'How Flies Control How They Walk by Knowing When and How to Stop'

What a catchy title for a seminar: "How Flies Control How They Walk by Knowing When and How to Stop."

Meet Salil Bidaye, Research Group Leader, Max Planck Florida Institute for Neuroscience, Jupiter, Fla.

He studies neuronal control locomotion in fruit flies, Drosophila--focusing his research on "understanding how fast and precise locomotor decisions are executed at the level of genetically defined neural circuits."

He will present his seminar, hosted by the UC Davis Department of Entomology and Nematology (ENT), at 4:10 p.m., Monday, March 4 in 122 Briggs Hall and on Zoom. The Zoom link:
https://ucdavis.zoom.us/j/95882849672.

Molecular geneticist and physiologist Joanna Chiu, professor and chair of the ENT department, will introduce him.

"Walking is a complex motor program involving coordinated and distributed activity across the brain and the spinal cord," Bidaye writes in his abstract. "Halting appropriately at the correct time is a critical but often overlooked component of walking control. While recent studies have delineated specific genetically defined neuronal populations in the mouse brainstem that drive different types of halting, the underlying neural circuit mechanisms responsible for overruling the competing walking-state neural activity to generate context-appropriate halting, remain unclear. Here, we elucidate two fundamental mechanisms by which I implement context-appropriate halting."

"The first mechanism ('walk-OFF' mechanism) relies on GABAergic neurons that inhibit specific descending walking commands in the brain, while the second mechanism ('brake' mechanism) relies on excitatory cholinergic neurons in the nerve-cord that lead to an active arrest of stepping movements," he explains. "Using connectome-informed models and functional studies, we show that two neuronal types that deploy the 'walk-OFF' mechanism inhibit distinct populations of walking-promotion neurons, leading to differential halting of forward-walking or steering. The 'brake' neurons on the other hand, override all walking commands by simultaneously inhibiting descending walking promoting pathways and increasing the resistance at the leg-joints leading to an arrest of leg movements in the stance phase of walking. We characterized two ethologically relevant behavioral contexts in which the distinct halting mechanisms were used by the animal in a mutually exclusive manner: the 'walk-OFF' pathway was engaged for halting during feeding, and the 'brake' pathway was engaged for halting during grooming. To our knowledge, this represents the first mechanistic understanding of halting in fruit-flies and hence a major step in our larger goal of uncovering the fundamental principles governing walking control in animals."

Bidaye accepted his Research Group Leader position at the Max Planck Florida Institute for Neuroscience in April 2021. He previously served as a postdoctoral Fellow at UC Berkeley in the lab of Professor Kristin Scott. He obtained his Ph.D. at the Research Institute of Molecular Pathology, Vienna, Austria, working in the Barry Dickson laboratory. 

While a graduate student in Vienna, "I observed fruit-flies chasing each other during courtship," he relates. "I got hooked on to the intricate control that comprises insect walking. "This fascination kindled by powerful fly genetic tools, has led me to persistently device new behavioral assays and neural recording techniques, aimed at elucidating the fundamental control mechanisms that underlie the exquisite locomotor control that is commonplace in all animals."

His publications include: 

• Two Brain Pathways Initiate Distinct Forward Walking Programs in Drosophila, Aug. 20, 2020, journal Neuron
• Six-Legged Walking in Insects: How CPGs, Peripheral Feedback, and Descending Signals Generate Coordinated and Adaptive Motor Rhythms, February 2018, Journal of Neurophysiology
• Neuronal Control of Drosophila Walking Direction, April 4, 2014, Science

Bidaye's seminar is expected to be the last of the winter quarter; the next scheduled speaker, Inga Zasada, a research plant pathologist with the USDA-ARS Horticultural Crops Research Laboratory, Corvallis, Ore., recently canceled her March 11 seminar due to a medical issue in the family.

For any Zoom technical issues, contact seminar coordinator Brian Johnson, associate professor, at brnjohnson@ucdavis.edu. The list of winter quarter seminars is here.