A Neural Mechanism of Biological Active Forgetting

However, the understanding to the neural mechanism of active forgetting is still limited. Our latest biological data in drosophila indicated that Rac1-dependent active forgetting is achieved by regulating a synaptic expansion-convergence process. Specifically, learning of a new experience triggers the increase and subsequent elimination in the number of presynaptic active zones (AZs, i.e., the site of neurotransmitter release), which is regulated by Rac1 signaling pathway (Figure 1). After learning an aversive olfactory conditioning task, the number of AZs is significantly increased followed by elimination within the mushroom body lobe where a new memory is formed (Figure 1, a, b). The time course of AZ addition-induced elimination is in parallel with Rac1-dependent active forgetting that lasts for only hours (Figure 1, a, b). In particular, inhibition of Rac1 and its downstream Dia specifically blocks the increase of the number rather than the size of AZs.