Freezing Duration
Time spent motionless after stimulus onset
ConductVision · Behavioral Analysis
Looming Visual Stimulus
Assess innate defensive responses to expanding overhead visual threats.
RodentInnate FearAuto Export
ConductVision / Looming Visual Stimulus
Recording / Trial 3subject tracked
Escape Latency0.38s
Freeze Duration2.1s
Escape Speed42cm/s
Key Parameters
Metrics automatically extracted by ConductVision.
Flight Latency
Time from looming onset to shelter entry
Flight Speed
Peak velocity during escape to the shelter
Shelter Time
Duration spent in the shelter zone after escape
Response Type
Classification as flight, freeze, or no response
Tail Rattling
Defensive tail-shaking episodes in response to the looming stimulus
+ 5 more parameters trackedShow allHide
Response Probability
Proportion of stimulus presentations eliciting a defensive response
Time to Return
Latency from shelter entry to re-emergence into the arena
Pre-Stimulus Activity
Baseline locomotion before stimulus onset for normalization
Stimulus-Evoked Distance
Total path length during the 10 s post-stimulus window
Habituation Rate
Response magnitude decline across repeated stimulus presentations
What is the Looming Visual Stimulus Test?
The looming visual stimulus test probes innate defensive behavior by projecting an expanding dark disc overhead, simulating an approaching aerial predator. Mice respond with flight to a shelter, freezing, or tail rattling — responses that do not require learning and are mediated by the superior colliculus and amygdala.
ConductVision synchronizes overhead stimulus delivery with high-resolution tracking, automatically classifying response type and measuring flight kinematics. The test is widely used in circuits-level fear research and optogenetics studies.
Protocol Parameters
| Parameter | Description | Default |
|---|---|---|
| Arena Size | Open arena with overhead display | 50 × 50 cm |
| Shelter Size | Enclosed refuge in one corner | 10 × 10 × 10 cm |
| Display Height | Overhead screen or projector distance from arena floor | 30–40 cm above |
| Stimulus Type | Expanding dark disc on light background | Black disc, 2° to 20° expansion |
| Expansion Duration | Time for stimulus to reach maximum angular size | 250–500 ms |
| Number of Presentations | Stimulus repetitions per session | 5–10 |
| Inter-Stimulus Interval | Time between successive looming presentations | 60–120 s |
| Habituation Period | Free exploration before first stimulus | 5–10 min |
| Response Window | Time after stimulus onset to score defensive response | 10 s |
Interpreting Results
↑
Increased Flight Response
Enhanced threat sensitivity — faster, more frequent flight to shelter seen after amygdala kindling or chronic stress.
↓
Reduced Flight Speed
Impaired escape kinematics — slower shelter-directed movement after motor cortex or superior colliculus lesions.
↑
Prolonged Shelter Time
Sustained fear state — extended hiding after looming indicates elevated defensive state, sensitive to anxiolytic treatment.
↓
Decreased Response Probability
Impaired threat detection — failure to respond to overhead looming seen after superior colliculus lesions or visual pathway damage.
↑
Increased Freezing over Flight
Shift in defensive strategy — freezing dominates when shelter is removed or at greater distance, mediated by PAG circuits.
↓
Rapid Habituation
Reduced threat salience — fast response decline across repeated presentations suggests impaired sustained threat vigilance.
Research Applications
Innate Fear Circuits
- Superior colliculus — retino-collicular threat detection pathway dissection
- PAG circuits — dorsal PAG flight vs ventral PAG freezing command centers
- Amygdala — CeA and BLA contributions to innate vs learned defensive responses
Optogenetics & Imaging
- Circuit activation — ChR2 stimulation of SC-PBGN-amygdala flight pathway
- Calcium imaging — GCaMP recording of threat-responsive neurons during looming
- Fiber photometry — real-time neural dynamics during flight decision-making
Defensive Behavior
- Threat assessment — distance-dependent flight vs freeze decision modeling
- Anxiolytic evaluation — diazepam and propranolol effects on innate threat reactivity
- Predator-prey dynamics — evolutionary conserved aerial threat response across species
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