Von Frey Filament Test
Overview
The von Frey filament test is the gold-standard method for measuring mechanical sensitivity (allodynia and hyperalgesia) in rodent models of pain. Animals are placed on a mesh floor inside an enclosure, and calibrated monofilaments of increasing force are applied to the plantar surface of the hind paw. Each filament bends at a defined force, providing precise and reproducible mechanical stimulation.
The up-down method (Dixon/Chaplan) is the most widely used protocol: testing begins with a mid-range filament, and subsequent filament selection depends on whether the previous application elicited a withdrawal response. This adaptive staircase procedure efficiently estimates the 50% withdrawal threshold — the force at which the animal responds to half of applications — with fewer total stimulations than ascending methods.
ConductMaze provides a digital interface for recording von Frey responses in real time. The software implements the up-down algorithm, automatically calculates 50% thresholds using the Dixon formula, tracks response patterns across filaments, and generates threshold time courses for longitudinal studies of neuropathic pain, inflammatory pain, and analgesic efficacy.
Trial Flow
Acclimate
Place animal on mesh floor, allow 30–60 min habituation
Start Filament
Begin with mid-range filament (e.g., 0.4 g for mice)
Apply Filament
Press filament perpendicular to plantar surface until it bends, hold 3–5 s
Score Response
Withdrawal/lick/shake = positive; no response = negative
Select Next
Up-down: positive → next lower filament; negative → next higher
Calculate Threshold
After 4 responses past first crossover, compute 50% threshold (Dixon)
End
Record threshold; test contralateral paw if needed
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Filament set | enum | mouse-standard | Filament range: mouse-standard (0.008–6 g) or rat-standard (0.4–60 g) |
| Starting filament | grams | 0.4 | Initial filament force for up-down method |
| Application duration | seconds | 3 | Time filament is held against paw |
| Inter-stimulus interval | seconds | 30 | Minimum time between consecutive applications |
| Habituation time | minutes | 30 | Time on mesh before testing begins |
| Method | enum | up-down | Threshold algorithm: up-down (Dixon) or ascending |
Metrics
| Metric | Unit | Description |
|---|---|---|
| 50% withdrawal threshold | grams | Force at which animal responds 50% of time (Dixon method) |
| Response pattern | string | Sequence of positive/negative responses (e.g., XOXXOO) |
| Withdrawal frequency | % | Percent withdrawal at each filament force (frequency method) |
| Threshold change | grams | Difference from pre-injury or contralateral baseline |
| Allodynia score | score | Categorical score based on threshold relative to normal range |
Sample Data
| Subject | Group | Timepoint | Left Paw (g) | Right Paw (g) | Pattern |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Neuropathic pain — gold standard for mechanical allodynia in nerve injury models (SNI, CCI, SNL)
- 2Inflammatory pain — tracks hyperalgesia time course in CFA, carrageenan, and formalin models
- 3Analgesic efficacy — dose-response curves for gabapentinoids, NSAIDs, opioids, and novel targets
- 4Diabetic neuropathy — monitors mechanical sensitivity in STZ and diet-induced diabetes models
- 5Chemotherapy-induced neuropathy — paclitaxel, vincristine, oxaliplatin peripheral neuropathy models
Related Protocols
Compatible Products
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