Knowledge Base

Introduction

Larval stage zebrafish display a robust startle response, which is mediated by neural pathways similar to that in higher vertebrates. With the DanioVision Tapping Device you can evoke a startle response in zebrafish larvae.

How the Tapping Device Works

The DanioVision Tapping Device is based on an electromagnetically inductive coil wound around a metal core. The core is made of two parts, a fixed one and a plunger connected to a push pin. When a current flows in the Tapping Device, magnetic force is created between the plunger and the core, causing the plunger and the push pin to quickly move forward. The pushpin hits a metal plate attached to the basin in which the well plate is kept. When deactivated, a spring makes the plunger resume its position.

How You Control the Tapping Device

With the Trial and Hardware Control module of EthoVision XT you can plan when to activate the Tapping Device during a trial. For example, activate the Tapping Device 10 times at intervals of two minutes.

Noldus Test Results: A Summary

• In both light and dark conditions, the Tapping Device is capable of inducing a startle response in animals of 3 dpf and older.
• It is in principle possible to design experiments where the animals are subject to stimuli of different intensity. You can set the tap intensity in EthoVision XT.
• There is no evidence that the startle response measured by EthoVision XT depends on light conditions and location of the subject in the well plate.

See also the white paper Using the DanioVision Tapping Device, which you can download from our web site.

Important: We advise you not to compare the results between two DanioVision Observation Chambers provided with the Tapping Device. Slight differences in the position of the Tapping Device may result in differences in the actual stimulus intensity, all else being equal.

Install the DanioVision Tapping Device

If you order the Tapping Device together with a DanioVision Observation Chamber, the Tapping Device is already installed. In all other cases:

1. Open the lid of the DanioVision Observation Chamber, and remove the bench plate.
2. Remove the two bolts from the aluminium plate at the bottom of the chamber. Make sure that the backlight box does not move.

   Tip: Use a pencil to mark the exact position of the backlight box on the frame so that you can place it in that position if it accidentally moves.

3. Put the metal frame of the Tapping Device over the aluminium profiles, and fix the bolts with the supplied spring washers. Use both the already connected spring washers and the new ones.
4. Connect cables as indicated:
   • a — The cable with a 4-pin white connector comes from the Tapping Device.
   • b — The flat cable with a blue connector comes from the bottom of the DanioVision chamber. Raise the metal hooks, insert the connector, then lower the hooks to fix the connector.
   • c — The cable with 2-pin connector comes from the bottom of the DanioVision chamber.
5. Attach the control box to the aluminium profile at the front side of the observation chamber.
   • a — Insert the screw in one of the holes at the sides of the control box.
   • b — Attach the spacers and the sliding nuts to the screw.
   • c — Insert the sliding nuts into the profile, and turn the screw.
6. Put the bench plate back into place and fix the four screws.

Set Up the Tapping Device in EthoVision XT

Make sure that the DanioVision Observation Chamber is connected to your EthoVision XT computer.

Experiment Settings

Under Trial Control Hardware, click Settings. In the Hardware Interface window, select DanioVision DVOC-004x/T.

Arena Settings

Note: If you created an experiment with a pre-defined template and selected an arena template for DanioVision with the Tapping Device (DanioVision DVOC 004x/T), the Tapping Stimulus has been assigned automatically to the arenas. The steps below are then not necessary.

1. In the Arena Settings pane click Arena - Hardware Mapping and then click the Arena - Hardware Mapping button.
2. Click Add Device. Under Device Type, select Tapping Stimulus. Under Arena 1 select Tapping Stimulus.
3. To test the Tapping Device, select the cell under Arena 1 and click Test.

Trial and Hardware Control Settings

1. Open the Trial Control Settings containing the protocol in which you want to insert the Tapping Stimulus. Under Actions - Hardware click the button next to Tapping Stimulus.
2. In the Hardware Action window specify the Intensity Level (1–8). Click Test to get an impression of the tap intensity.
3. Click OK and insert the Action box in your Trial Control protocol.
4. Test the protocol before carrying out the real trials.

Important: Allow at least 300 milliseconds between two consecutive tapping events. To do so, place a Time Condition box that specifies this time between two Tapping Stimulus Action boxes.

Analyze the Response to the Tapping Stimulus

You can analyze the startle response by looking at dependent variables like Activity, Distance Moved, or Acceleration (State) immediately before and after the administration of the stimulus.

In the following example, we examine the Total Distance Moved in the 1-second periods immediately before and after the tapping stimulus command was given. We expect that the total distance moved increased from "before" (assumed to be a baseline) to "after". The stimulus command was given at exactly 1 minute after the start of the trial.

1. In the Data profile define two Nesting time intervals, one from 00:59.00 to 01:00.00, the other from 01:00.00 to 01:01.00. Each of the resulting Nest boxes is connected to a separate Results box.
2. In the Analysis profile define Distance Moved.

Source: DanioVision DVOC-0041 Reference Manual, Noldus Information Technology