Distinguish micro-movements from true activity for immobility
Balance micro-swaying in water should count as immobility; many tools misclassify it. AI classification captures immobility more accurately and reduces manual scoring.
FSTDepression-like5 min read
Forced Swim Test
Forced Swim Test (FST): Principles & Protocol
Overview
The Forced Swim Test (FST) evaluates depression-like behavioral despair by placing rodents in an inescapable water cylinder. The transition from active struggle to passive floating—and the proportion of immobility—is a core despair readout.
FST is a cornerstone antidepressant screen used in depression mechanisms, stress models, psychiatric phenotypes, and hippocampal/prefrontal and neuroendocrine studies.
Methods
- 1Place the mouse in a 2 L beaker with 14 cm water at 23–24 °C; record video for 6 min. Change water between animals and opaque separators between beakers to limit odor and social interference.
Software capabilities
Full quantification of despair endpoints
Typical 6 min tests use 2 min adapt + 4 min scoring. Report first immobility latency, total immobility, and related indices for antidepressant research.
Custom time windows (e.g., last 4 minutes)
Analyze immobility in selected intervals—such as the last 4 minutes—without manual clipping, avoiding adaptation-period contamination.
Analysis parameters
Advanced parameters
| Parameter | Description | Meaning | Unit |
|---|---|---|---|
| immobility_total_time | Total immobility time | Immobility: animal stops struggling and remains largely still (vertical floating posture in FST) | s |
| immobility_Ns_time | Immobility in a selected window | After computing total immobility, extract immobility within N minutes (e.g., last 4 or first 5) | s |
| immobility_time_ratio | Immobility time ratio | Total immobility / total time | % |
| first_immobility_time | Latency to first immobility | Time from start until first immobility bout | s |