Knowledge Base

Prepare a List of Trials (Optional)

In EthoVision XT, a Trial is an uninterrupted recording session. The Trial List is a table listing the trials planned for an experiment. When you create a new experiment, a few planned trials are already present.

To Add More Trials

1. Choose Setup > Trial List. Click the Add Trials button.
2. Type the number of trials you plan to carry out and click OK.
3. For each row:
   • Specify the independent variables (optional; see the next section).
   • Specify which video file you want to use (when tracking from video files).
   • Select Arena Settings, Trial Control Settings, and Detection Settings (optional). If those columns are not present in the Trial List, click the Show/Hide button, click Variables and select them.

Note: Planning your trials in advance also allows you to acquire trials in batch mode. See Trial List in the EthoVision XT Help.

Independent Variables

What Are Independent Variables?

Independent variables are either simple descriptive categories (such as the genotype or age of your rats or mice), or conditions manipulated by the researcher (such as the substance being tested and the dosage). You can use independent variables to create analysis groups or filter data. For example:

• Compare tracks of treated subjects with tracks of control subjects.
• Only analyze subjects of a specific age class.

Note: If you created a template experiment, one or more independent variables have been predefined in your Trial List. For instance, Animal ID and Treatment.

To Define an Independent Variable

1. Choose Setup > Trial List.
2. Click the Add Variable button. A new column appears on the right of the table.
3. Specify the Label (for example: Dose), Description, Type (for example, Text or Numerical), Format, Predefined values (for example, 0.01, 0.02 etc. mg/kg), and Scope (whether the values of the variable differ between subjects within the same arena, between arenas within the same trial, or between trials).

Acquire the Data

Methods

Choose Acquisition > Open Acquisition. Locate the Acquisition Settings window at the right side of the screen.

• If you track from pre-recorded video files, select Track next planned trial, click the button next to Video and open the video you want to use.
• If you track from the live camera image, select Track next planned trial. Select Save video if you want to save the camera footage to a video file.

For more acquisition methods, see Acquire Data in the EthoVision XT Help.

Procedure for Acquiring One Trial

1. Under Settings, choose the Arena Settings, Trial Control Settings, and Detection Settings, if they are not already selected in the Trial List.
2. If you track from video and do not score behaviors manually, make sure the DDS (Detection Determines Speed) checkbox is selected in the Playback Control window. With this option you ensure that every sample is analyzed.
3. To start a trial, click the Start trial button in the Playback Control window.
4. Release the subject in the arena.
5. To stop the trial, click the Stop trial button.
6. Return the subject to its home cage or container.
7. Prepare the next subject, or load a new video file to acquire the next trial.

More Options

• You can automatically start and stop your trial depending on the behavior or position of your subject. See the Trial Control Settings section for details.
• You can also acquire data in batch mode. For details, see Batch data acquisition in the EthoVision XT Help.
• You can also score behaviors manually during tracking. If you saved the video during tracking, you can review the video and add or edit existing behavioral data. For details, browse the EthoVision XT Help:
  • To define behaviors, see Set Up an Experiment > Manual Scoring Settings.
  • To score behaviors, see Acquire Data > Score behaviors manually.
• If no planned trial is left, click the Add Trial button in the Playback Control window.
• Note: Sometimes EthoVision XT tracks a reflection instead of the subject, it confuses the nose-point and the tail-base or swaps subjects when you track multiple animals simultaneously. Whenever that occurs, you can correct those errors. For more information, see Edit the Tracks in the EthoVision XT Help.

Calculate the Statistics

Prepare the Tracks

A track is the group of samples acquired for a subject. You can choose to smooth the tracks to get a more reliable measure of the animal's movement path and remove the effect of outliers (caused by accidental wrong detection), random noise and body wobble.

1. Choose Acquisition > Track Smoothing Profile. Select Open and click OK.
2. Select one or more of the options: Smoothing (Lowess), Minimal Distance Moved and Maximum Distance Moved.

For information on the smoothing options, see Smooth the Tracks in the EthoVision XT Help.

Analysis Profiles

Choose Analysis > Analysis Profile. Select New, name the analysis profile and click OK.

Distance moved and Velocity are predefined as dependent variables. To add a variable to the Analysis profile, click the button next to that variable.

Note: If you created the experiment from a template, it contains a few analysis profiles. For example, the Morris water maze template experiment with the platform zone template contains four analysis profiles. One of them, Latency to reach platform, contains the variables for calculating the time taken to reach the platform.

Basic Calculations

Total Distance Moved or Average Velocity

1. Open the Analysis profile.
2. If the variable is not yet listed under Selected Dependent Variables, click the button next to Distance moved or Velocity. In the Trial Statistics tab, select Total for Distance moved, or Mean for Velocity.
3. Choose Analysis > Results > Statistics and Charts.

Time in a Zone and Number of Zone Entries

In step 2 above, click the button next to In zone. Specify the zone. In the Trial Statistics tab, select Cumulative duration and Frequency.

Source: EthoVision XT 19 - Quick Start Guide