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Published on: October 8, 2019
Two clusters of GABAergic ellipsoid body neurons modulate olfactory labile memory in Drosophila
Zhiping Zhang1, Xiaoting Li, Jing Guo
1State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100049, People's Republic of China.
Abstract:
In Drosophila, aversive olfactory memory is believed to be stored in a prominent brain structure, the mushroom body (MB), and two pairs of MB intrinsic neurons, the dorsal paired medial (DPM) and the anterior paired lateral (APL) neurons, are found to regulate the consolidation of middle-term memory (MTM). Here we report that another prominent brain structure, the ellipsoid body (EB), is also involved in the modulation of olfactory MTM. Activating EB R2/R4m neurons does not affect the learning index, but specifically eliminates anesthesia-sensitive memory (ASM), the labile component of olfactory MTM. We further demonstrate that approximately two-thirds of these EB neurons are GABAergic and are responsible for the suppression of ASM. Using GRASP (GFP reconstitution across synaptic partners), we reveal potential synaptic connections between the EB and MB in regions covering both the presynaptic and postsynaptic sites of EB neurons, suggesting the presence of bidirectional connections between these two important brain structures. These findings suggest the existence of direct connections between the MB and EB, and provide new insights into the neural circuit basis for olfactory labile memory in Drosophila.
Insights
The ellipsoid body (EB) modulates Drosophila olfactory memory by regulating labile memory components. Activating specific EB neurons suppresses anesthesia-sensitive memory (ASM), revealing new neural circuits for memory.
Area of Science:
- Neuroscience
- Animal Behavior
- Molecular Biology
Background:
- Olfactory memory in Drosophila is primarily associated with the mushroom body (MB).
- Dorsal paired medial (DPM) and anterior paired lateral (APL) neurons regulate middle-term memory (MTM) consolidation.
Purpose of the Study:
- To investigate the role of the ellipsoid body (EB) in olfactory middle-term memory (MTM) in Drosophila.
- To identify specific neuronal populations within the EB involved in memory modulation.
- To explore potential synaptic connections between the EB and MB.
Main Methods:
- Neuronal activation experiments targeting EB R2/R4m neurons.
- Assessment of learning index and anesthesia-sensitive memory (ASM).
- Identification of GABAergic neurons within the EB.
- GRASP (GFP reconstitution across synaptic partners) to visualize synaptic connections.
Main Results:
- Activation of EB R2/R4m neurons specifically eliminated anesthesia-sensitive memory (ASM), a labile component of MTM, without affecting the learning index.
- Approximately two-thirds of the investigated EB neurons are GABAergic and contribute to ASM suppression.
- GRASP revealed potential bidirectional synaptic connections between the EB and MB.
Conclusions:
- The ellipsoid body (EB) plays a crucial role in modulating olfactory labile memory in Drosophila.
- Specific GABAergic neurons in the EB are involved in suppressing anesthesia-sensitive memory (ASM).
- Direct synaptic connections exist between the mushroom body (MB) and EB, offering new insights into olfactory memory circuits.
