The kinematics and conservation of motor patterns in larval zebrafish, Danio rerio

Abstract

The zebrafish has become a model organism with which to investigate sensorimotor integration and the organization of motor control systems. The ultimate goal of such research is to understand the cellular basis of motor acts including locomotor behaviors. Quantitative kinematic analysis, and focus upon the physical maneuvers that comprise locomotor behaviors, should enhance the utility of the zebrafish model. The larval zebrafish exhibits two distinct forward swimming patterns: a slow swim and a burst swim. These swimming patterns differ in terms of tail-beat frequency, bend angle, bend location and swim velocity. Using a high-speed camera, we analyzed the motor patterns exhibited by larval zebrafish in response to whole-field illumination changes and during rheotaxis and optomotor behaviors. These behaviors were compared to the slow and burst swimming patterns, and based on a variety of measurements, we conclude that a conserved slow swim motor pattern is used during diverse navigational behaviors. While certain kinematic variables, such as tail-beat frequency, bend amplitude and slip may vary to adjust swim speed and position in the environment, the similarities in the kinematic features suggest a common premotor circuit that can be stimulated by diverse sensory inputs. Conserved movement patterns were also used during diverse navigational turning behaviors, including the optomotor and dark-evoked turns. All of these locomotor patterns appeared to employ a ""slow"" motor system that is distinct from the high-frequency, short latency motor system used during larval C-start escape behaviors.