Knowledge Base

The Start-Stop Trial Rule (Continued)

1. Create a Reference to the sub-rule (see page 63) and specify to have the sub-rule repeated 25 times. Place the resulting box at the left side of the Stop track box.

Eight-Arm Radial Maze

Stop the trial when the subject has been in four arms within 10 minutes. Combine eight conditions, one for each arm. At least four conditions must be met, no matter which arm the animal visits.

1. Create an In zone condition (see page 92) and specify that the Frequency for Arm 1 must be >=1. That is, the animal must have visited Arm 1 at least once. Do the same for each of the other arms.
2. Connect the resulting eight condition boxes in parallel using the N of All operator (see Figure 17).
3. Set the Maximum trial duration (see page 21) to 10 minutes to stop tracking in the case the animal fails to visit four arms in the meantime.

For more information on operators of type N of All, see page 40.

Important: The frequency of In zone can become high very easily when the animal walks along the edge of a zone. This may result in the condition being met sooner than expected. If that happens, increase the Zone exit threshold. If that does not help, open the Detection settings and click Advanced, then under Smoothing set Track noise reduction to On. This smooths the track.

Figure 17

A Trial Control sequence for an eight-arm radial maze. The trial must stop when the animal has visited four of the arms at least once.

• 1, 2,...8 - In zone condition boxes for Arm 1, 2,... respectively. A condition is met when the Frequency of In zone for that arm is greater than or equal to 1.
• A - Operator that checks that at least four of the eight conditions are met.
• B - Stop track box. When four conditions are met, the trial is stopped.

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