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Open Access Publications from the University of California

Motor Neurons Controlling Fluid Ingestion in Drosophila melanogaster

  • Author(s): Manzo, Andrea
  • Advisor(s): Scott, Kristin
  • et al.

How environmental stimuli are detected and processed by the brain to produce a behavioral output remains a central question in neurobiology. The gustatory system in Drosophila is an excellent model for studying this problem as flies possess strong innate behaviors to many taste stimuli and can be studied using a variety of molecular and genetic tools. Because of these advantages, it should be possible to assemble a complete anatomical and functional map of the neurons mediating taste perception and behavior.

In Drosophila , taste compounds are detected by sensory neurons that send axons into the brain. Second- and higher-order neurons in the gustatory circuit have not yet been identified. In the first part of my thesis, I describe the results of an inducible activation screen to identify neuronal populations whose activity is sufficient to elicit proboscis extension. This screen led to the identification of motor neurons that control pumping behavior.

In the second part of my thesis, I describe my work studying motor neurons that innervate the proboscis musculature of Drosophila. These neurons drive a pump that draws fluid into the esophagus during feeding. My results show that these motor neurons are necessary for normal pumping and ingestion to occur, and that their activity is sufficient to elicit pumping. Furthermore, my data suggests that these neurons are not just passive effectors of a pumping circuit but play a role in generating the pumping rhythm.

In the third part of my thesis, I describe a population of neurons whose morphology suggests they may receive input from sensory taste neurons. They project from the taste region of the fly brain to higher order regions that have not been well-described. The results of my experiments showed that these neurons do contact sensory taste neurons, but are not required for normal gustatory learning. Future experiments will help determine if they play a role in the processing of gustatory information.

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