The startle response in fish is a pattern of rapid contractions of the axial musculature used for swimming elicited by external stimuli. In zebrafish (Danio rerio), it has long been employed for analyses of motor function, sensory physiology and basic forms of learning (e.g., Kimmel et al., 1974).
In developing zebrafish, the startle response can be quantified from day four post fertilization onwards by monitoring a larva’s locomotor activity in response to vibratory stimulation (VIDEO 1, Courtesy of Rodrigo J. De Marco, Max Planck Institute for Medical Research, Heidelberg, Germany). The Zantiks MWP unit allows measuring the activity of multiple larvae and also control graded vibratory stimulations caused by highly-controllable actions by a stepping motor.
VIDEO 1 showing startle response of larval zebrafish. Courtesy of Rodrigo J. De Marco, Max Planck Institute for Medical Research, Heidelberg, Germany
Experimental set up
Larval zebrafish are placed individually in each well of a 6, 12, 24 48 or 96 well plate.
The multi-well plate with the larvae is inserted into the chamber of the Zantiks MWP unit, and the script is set up to control illumination level (complete darkness in this case), vibratory stimulation (state variables of the motor rotations causing reproducible water motions inside each well) and the locomotor activity of each larva (generally measured in arbitrary units or as swum distance), which is written to a data file at whatever frequency is required by the experimenter – 1 second bins are often used.
Video (speed, 8x) of zebrafish larvae in a 24 well plate before, during and after a single pulse of mild vibratory stimulation. The red dot in the top right hand side of the video frame depicts when the vibration occurs.
Figure depicting average locomotor activity over time in response to vibratory stimulation (FIGURE 1).
Kimmel C. B., Patterson J., Kimmel R. O. (1974). The development and behavioral characteristics of the startle response in the zebra fish. Dev. Psychobiol. 7, 47–60. 10.1002/dev.420070109