Knowledge Base

Experiment Setup

Create an experiment. For details, see Chapter 1 of this manual, or in EthoVision XT press F1 and see Setup an Experiment in the EthoVision XT Help.

For suggestions about optimizing lighting, see the lighting optimization section of this manual.

Experiment Settings

Choose Setup > Experiment Settings.

• Number of Subjects per Arena: 1
• Tracked Features: Center-point detection or center point, nose-point and tail-base detection.

If you want to use the Deep Learning technique to track the subject's nose, under Body Point Detection Technique choose Deep Learning. Note that in order to use this technique there are additional requirements. Among other things, you need a powerful graphics card. See Deep Learning: Requirements and Limitations in the EthoVision XT Help.

Arena Settings

For the Spontaneous Alternation Task

1. Choose Setup > Arena Settings > Open Arena Settings 1.
2. Choose the video/camera image and click Grab.
3. Click 2. Select Shape and Draw Arena. Resize and move the outline of the arena to make it overlap with the Y-maze image.

For details on how to resize and move the arena outline, see Arena Settings in the EthoVision XT Help.

For the Delayed Alternation Task

Choose Setup > Arena Settings > New.

After calibrating and drawing the outline of the arena, click 3. Select Shape and Draw Zones. Draw the three arm zones. To draw the start box zone and the target zones (that is, the arm ends which will be baited with food), create an additional zone group.

For details on how to work with zone groups, and draw and edit shapes, see Arena Settings in the EthoVision XT Help.

Trial Control Settings

In the Trial Control Settings you can define conditions for the start and stop of data acquisition.

Choose Setup > Trial Control Settings > New.

The templates for the Y-maze contain the following Trial Control Settings profiles:

• Default: Tracking starts when the subject's center point is detected for 1 second in the arena. Tracking stops at the end of the video or when you give the stop command.
• Tracking Duration 5 min: Tracking starts when the subject's center point moves from the start box to the center arm. Tracking stops after 5 minutes.

Detection Settings

Choose Setup > Detection Settings.

Check in the Video Section that the sample rate is set to:

• Rats: 5 samples/second
• Mice: 12.5–15 samples/second

However, when tracking the nose-point, center-point and tail-base point of the rodents, always choose the maximum sample rate.

If you selected the Deep Learning technique to track the subject's nose, under Method next to Deep Learning click Define and select a box around the subject. Make sure that the box includes the subject's nose. Try not to include objects like walls, especially if they are the same color as the subject. For details, see the EthoVision XT Help.

Trial List

Independent Variables

If you perform a Y-maze test where one of the arms is closed off or provided with food, it is always a good idea to create independent variables that mark the type of trial. For example, create the independent variable Correct Choice with possible values Yes and No, depending on whether the subject chose the arm not visited in the previous trial. At the end of each trial, enter the value for that subject. You can use this variable to filter trials based on the value of Correct Choice.

Acquiring Data

Protocols

Continuous Spontaneous Alternation

1. Release the subject in the center of the Y-maze.
2. Start the trial.
3. Let the subject explore the maze for the time required (typically 5–6 minutes). Then stop the trial.
4. Put the subject back in its home cage. Proceed with the next subject.

Forced-Choice Alternation

In this variant, the subject is forced to explore one of the two arms in the first trial.

1. Close one of the arms of the maze. Place the subject into the start arm and allow it to explore the maze for 15 minutes.
2. After a fixed inter-trial interval, open the door in the blocked arm. Return the subject to the maze by placing it in the start arm. The subject is allowed to explore freely all three arms of the maze for 5 minutes. The Y-maze is often rotated between the two trials.

Two-Trial Spontaneous Alternation

In this task, the subject is confined for a fixed time in the T- or Y-maze arm chosen in the first trial. This allows manipulation of the time that the animal has experience with one of the arms.

1. In the first trial, let the subject access one of the arms after having left the start arm. Once an arm has been entered, close off that arm by lowering a guillotine door behind the subject. Leave the subject there for a fixed time (this is called the intra-trial interval).
2. Remove the subject and, after an inter-trial interval, let it choose the arm in a second trial. This two-trial sequence is repeated a number of times.

Delayed Alternation

This task is usually designed with a T- or Y-maze where one arm is the starting location and the other arms are baited.

1. Release the subject in the start arm. Once the subject enters one of the other two arms, close the door for that arm (trial 1).
2. After a predetermined inter-trial interval, release the subject and let it freely choose one of the two arms (trial 2).

If the subject chooses the alternate arm, this is scored as alternation. This two-trial procedure is repeated several times.

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