Knowledge Base

Experiment in EthoVision XT

Automated Detection Setup

In the Detection Settings window, click Automated Setup. Draw a rectangle around each subject in the video image, and follow the instructions on the screen.

Minimize the Indentations Caused by the Grid

In the Detection Settings, click Advanced. Under Subject Contour, choose what follows depending on the color of the subject and the grid bars:

• If the grid bars are the same color as the subject, use the first Erosion filter. Increase the value near Erosion until the grid is no longer detected. Normally 2–3 pixels are fine. Check that the whole body is detected, indicated by the yellow blob.
• If the grid bars are of a color other than the subject, and the detected subject appears to be broken in multiple parts, use the Dilation filter. Increase the value near Dilation until the yellow body is entirely over the subject's body. After that, reduce the size of the yellow blob by means of the second Erosion filter.

For details, see Advanced Detection Settings: Subject Contour in the EthoVision XT Help.

Minimize the Effect of the Subject's Shadow

Make the contrast range smaller to exclude the pixels in the shadow. For example, if the subject has dark fur and the shadow is included in the yellow blob, then next to Dark, move the left slider to the right. This will exclude smaller values of contrast. You should see the yellow area over the shadow shrinking. EthoVision XT will not follow the shadow anymore.

Do this in small steps, until the shadow is no longer detected. Make sure that the whole body is still detected in all parts of the cage.

Tip: If the background looks too similar to the color of the subject, place a sheet of paper or plastic in the drawer that you find under the shock grid. Try to make as much contrast as possible between the subject and the background.

Set Activity Analysis for Freezing Detection

In the Detection Settings window, click Activity. Adjust the settings so that a large number of purple pixels appear only when the subject moves.

• If the Activity threshold is too low, purple pixels also appear in the background. Increase the value of Activity threshold until purple pixels appear only when the subject moves, such as when a mouse moves its head.
• If the Activity threshold is too high, purple pixels disappear completely. A sufficiently wide range of purple pixels is required in order to detect immobility (freezing).
• When the subject freezes, the number of purple pixels should be minimized.

For more information:

• See Activity Settings in the EthoVision XT Help.
• Click the video button next to Activity and watch the video tutorial.
• For details about the advanced detection settings, see Configure Detection Settings in the EthoVision XT Help.

Troubleshooting

All FCS Devices Are Listed for Arena 1 Only

This may have occurred when you selected the number of arenas after defining the COM ports for the FCS cages. If, at the time of defining the COM ports, the number of arenas was still 1, EthoVision XT assumes that all the devices must be associated with Arena 1.

Do the following:

1. In the Arena-Hardware Mapping window, select each row and click Remove Device. Do so to remove all the devices.
2. Choose Setup > Experiment Settings.
3. Under Trial Control Hardware, click Settings, then choose Ugo Basile F.C. Controller. In the window that opens, make sure that the COM ports are listed and click OK.
4. Under Number of Arenas, select the number of arenas you work with.
5. Choose Setup > Arena Settings and click the Arena-Hardware Mapping button. At this point the devices should be correctly selected under one of the arenas.

The IR Light Is Switched Off or Its Intensity Is Not Optimal

1. Create a new Trial Control Settings profile (Setup > Trial Control Settings > New).
2. Click the button next to Action - UB FCS IR Light.
3. Select the device from the UB FCS IR Light list.
4. Select Light ON and choose the Intensity Level (recommended: 100%).
5. Click Test, then OK.
6. Open the Detection Settings and verify that the chamber is illuminated.

Tip: Keep the new Trial Control Settings profile so you can always access it in case you want to restart the IR light. Do not use this profile for tracking.

Another way to restore the default IR light is to restart the cubicle (disconnect and then reconnect the power). See also Update the Cubicle Firmware to make sure that the default state of the IR light sets the default light intensity.

The Fan Is Switched Off

Restart the cubicle (disconnect and then reconnect the power).

Source: EthoVision XT 18 - Application Manual, Noldus Information Technology