Meeting Abstract

P2.74  Monday, Jan. 5  Diversity in startle behavior of larval zebrafish BAILEY, IB*; GREEN, MH; HALE, ME; Univ. of Chicago ianb@uchicago.edu

Startle behaviors are important models for understanding simple circuits and how they generate movement. The major startle of fishes is the C-start, characterized by a C-shaped body bend during the initial rapid turn (stage 1). Recently, in esocid fishes, S-start startles, which have a caudal body bend to the opposite side of the body from the major rostral bend, have been shown to involve a different pattern of motor control from the C-start. We examine whether there is variation in the use of caudal bending in zebrafish, a species believed to perform only C-start behaviors. We recorded video (1000 Hz) of the startle behavior in five-day-old larval zebrafish. In other species studied, head stimulation tended to elicit C-starts whereas tail stimulation resulted in S-starts, so we used both stimuli to generate a range of behaviors. As in previous study, head stimuli produced greater head angles and durations than tail stimuli. At both two and four ms after initiation, peak rostral curvature did not differ between stimulus types, but peak curvature was more caudal when generated with tail stimuli. Caudal bending was generally to the opposite side of the body from the rostral bend but was significantly greater and more rostral in response to tail stimulation. The ranges of caudal bending to head and tail stimuli overlapped significantly, suggesting either there is a continuum of responses rather than discrete S-start and C-start bending patterns or that fish use both bending patterns in response to each stimulus type. These explanations will need to be tested with neurophysiological recordings. This investigation indicates more variability than previously believed in startles typically thought of as C-starts. Supported by NSF grant IBN0238464 to MEH.