Drosophila DPM neurons form a delayed and branch-specific memory trace after olfactory classical conditioning

Area of Science:

• Neuroscience
• Molecular Biology
• Animal Behavior

Background:

• Olfactory memory formation is essential for survival and involves complex neural circuits.
• The amnesiac gene and dorsal paired medial (DPM) neurons have been implicated in memory, but their precise roles are not fully understood.

Purpose of the Study:

• To investigate the role of the amnesiac gene in DPM neurons during olfactory memory formation.
• To characterize the cellular and temporal dynamics of memory trace formation in DPM neurons.

Main Methods:

• In vivo calcium imaging of DPM neuron activity in response to odor and electric shock stimuli.
• Genetic manipulation to assess the requirement of the amnesiac gene in DPM neurons.
• Electrophysiological recordings to measure synaptic release from DPM neurons.

Main Results:

• DPM neurons exhibit odor-evoked calcium signals and increased synaptic release upon pairing odor with electric shock.
• Memory trace formation is localized to a specific branch of the DPM neuron process.
• The amnesiac gene is essential for the formation and persistence of these cellular memory traces.
• Cellular memory traces emerge 30 minutes post-conditioning and last for at least 1 hour.

Conclusions:

• DPM neurons act as "odor generalists" by responding to various odors.
• A delayed, branch-specific, and amnesiac-dependent memory trace is formed in DPM neurons.
• This cellular trace is critical for normal olfactory memory recall and may guide subsequent behavior.