Synapsin determines memory strength after punishment- and relief-learning.

Area of Science:

• Neuroscience
• Molecular Biology
• Animal Behavior

Background:

• Adverse life events can form memories of both negative (punishment) and positive (relief) valence, depending on stimulus timing.
• These timing-dependent memory types are observed across species, including insects, rats, and humans.
• The molecular basis for these dual-valence memories remains largely unknown.

Purpose of the Study:

• To investigate whether timing-dependent punishment and relief memory share common molecular determinants.
• To examine the role of Synapsin, a presynaptic phosphoprotein, in these associative memory processes.

Main Methods:

• Utilized Drosophila melanogaster (fruit flies) for behavioral experiments involving forward (odor-shock) and backward (shock-odor) conditioning.
• Generated and analyzed Synapsin knockout and RNAi-mediated knockdown fruit fly models.
• Assessed memory scores and ruled out nonassociative processing, discrimination, and coincidence detection alterations.

Main Results:

• Synapsin deficiency did not affect basic sensory or motor functions but significantly reduced both punishment and relief memory.
• RNAi-mediated knockdown of Synapsin also impaired both memory types.
• Restoring Synapsin, either acutely or in mushroom bodies, rescued the memory deficits.

Conclusions:

• Synapsin protein is essential for both punishment memory and relief memory formation in fruit flies.
• These findings demonstrate shared genetic and molecular determinants for dual-valence associative memories.
• Understanding these common pathways could inform therapeutic strategies for human memory disorders, such as PTSD.