1 1 State - dependent sensorimotor processing : 2 gaze and posture stability during simulated flight in birds 3 4 Kimberly

24 25 Vestibular responses play an important role in maintaining gaze and posture stability 26 during rotational motion. Previous studies suggest that these responses are state-dependent, their 27 expression varying with the environmental and locomotor conditions of the animal. In this 28 study, we simulated an ethologically relevant state in the lab in order to study state-dependent 29 vestibular responses in birds. We used frontal airflow to simulate gliding flight and measured 30 pigeons’ eye, head, and tail responses to rotational motion in darkness, under both head-fixed 31 and head-free conditions. We show that both eye and head response gains are significantly 32 higher during flight, thus enhancing gaze and head-in-space stability. We also characterize state33 specific tail responses to pitch and roll rotation that would help to maintain body-in-space 34 orientation during flight. These results demonstrate that vestibular sensorimotor processing is 35 not fixed but depends instead on the animal’s behavioral state. 36 37