Activity and function of leg motor neurons in walking Drosophila

• Applicant: Dr. Chris Dallmann
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: from 2019 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 432196121

Although many of our movements seem effortless, they require extremely sophisticated neural control. Arm and leg movements result from muscle contractions that are driven by populations of motor neurons in the central nervous system. As the ultimate output of the nervous system, motor neuron activity is coordinated by circuits in the brain and spinal cord, which rely on sensory feedback from the limbs. However, how different motor neurons are recruited to meet the specific demands of a motor task and to what extent their recruitment relies on sensory feedback remains elusive. I propose to tackle these questions by studying the activity and function of leg motor neurons in tethered walking fruit flies (Drosophila melanogaster). Like humans and other animals, fruit flies coordinate their legs in a flexible manner during walking. By studying the model organism Drosophila, I will benefit from a relatively compact nervous system and the unparalleled ability to genetically target specific subsets of neurons. Based on previous studies, I will perform experiments to address two questions: 1) Do different types of motor neurons serve specific functions during walking, and 2) is the role of sensory feedback in tuning motor neuron activity dependent on walking speed? To answer these questions, I will combine two-photon functional imaging of motor neuron activity in the central nervous system, optogenetic manipulation, and markerless tracking of body and leg movements in flies walking on an omnidirectional treadmill. I will first determine how specific motor neurons are recruited in relation to walking speed and context. I will then test these relationships by optogenetically silencing motor neurons in different walking situations and quantifying the resulting effects on walking behavior. Finally, I will measure motor neuron activity and walking behavior while optogeneically manipulating sensory neurons that provide feedback about leg position and movement. By causally linking motor neuron activity to sensory feedback and walking behavior, I hope to obtain a better mechanistic understanding of how the nervous system controls movement.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor John Tuthill, Ph.D.