Knowledge Base

The Start-Stop Trial Rule (Continued)

Call a Sub-Rule

Sub-rules are subroutines of the Start-Stop trial rule. You can program EthoVision XT in such a way that a subset of Trial Control actions and conditions is called from a specific point in the Start-Stop trial rule. When this subset of instructions is finished (or repeated a number of times), the program resumes following the instructions of the Start-Stop trial rule.

1. Define a sub-rule.
2. In the Components pane, under Structures, click the button next to Sub-rule reference. Enter a name for the reference, and select the sub-rule you have defined.
3. Insert the reference box in the correct place in the Start-Stop trial rule.

You cannot define a sub-rule reference without defining the sub-rule first.

Examples of Start-Stop Trial Rules

Start Data Recording at a Specific Time

You want to start recording at a time you are not in the lab, for example at 23:00 h.

Delete the default Start track condition. Define a Time condition. Select At clock time and enter 23:00:00. Click OK and place the resulting box before the Start track box. Before leaving the lab, click the Start trial button to start the trial. The program waits till 23:00 to start data recording.

Start Data Recording with a Remote Control

For this you need:

• The USB-IO box PTIO-002x
• The TTL Port Tester PTTB-001x, which can be used as a remote control

Have EthoVision XT start tracking when you press the button on the TTL Port Tester. To do so:

1. Connect the TTL Port Tester to a TTL port of the USB-IO box. See The USB-IO Box and the Mini USB-IO Box.
2. In the Experiment Settings, define the TTL port for the TTL Port Tester. See Set the Port Connections and, when needed, assign devices to arenas.
3. In the Trial Control Settings, create a Condition based on the TTL Port Tester that becomes true when button 1 is pressed.
4. Place the condition box between the Start Trial box and the Start track box.
5. You can now use the TTL Port Tester as a remote control. Note that with this solution you must first click the Start trial button in EthoVision XT, which then waits for the button press.

Stop Data Recording After the Maximum Time Has Elapsed

Click Settings in the Condition box immediately before the Stop track box. Select After and enter the maximum time. Alternatively, instead of using a Time condition, you can also use the Maximum trial duration option.

Water Maze: Stop the Trial When the Animal Has Found the Platform

In the Arena Settings, make sure that the platform has been defined as a zone. In the Trial Control Settings, delete the default Stop track condition. Next, define an In Zone condition.

• If you want the program to stop recording as soon as the animal is over the platform, select Frequency as Statistic and choose >= 1. Click Settings and select the platform zone.
• If the animal sometimes swims over the platform without stopping, select Current duration and set the minimum time the animal must stay on the platform (for example, 3 seconds). Click Settings and select the platform zone.

Click OK and place the resulting box before the Stop track box.

Water Maze: Stop the Trial Either When the Rat Has Found the Platform, or After 60 Seconds

The Arena Settings and the condition In platform zone are similar to those in the example above. The condition subject swimming for 60 s can be translated to Time >= 60 s.

• A – Zone condition: The subject must be for at least 3 seconds over the Platform zone. Select Current duration >= 3s.
• B – Time condition: 60 s since the track started.
• C – "Any" operator box.

The track stops when either condition is met. The two conditions are combined with OR logic. This solution results in tracks of different duration: less than 60 s for the animals that found the platform, and 60 s for the others.

Tip: Instead of two Condition boxes in the example above, you can also define the In Zone condition box and set a Maximum Trial Duration.

Multiple Open Fields: Starting Tracking When the Subject Is Released

In this setup, four open fields are treated as separate arenas. You want to start acquisition when the animal is detected in the open field, independently of what happens in other arenas. This can be achieved by using the default Start-Stop trial rule. As soon as the subject is detected in an arena, tracking starts for that arena only. This way you do not have to release all the animals at the same time.

Conditioning Test: Stop the Trial When the Conditioning Task Has Been Repeated N Times

For example, when the animal has obtained 25 rewards:

1. Create a new sub-rule containing the instructions for the testing session:
   • Sub-rule Begin
   • Condition: Is subject on top of the shelter?
   • Action: Drop a pellet
   • Sub-rule End
2. Since the sub-rule is restarted immediately after the pellet has been dropped, you must ensure the sub-rule ends when the animal has visited the reward zone. Define a condition In Feeder zone that is met when the animal has been in the Feeder zone for at least 1 s without break (Current duration >= 1s). Place this box to the left of Rule End.

Source: EthoVision XT 18 - THC - Trial and Hardware Control, Noldus Information Technology