# Analyzing track segments

In EthoVision XT you can pick out segments of tracks specified by time intervals or the behavior of the subject. To do so, use the Nesting function in the Data profile.

When Nesting is activated, analysis is carried out on the samples within those track segments, and the corresponding video and external (physiological) data. The track segments outside the selection are not included in the analysis.

Below: A track represented by samples on a time line. The sketch shows a mouse entering a zone someway in the middle of the track, then sniffing air towards the end. The time lines at the bottom represent the samples selected for analysis when nesting over a zone, over time (for example, the first half of the track), or over a behavior (in this example, sniffing), respectively.

An important difference

Selecting a variable in the Data profile is not the same as selecting the same variable in the Analysis profile. For example:

▪When you choose In zone under Nesting in the Data profile, you select the samples when the animal was in a zone. Then, in the Analysis profile you choose a dependent variable, like Velocity. As a result, EthoVision XT calculates the velocity of the subject when it was in the zone.

▪When you choose In zone under Location in the Analysis profile, EthoVision XT calculates statistics for the variable In zone, for example, the time spent in a zone, or the number of zone entries, but not the velocity of the subject when it was in that zone.

Nesting options

▪Nesting over time, to analyze a time interval defined by a Start time and a Stop time.

example Analyze the first 15 minutes or each track.

▪Nesting over zones, to analyze the track segments when one or more subjects are within a zone or a combination of zones.

example Analyze the behavior of the mouse when its nose point was in a zone defined around the novel object.

▪Nesting over behavioral states, to analyze the track segments corresponding to the state of one or more subjects (for example, Movement, or Grooming).This option includes manually-scored behaviors and behaviors recognized automatically.

example 1 Analyze all the samples collected when the animal's body was stretched (this can be done with the Body elongation dependent variable).

example 2 Analyze the locations where the animal was sniffing.

▪Nesting over trial control states, to analyze the track segments corresponding to the time between two events of Trial Control.

example Analyze the time from when the cue light switched on to when the mouse consumed the food item delivered.

▪Nesting over subjects, to analyze the track segments based on the behavior of another subject. This is available when your arena contains multiple subjects, like in a social interaction test.

example The researcher wants to analyze the track segments of Subject 1 when Subject 2 was In proximity of Subject 1.

Notes

▪Track segments defined with Nesting are left-closed [A, B). That is, the start sample A, not the stop sample B, is included in the analysis.

▪To analyze entire tracks, use the Filter function. See Filter tracks.

▪You can also combine Filter and Nest boxes to create complex selections. See Complex Data Selections