Knowledge Base

Problem

Users want to analyze the Tail Suspension Test (TST) in EthoVision XT and are unsure which analysis approach or parameters to use to quantify immobility (i.e., struggling vs. not struggling).

Details

The Tail Suspension Test requires distinguishing periods of active struggling from periods of immobility (despair). EthoVision XT can analyze this using its Activity Analysis (pixel-change based mobility classification), which is well suited to detecting movement versus stillness in suspended animals. This is analogous to the approach used for forced swim test and other immobility-based assays. Relevant for behavioral neuroscience users running depression or despair models.

Solution

1. Set up your TST video(s) in EthoVision XT as standard trials.
2. For arena setup, define the arena to encompass the animal's full range of motion during suspension.
3. In the Analysis Profile, use the 'Activity State' parameter (Activity Analysis), which quantifies pixel change between frames to determine whether the animal is moving or immobile.
4. Adjust the Activity threshold to suit your camera setup and animal size — manually review a sample of video to confirm the threshold correctly distinguishes struggling from immobility.
5. Set an appropriate minimum immobility duration to avoid counting very brief pauses as true immobility bouts.
6. Run analysis and export results (total immobility time, number of immobility bouts, latency to first immobility) to Excel for statistical analysis.
7. Note: Because the animal is suspended and not locomoting, center-point tracking is less relevant; focus on activity/immobility measures rather than distance moved or zone-based parameters.