Zebrafish larvae display a robust startle response. Because this is mediated by neural pathways in a way similar to the process in higher vertebrates, startle response testing can be applied to a wide range of neuro-scientific studies.
The startle response can be evoked in different ways, such as via a light stimulus or a vibration stimulus. The former is already included in the DanioVision chamber, and for the latter, Noldus recently designed the DanioVision Tapping Device. This is a small instrument that can be placed into the DanioVision Observation Chamber, at the bottom of the basin where your well plate or petri dish is placed.
Tapping device for vibration stimulus at different levels
Taps from this device cause vibrations in the water, evoking a startle response in your animals. You can set the stimulus intensity at different forces – there are 8 levels – with a higher force resulting in more water movement. You can also adjust the tapping rate to a maximum of 3 taps per second. The Tapping Device can be combined with the white light stimulus, and both are controlled via the EthoVision XT software that is included in the DanioVision system.
To analyze the startle response of your animal, you can use the distance moved parameter that is measured by EthoVision XT to compare the periods before and after the stimulus.
No effect of location in the well plate
The Tapping Device provides an even stimulus for all animals tested. Beta testing showed no difference in response rate between animals in top versus bottom rows or in 96- versus 48-well plates.
Beta testing also showed that the startle response can be detected from the age of 3 to 9 dpf, for all stimulus intensities. Tests carried out on 5 and 6 dpf larvae showed no significant differences in the degree of response between days 5 and 6 (ANOVA, P >0.5).
*We acknowledge the kind collaboration of the following researchers and their groups: Dr. Stefan Spulber, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden; Dr. Edor Kabashi, Insitut du Cerveau et de la Moelle, Paris, France; Dr. Hiroko Nakatani, URM INSERM 788, Le Kremlin-Bicêtre, France.