibition of Rac activity leads to slower decay of early memory, extending it from a few hours to more than one day, and to blockade of interference-induced forgetting. Conversely, elevated Rac activity in mushroom body neurons accelerates memory decay. This forgetting mechanism does not affect memory acquisition and is independent of Rutabaga adenylyl cyclase-mediated memory formation mechanisms. Endogenous Rac activation is evoked on different time scales during gradual memory loss in passive decay and during acute memory removal in reversal learning. We suggest that Rac's role in actin cytoskeleton remodeling may contribute to memory erasure.PaperClip To listen to this audio, enable JavaScript on your browser. However, you can download and play the audio by clicking on the icon belowHelp with MP3 filesOptionsDownload audio (2622 K)

Graphical AbstractFigure optionsDownload high-quality image (285 K)Download as PowerPoint slideHighlights
► Memory decay is bidirectionally regulated by genetic manipulation of Rac activity
► Interference-induced forgetting is suppressed by Rac inhibition
► Flexible behavior in reversal learning is altered by Rac activity manipulation
► Endogenous Rac is activated in parallel with forgetting