Active Protection: Learning-Activated Raf/MAPK Activity Protects Labile Memory from Rac1-Independent Forgetting

Area of Science:

• Neuroscience
• Molecular Biology
• Animal Behavior

Background:

• Labile memory is inherently unstable and prone to forgetting.
• Mechanisms maintaining memory stability against disruption are not fully understood.
• Active forgetting is known, but active protection mechanisms require elucidation.

Purpose of the Study:

• To investigate the mechanisms of labile memory protection against disruption in Drosophila.
• To identify molecular pathways involved in learning-activated memory stabilization.
• To understand the interplay between active protection and active forgetting.

Main Methods:

• Aversive olfactory conditioning in Drosophila.
• Analysis of mitogen-activated protein kinase (MAPK) pathway activation in the mushroom body.
• Assessment of memory retention and resistance to disruption (heat shock, electric shock, odor reactivation).
• Investigation of Rac1 and non-muscle myosin II activity.
• Monitoring of presynaptic structural changes.

Main Results:

• Learning-activated MAPK signaling in the mushroom body γ lobe prolongs labile memory retention.
• Increased MAPK activity enhances memory resistance to various disruptive stimuli.
• Rac1 inhibition does not prevent forgetting; protection correlates with non-muscle myosin II activity and sustained presynaptic changes.
• Combined increased Raf/MAPK and suppressed Rac1 activity completely blocks labile memory decay.

Conclusions:

• Learning initiates an active protection mechanism for labile memory in Drosophila.
• This protection involves MAPK signaling and Rac1-independent pathways, regulating memory stability.
• Learning dynamically regulates memory through both active protection and active forgetting.