Moving animals often use vision to determine where they are and where they are going. However, the scene in an animal's eyes only makes sense if it knows its own body position and movements. While they are moving, animals can also predict how their senses will be affected by their own movements. For example, as a human walks, his eyes bounce up and down with his steps, but he does not see this motion because his brain predicts and ignores this self-generated visual information. Though much is known about how this process works in a single sense organ, less is known about how multiple senses work together to do this. In many animals, the inner ear monitors the position and movement of the body. However, the inner ear is inside the head and difficult to study and manipulate. This project will take advantage of animals with rotation sensors on the outside of their bodies to observe how these organs influence behavior. In flies, specialized organs called halteres detect body movements and these structures are located outside the body near the wings. This research will measure changes in fly behavior that occur when the sensory information coming from the haltere is changed and when it does not match information gathered through vision. This work will show how multiple senses are integrated with the animal's own behavior to guide movement. By examining how the brain combines multiple sensory inputs and anticipates the consequences of its own behaviors, this work will uncover mechanisms of the brain's function that can be applied to other species and that can be used to understand biological brains and engineer algorithms for moving machines. The project will also be incorporated into a series of workshops at an all-girls high school with the goal of improving quantitative and computer coding skills in female students.
Distinguishing between self-generated and externally generated body movements is a central challenge for the nervous system. Efference copy, a neural signal of opposite sign to expected sensory input, is a possible mechanism for this distinction. Efference copies have been observed in single sensory systems, but how might they function in a multi-sensory context? Using an animal with a well-understood visual system and an easily-accessible mechanosensory organ, these experiments will investigate how these two sensory modalities combine during voluntary and involuntary movements. In flies, body rotations are detected by specialized mechanosensors called halteres. These are modified hindwings that perform a function similar to the mammalian vestibular system. This project will investigate the integration of haltere information, visual information, and motor commands through quantitative behavioral analysis of flying flies. Flies will fly under different conditions: flight with imposed body rotations (tethered to a motor), flight with free, self-generated rotations (tethered to pins suspended between magnets), and rigidly tethered flight (no body rotations) with imposed movements of the haltere. The fly's head movement behavior will be observed under these conditions, and the behavior of intact flies will be compared to flies with their mechanosensory halteres removed or manipulated. Finally, information theoretic analysis will be used to quantify the flow of information in the visual and mechanosensory systems and construct a theoretical framework that can be used to understand how information about body rotations is integrated with visual information to control posture and gaze. Taken together, these experiments and model will demonstrate how two sensory modalities are combined and integrated with motor feedback during flight. Broader impacts include workshops to broaden experience for young women in quantitative and computer coding skills and presentation of the work to various non-scientific audiences. Work completed here has application to the field of robotics and the development of higher quality autonomous aerial robotics.
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.
