Von Frey Up-Down Method
Overview
The von Frey up-down method, based on the Dixon staircase procedure, is the gold-standard technique for determining the 50% mechanical withdrawal threshold of the hindpaw in rodents. Calibrated monofilaments of logarithmically increasing stiffness (typically 0.008 to 6.0 g for mice, 0.4 to 26 g for rats) are applied perpendicular to the plantar surface of the hindpaw until the filament bends, delivering a defined force for approximately 3-5 seconds. The up-down algorithm begins at a mid-range filament: if the animal withdraws, the next-lower filament is applied; if no withdrawal occurs, the next-higher filament is tested. This sequential adaptive procedure converges efficiently on the 50% threshold using only 6-9 stimulus presentations per paw.
The 50% withdrawal threshold is calculated using the Chaplan formula: 50% threshold = (10^(Xf + kδ)) / 10000, where Xf is the log value of the final filament, k is a tabulated correction factor based on the response pattern, and δ is the mean log difference between filaments. A significant leftward shift in threshold (lower force evoking withdrawal) indicates mechanical allodynia, a hallmark of neuropathic and inflammatory pain states. Bilateral testing with contralateral comparison controls for systemic effects, and repeated measurements over days or weeks capture the development, peak, and resolution of pain hypersensitivity.
ConductMaze provides a structured digital workflow for the von Frey up-down procedure, guiding the experimenter through each filament application, automatically selecting the next filament based on the response, and computing the 50% threshold in real time. The software records response latency, paw withdrawal characteristics (brisk withdrawal, licking, shaking), and generates threshold-over-time plots for longitudinal pain studies. Integration with video tracking enables post-hoc verification of withdrawal responses and quantification of secondary pain behaviors.
Trial Flow
Habituation
Place animal on mesh platform in acrylic enclosure; habituate 30-60 min until exploratory activity ceases
Starting Filament
Begin with the mid-range filament in the logarithmic series (e.g., 0.4 g for mice)
Filament Application
Apply filament perpendicular to plantar surface until it bends; hold for 3-5 seconds
Response Assessment
Score positive (brisk paw withdrawal, licking, or shaking) or negative (no response)
Staircase Adjustment
Move to next-lower filament after positive response or next-higher after negative response
Threshold Convergence
Continue until 6 responses are recorded after the first direction change in the staircase
Threshold Calculation
Apply Chaplan formula to compute 50% withdrawal threshold from the response pattern
Session Complete
Record contralateral paw threshold; return animal to home cage
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Filament Range | enum | mouse-standard | Filament set: mouse-standard (0.008-6.0 g) or rat-standard (0.4-26 g) |
| Starting Filament | float | 0.4 | Starting filament force in grams (mid-range of the set) |
| Application Duration | seconds | 3 | Duration of filament contact with the plantar surface in seconds |
| Inter-Stimulus Interval | seconds | 30 | Minimum wait between successive filament applications in seconds |
| Habituation Duration | duration | 1800 | Time for acclimation on mesh platform before testing in seconds |
| Responses After Crossover | integer | 6 | Number of responses to collect after first staircase direction change |
| Paw Tested | enum | ipsilateral | Which hindpaw to test: ipsilateral, contralateral, or bilateral |
| Positive Response Criteria | enum | withdrawal | Criteria for positive response: withdrawal only, or withdrawal+licking+shaking |
Metrics
| Metric | Unit | Description |
|---|---|---|
| 50% Withdrawal Threshold | g | Mechanical force at which the animal responds 50% of the time (Chaplan method) |
| Log Threshold | log(g) | Log10-transformed threshold for parametric statistical analysis |
| Response Pattern | string | Sequence of positive (X) and negative (O) responses for pattern verification |
| Number of Applications | count | Total filament presentations required to converge on threshold |
| Contralateral Threshold | g | Withdrawal threshold of the uninjured contralateral paw as internal control |
| Threshold Change from Baseline | % | Percent change from pre-injury baseline threshold |
Sample Data
| Subject | Condition | Day | Ipsilateral (g) | Contralateral (g) | Pattern | Threshold Change (%) |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Neuropathic pain phenotyping — quantifying mechanical allodynia in nerve injury models (CCI, SNL, SNI, spared nerve injury)
- 2Analgesic drug screening — dose-response evaluation of gabapentinoids, SNRIs, and novel analgesics on mechanical hypersensitivity
- 3Inflammatory pain assessment — tracking allodynia development and resolution in CFA, carrageenan, and surgical incision models
- 4Longitudinal pain monitoring — repeated threshold measurements over weeks to characterize pain trajectory and treatment windows
Related Protocols
Compatible Products
Ready to Automate Your Behavioral Protocols?
Contact us for a demo and pricing information.
