Knowledge Base

Nesting over Time

Aim

To pick out the samples in one time interval, from time t_start to time t_end.

Procedure

1. In the Data Profile, under Nesting, click the button next to Time. Note that choosing Time under Nesting over Subjects leads to the same data selection.
2. In the Time window, enter the Interval start and Interval end:
   • Relative time is the time since the start of the track. Enter the relative time. In EthoVision XT 17.5 and later, you can specify any time within the trial, even after 24 hours.
   • Track start / Track end mark the start and end of each track, respectively. Therefore, they may mean different relative times between tracks.
3. Complete the procedure from step 4 in How to Select Track Segments.

Examples

• To analyze the first 10 minutes of each track, set Interval start to 0:00:00.000 and Interval end to 0:10:00.000.
• To analyze from 10 minutes to the end of each track, set Interval start to 0:10:00.000 and Interval end to Track end.

Notes

• Time intervals are applied in each track independently.
• Default: Interval start 0:00:00.000 (h:mm:ss.fff), Interval end 0:00:30.000.
• 0:00:00.000 represents the time that tracking started for that arena. With multiple arenas, tracks may actually start at different times within the same trial.
• If you want to split the data in regular intervals (for example, a one-hour recording in six 10-minute intervals), do not nest over time. Instead, in the Data profile choose Results per Time Bin.
• Tip: If you want to select a track segment that lasts some time relative to an event (for example, select the 10 seconds after the presentation of a stimulus, or select up to when an object is explored for 1 minute), then choose Free Interval instead. See Nesting over a Free Interval.
• When working with multiple arenas, if you apply Trial Control with Start and Stop conditions for each arena separately, actual data recording may start and stop at different times in each arena. For example, if tracking started automatically as soon as the animal was detected, and the mouse in Arena 1 was released earlier than in Arena 2, tracking started earlier in Arena 1. When nesting over time and selecting the first minute of each track, the two track segments may not overlap completely on the timeline.
• When working with multiple subjects per arena, tracking starts at the same time for all subjects within an arena. Therefore, nesting over time results in the same interval being selected for all subjects. Note that tracking starts for all subjects even when one has not been released yet, in which case the track for that subject begins with missing samples.

Nesting Using Zones

Nesting over In Zone

Aim

To pick out the data collected when one or more subjects were in a specific zone, or in a combination of zones. Nesting over In Zone is only necessary when you want to analyze track segments by combining zones or subjects. If you simply want to calculate statistics of distance, velocity, etc. for each zone without combining subjects or zones, see Calculate the Results per Zone.

Nesting vs. Nesting over Subjects

Notice the difference when there are multiple subjects in the same arena:

• To select data of a subject based on that subject being in specific zones, choose In Zone under Nesting. See also item B in Nesting vs. Nesting over Subjects.
• To select data of a subject based on other subjects being in specific zones, choose In Zone under Nesting over Subjects. There you find the Actors tab where you can specify which subjects (Actors) were in the selected zone(s). See items C and D in Nesting vs. Nesting over Subjects, and the procedure in Nesting over Subjects.

Procedure

1. In the Data Profile, under Nesting, click the button next to In Zone.
2. In the In Zone window, under In the Following Zones, deselect Arena and select the zones in which the animal must be.
3. Choose the remaining options to specify which combination of zones (any, all, not in any) and body points. For explanation, see Dependent Variables in Detail > In Zone.
4. Click OK. Proceed with step 4 in How to Select Track Segments.

Notes

• If your experiment is set to Only Center-Point Detection, the From Following Body Points options are not available. Calculations are based on the center-point of the body.
• Select When in All Selected Zones only when the zones are overlapping at least partially (for example, North Quadrant and Center of an open field).

Nesting Over Zones

When two zones are not overlapping, selecting "When in all selected zones" results in no data being selected, because a body point can never be in two different locations at the same time.

Application Examples

Example 1: A Center zone has been defined in an open field. When you do Nesting and choose Center under "In the following zones," the samples in the center of the open field are selected for analysis. When you visualize the track, selected samples are displayed in bright colors; non-selected samples are dimmed out.

Example 2: For the same open field as above, but when also tracking the nose and tail-base points, if you select the three body points and select "All selected points" from the list, a sample is only selected when the three body points are within the Center zone. In the example below, the tail-base is outside the Center zone (highlighted in yellow). Therefore, that sample is not selected for analysis.