Knowledge Base

Definition

A discrete (point event) variable that is scored when the focal subject joins or leaves a group of conspecifics. Because it is a point event variable, it has no duration.

• Make group of size n (2 to 4). The subject joins a group of n-1 subjects to form a group of n subjects in contact with each other.
• Break group of size n (2 to 4). The subject leaves a group of n subjects. The group is now of size n-1, or does not exist anymore in the case of n=2.

Calculation

EthoVision XT detects the make/break events based on the state of type Group.

• If the subject is not in contact with any subject one video frame before the start of the event Group, a Make group event is scored.
• If the subject is not in contact with any subject one video frame after the end of the event Group, a Break group event is scored.

NOTE: In EthoVision XT, a point event is an event with no duration. In contrast, state events have a duration.

How to Specify Make and Break Group

1. Open an Analysis profile and in the Dependent Variables panel, under Live Mouse Tracker, click the Add button next to Make and break group.
2. Specify the Group size. This is the final size when making a group, or the initial size when leaving a group. For example, enter 3 if you want to have the instances when a subject joined another subject to form a group of three subjects, or left a group of three, so the group became two subjects.
3. Complete the procedure to add the variable to the Analysis profile. See Calculate Statistics: Procedure.

Applications

In a study of a mouse model of ASD, Shank2 mutant mice observed in a social context displayed increased frequency of completing or breaking a group of three or four mice (de Chaumont et al. 2019. Nat. Biomed. Eng. 3: 930-942).

Note

While Group is a state event that aims at quantifying the time that a subject was part of a group, Make and break group is a point event variable; that is, it tells you exactly when the subject joined or left a group.

See Also

• Dependent variables for Live Mouse Tracker

Make Contact

Definition

A discrete (state event) variable that is scored when the subject approaches another one to make contact with it.

Calculation

Make contact is scored when the following conditions are met simultaneously:

• The distance between the focal subject and the other subject shortens (approach event).
• The speed of the focal subject is higher than that of the approached subject. If the speeds of the two animals involved in the contact are not different enough, Make contact is not computed.
• The contact event starts some time during the approach event or immediately after the end of the approach event. That is, the video frame immediately before a contact event must be within the timeline of the approach event.
• The contact event lasts more than three video frames. Instances of contact separated by one video frame are merged together.

An instance of Make contact starts at the start time of approach and ends at the video frame just before the contact event. It does not include the time of contact.

NOTE: In Live Mouse Tracker, contact between subjects is detected when the distance between the contours gets below a fixed threshold. Contact is detected during data acquisition and its settings cannot be modified in EthoVision XT.

How to Specify Make Contact

1. Open an Analysis profile.
2. In the Dependent Variables panel, under Live Mouse Tracker, click the Add button next to Make contact.
3. Complete the procedure to add the variable to the Analysis profile. See Calculate Statistics: Procedure.

Example

Subject B has made contact with subject C.

See Also

• Dependent variables for Live Mouse Tracker

Move

Definition

A discrete (state event) variable that marks the time that the focal subject makes some displacement in space. The subject may move alone or in contact with any other subject.

Calculation

EthoVision XT considers the subject moving for the time between two subsequent events of type Stop. Events of type Stop are scored when the speed of the subject is lower than the threshold value (5.26 cm/s or 2 5/64 in). This threshold is set in the Live Mouse Tracker algorithms and cannot be changed.

How to Specify Move

1. Open an Analysis profile and in the Dependent Variables panel, under Live Mouse Tracker, click the Add button next to Move.
2. Under Calculate Statistics for, select Move in contact, Move alone, or both.
3. Click the Receivers tab. These apply when you select Move in contact. Under Select, choose the subjects that were in contact with the focal subject while it was moving. If you select two or more subjects, select one of the available options from the list:
   • All selected subjects: Move in contact is scored only when the focal subject was in contact with all the subjects selected above.
   • Any selected subject: Move in contact is scored when the focal subject was in contact with any of the subjects selected above.
   • Each subject: Move in contact is scored when the focal subject was in contact with one of the subjects selected above. The results are displayed for each Receiver.
4. Complete the procedure to add the variable to the Analysis profile. See Calculate Statistics: Procedure.

Example

In the Trial Statistics results table, with the default layout, the results of Move are shown per subject (on the rows). The columns vary depending on what you chose in the Receivers tab.

• If you chose Each subject, the columns contain the statistics of Move in contact with specific subjects (With A to D).
• If you chose All selected subjects or Any selected subject, a column With all of A, B, C, D or With any of A, B, C, D contains cumulative statistics of Move when the subject was in contact with all cage mates or any of them, respectively, depending on which option you chose.

Notes

• Move may look similar to EthoVision XT's Movement, with its possible states Moving and Not moving. However, the results may not always overlap. Movement uses two adjustable speed thresholds, which filter the changes in velocity in a different way.

See Also

• Dependent variables for Live Mouse Tracker

Source: EthoVision XT 19 Help, Noldus Information Technology