scholarly journals Inhibitory muscarinic acetylcholine receptors enhance aversive olfactory conditioning in adult Drosophila

2018 ◽  
Author(s):  
Noa Bielopolski ◽  
Hoger Amin ◽  
Anthi A. Apostolopoulou ◽  
Eyal Rozenfeld ◽  
Hadas Lerner ◽  
...  
Keyword(s):  
Mushroom Body ◽  
Acetylcholine Receptors ◽  
Physiological Function ◽  
Muscarinic Acetylcholine Receptors ◽  
Kenyon Cell ◽  
Olfactory Conditioning ◽  
Muscarinic Acetylcholine ◽  
Kenyon Cells ◽  
Output Neurons ◽  
Adult Drosophila

AbstractOlfactory associative learning inDrosophilais mediated by synaptic plasticity between the Kenyon cells of the mushroom body and their output neurons. Both Kenyon cells and their inputs are cholinergic, yet little is known about the physiological function of muscarinic acetylcholine receptors in learning in adult flies. Here we show that aversive olfactory learning in adult flies requires type A muscarinic acetylcholine receptors (mAChR-A) specifically in the gamma subtype of Kenyon cells. Surprisingly, mAChR-A inhibits odor responses in both Kenyon cell dendrites and axons. Moreover, mAChR-A knockdown impairs the learning-associated depression of odor responses in a mushroom body output neuron. Our results suggest that mAChR-A is required at Kenyon cell presynaptic terminals to depress the synapses between Kenyon cells and their output neurons, and may suggest a role for the recently discovered axo-axonal synapses between Kenyon cells.

scholarly journals Inhibitory muscarinic acetylcholine receptors enhance aversive olfactory learning in adult Drosophila

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Noa Bielopolski ◽  
Hoger Amin ◽  
Anthi A Apostolopoulou ◽  
Eyal Rozenfeld ◽  
Hadas Lerner ◽  
...  
Keyword(s):  
Synaptic Plasticity ◽  
Mushroom Body ◽  
Acetylcholine Receptors ◽  
Olfactory Learning ◽  
Muscarinic Acetylcholine Receptors ◽  
Projection Neurons ◽  
Kenyon Cell ◽  
Muscarinic Acetylcholine ◽  
Kenyon Cells ◽  
Output Neurons

Olfactory associative learning in Drosophila is mediated by synaptic plasticity between the Kenyon cells of the mushroom body and their output neurons. Both Kenyon cells and their inputs from projection neurons are cholinergic, yet little is known about the physiological function of muscarinic acetylcholine receptors in learning in adult flies. Here, we show that aversive olfactory learning in adult flies requires type A muscarinic acetylcholine receptors (mAChR-A), particularly in the gamma subtype of Kenyon cells. mAChR-A inhibits odor responses and is localized in Kenyon cell dendrites. Moreover, mAChR-A knockdown impairs the learning-associated depression of odor responses in a mushroom body output neuron. Our results suggest that mAChR-A function in Kenyon cell dendrites is required for synaptic plasticity between Kenyon cells and their output neurons.

scholarly journals Reciprocal synapses between mushroom body and dopamine neurons form a positive feedback loop required for learning

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Isaac Cervantes-Sandoval ◽  
Anna Phan ◽  
Molee Chakraborty ◽  
Ronald L Davis
Keyword(s):  
Nicotinic Acetylcholine Receptors ◽  
Positive Feedback ◽  
Mushroom Body ◽  
Acetylcholine Receptors ◽  
Critical Role ◽  
Olfactory Learning ◽  
Dopamine Neurons ◽  
Olfactory Conditioning ◽  
Kenyon Cells ◽  
Presynaptic Calcium

Current thought envisions dopamine neurons conveying the reinforcing effect of the unconditioned stimulus during associative learning to the axons of Drosophila mushroom body Kenyon cells for normal olfactory learning. Here, we show using functional GFP reconstitution experiments that Kenyon cells and dopamine neurons from axoaxonic reciprocal synapses. The dopamine neurons receive cholinergic input via nicotinic acetylcholine receptors from the Kenyon cells; knocking down these receptors impairs olfactory learning revealing the importance of these receptors at the synapse. Blocking the synaptic output of Kenyon cells during olfactory conditioning reduces presynaptic calcium transients in dopamine neurons, a finding consistent with reciprocal communication. Moreover, silencing Kenyon cells decreases the normal chronic activity of the dopamine neurons. Our results reveal a new and critical role for positive feedback onto dopamine neurons through reciprocal connections with Kenyon cells for normal olfactory learning.

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