Knowledge Base

Certain Time

Aim

In this example we want to filter the behavioral states (e.g. Not Moving). We want to remove the instances of Not Moving that last less than 1 second.

Solution

1. In the Analysis profile create a free interval with Movement as a criterion.
   • Start Criterion: Select Dependent variable.
   • Start at: Enter the minimum time duration. In this example, 1 s.
   • Select variable: Choose the behavior. In this example, Movement.
   • Statistic: Current Duration.
   • Settings: Define the behavior state. In this example, Not Moving is chosen, based on thresholds Start velocity 2.0 cm/s and Stop velocity 1.5 cm/s.
   • Stop criterion: The main difference from the Start criterion is that you must select the opposite of the behavior above. In this example, under Settings, Moving is selected with the same thresholds as above, and the Statistic is Current; then select true. Next to Stop at, leave 0.0 selected.
2. In the Integrated Visualization you can check if the free interval works as expected.
   • The first plot shows the typical Movement variable, with the two states Moving and Not Moving.
   • The second plot is that of the free interval defined above. It plots the instances of Not Moving longer than 1 s, while ignoring the shorter instances.
3. Calculate the statistics of the free interval.

TIP In the interval definition, select Calculate results for interval 1 to ... if you want results for each instance of the filtered behavior. On the Trial Statistics tab, choose the statistic that you need:

• Choose Frequency to know how many instances of the filtered behavior occur.
• Choose Latency to first to know at what time that behavior occurs, for each instance.

See Also

• Free interval based on a dependent variable
• Free interval based on a Trial Control event
• Free interval based on hardware
• Free interval based on multiple subjects
• Analysis advisor

Procedure

When working with multiple subjects per arena, you can define free intervals in two ways:

• Under Nesting, choose Free interval to define a free interval for each subject separately. The interval is based on the behavior of that subject, not the other(s). As a result, for each subject a specific time period is selected.
• Under Nesting over Subjects, choose Free interval to define an interval based on a combination of conditions based on two or more subjects. The resulting interval is applied to all subjects. As a result, the same time period is selected for all subjects.

Example

Your arena contains two subjects. A free interval is defined that goes from Total Distance moved >= 100 to Total Distance moved >= 200.

• If you choose Free interval from Nesting, the start/stop criteria are applied per subject, resulting in most cases in different time periods being analyzed for each subject. Below: Time plot of a dependent variable (in this example, Distance moved) after defining the Free interval from Nesting. Different time periods are analyzed for Subject 1 (from A1 to B1) and Subject 2 (from A2 to B2).
• If you choose Free Interval from Nesting over Subjects, the start/stop criteria are applied per subject, but the intervals are defined after combining the criteria based on what is selected in the Actors tab. Below: Time plots of a dependent variable (in this example Distance moved) after defining a Free interval from Nesting over Subjects (compare with the previous figure). Depending on what is selected in the Actors tab:
  • With All selected subjects (top): The time period shared between subjects (from A1 to B2).
  • With Any selected subject (middle): The time period defined by at least one subject (from A2 to B1).
  • With one subject selected (bottom): The time period defined by the criterion met by that subject (in this example, subject 2; therefore, from A2 to B2).

Definition

A segment of track that corresponds to the combination of the value of one, two or more dependent variables.

Use Cases

• In Trial Control: Stop the trial when exploration time reaches a specified value. In a Novel object test, stop the trial when the exploration of an object reaches 30 seconds. Exploration is defined as (a) Nose point in the zone "object sniffing zone", and (b) Head direction pointing to the "object sniffing zone". When the total time that (a) and (b) are simultaneously true reaches 30 s, stop the trial. TIP Define this condition in the Trial Control Settings.
• In Analysis: Calculate the time that the animal swims pointing to the platform. In a probe trial of the Morris water maze test, the subject swims for a number of seconds around the platform. You want to know how long the animal points to the platform while it is swimming. This can be translated to (a) Heading to platform less than a user-defined angle (for example 10 degrees) and (b) Velocity higher than a user-defined value (for example 10 cm/s). TIP Define this in the Analysis profile.

Calculation

The track segments are defined for each condition independently. Then, the track segments are combined according to the logic specified (All conditions true = AND; Any condition true = OR).

Below: The variable Multi condition marks the time when the animal swims towards the platform with a certain speed. Here the multi condition is defined with three conditions: (1) Heading to platform less or equal than +15 degrees; (2) Heading to platform greater than -15 degrees; (3) Velocity greater than 10 cm/s. Conditions are combined with All conditions true. The first plot shows Multi condition; the second Heading to point (center of the platform), with both negative and positive values; the third plot Velocity.

To Specify a Multi-Condition

1. In the Analysis profile, under Custom Variables, click the button next to Multi condition.
2. Click the Add button at the right of Add conditions.
3. Choose the variable from the Select variable list.
4. To specify further options, click Settings. Next, specify which values (or range of) make the condition true.
5. Click OK. The condition is added to the list.
6. Repeat steps 2–5 to add more conditions.
7. Combine the conditions with All conditions are true (AND logic) or Any condition is true (OR logic).
8. Complete the procedure to add the variable. See Calculate statistics: procedure.

Notes

• To define a Multi condition you can use continuous variables, like Distance moved, and state variables, like In zone (excluding Activity state and Acceleration state).
• Variables that are not available include: variables representing points in time, like Rotation, Zone transition, Zone alternation; behaviors of Behavior Recognition; and behaviors scored as point events.
• To edit a condition, select that condition in the list and click Edit. To delete a condition, click that condition and click Delete.

See Also

• For how to use a Multi condition in Trial Control, see the EthoVision XT 19 - Trial and Hardware Control - Reference Manual.
• To analyze the track segments based on the Multi condition, see Nesting over a Multi condition in the Data profile.

Source: EthoVision XT 19 Help, Noldus Information Technology