RoL: FELS: EAGER: Collaborative Research: Exceptions that Test the Rules - Establishing the Feasibility of Avian Feather Muscles as a Study System for Neuromotor Control

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Nearly all of what is understood about how animals control their movement comes from studies of skeletal muscle under the control of the somatic motor branch of the nervous system - the same kinds of structures that allow humans to walk, grasp objects, and speak. In addition to these systems, animals also control movement with smooth muscle, under the control of the autonomic motor branch of the nervous system - these are the muscles that allow people to sweat, blush, get goosebumps, and move food through the gut. While these are generally considered "low-level" tasks that do not require complex control, birds use autonomic control of smooth muscle in the skin to position feathers for display, and even to control the position of wing feathers in flight. Both of these tasks demand complex integration with other movements. This Rules of Life proposal tests whether there are evolutionarily convergent control systems for smooth muscle and skeletal muscle motor control in bird. The major obstacle to understanding how smooth muscles work in birds is technical. The existing techniques to measure and control skeletal muscle activity cannot be used on smooth muscles. This project will test the use of fiber-optic technology and drug interventions to measure and manipulate smooth muscle function in awake, behaving birds. Investigating the control of smooth muscle in birds can provide a new window into muscle activity. The broader implications of the work extend to the design of control systems, for example those of unmanned autonomous vehicles. In addition to basic research, this project includes teacher training workshops that bring the biology and technology involved into high-school classrooms.The overall objective of this project is to develop methods for recording and manipulating feather muscle activation in vivo. The rationale is that the ability to assess feather muscle activity will open an entirely untapped pool of complex smooth-muscle motor behaviors for comparison to striated-muscle systems. The overall objective will be attained by pursuing two specific aims. First, fiber-optic approaches to record feather muscle activity will be tested in vivo. Smooth muscle activity can currently only be measured reliably in vitro. This set of studies tests the feasibility of fiber photometry with Ca2+-sensitive fluorescent dyes to record the intracellular Ca2+ signaling events that drive muscle contraction in vivo. Second, the molecular basis for modulation and manipulation of feather muscles will be evaluated. Visceral smooth muscles (e.g., wall of gastrointestinal tract) exhibit several pathways that control contractile state, some of which are known to be shared with feather muscles. This set of studies will use expression proteomics to determine the extent of differences in control pathways between feather musculature and visceral smooth muscle, then test indicated control pathway inhibitors to reveal which pathways can be used for targeted manipulation of feather muscle function in vivo.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.