Light-dependent memory maintenance regulated by circadian clock neurons

Takaomi Sakai

Department of Biological Sciences, Tokyo Metropolitan University

In animals, a newly acquired memory is consolidated in the brain and converted into a stable long-term memory （LTM）.　It is considered that transcriptional activation and novel protein synthesis are essential for LTM consolidation and maintenance in various animal species.　Since animals receive a variety of external stimuli during learning, it is not hard to imagine that LTM is consolidated by learning-dependent novel protein synthesis in the brain.　However, they should lead a normal life after animals acquire LTM.　Nevertheless, why is it possible to continue to supply the proteins necessary for LTM maintenance to the neurons that have acquired LTM?　Recently, we found that Drosophila uses environmental light to maintain LTM and that circadian clock neurons regulate this light-dependent LTM maintenance.　In this review, we outline the “light-dependent LTM maintenance system” found in Drosophila and discuss the regulatory mechanisms of LTM by circadian clock neurons.

Address correspondence to Dr. Takaomi Sakai, Department of Biological Sciences, Tokyo Metropolitan University （1-1, Minamiosawa, Hachioji, Tokyo 192-0397, Japan）