Vogel Conflict Test
Overview
The Vogel conflict test (Vogel et al., 1971) is a punishment-based anxiety paradigm in which water-deprived rodents receive a mild foot shock or lip shock after a set number of licks from a water spout. The conflict between the drive to drink and the aversive consequence of shock produces a suppression of licking that is selectively attenuated by anxiolytic drugs. The test is considered one of the most pharmacologically predictive models of clinical anxiolytic efficacy, with strong sensitivity to benzodiazepines, barbiturates, and serotonergic anxiolytics (Millan & Brocco, 2003).
Primary dependent variables include the number of punished licks (licks completed despite shock delivery), number of shock-free licks in unpunished periods, total number of shocks accepted, and the punishment ratio (punished licks / total licks). Secondary measures include latency to first lick, inter-lick interval patterns, and lick bout structure. Anxiolytic compounds increase the number of punished licks without affecting unpunished licking, distinguishing anti-conflict effects from general motor stimulation.
ConductMaze controls the lickometer circuit, shock delivery through the spout or grid floor, and the punishment schedule (fixed-ratio or variable-ratio). The software counts licks in real time, delivers shock after the programmed number of licks, and computes conflict metrics across configurable punishment schedules. Unpunished pre-test periods establish baseline lick rates for normalization.
Trial Flow
Water Deprivation
Animals water-deprived for 24–48 h prior to testing to establish drinking motivation.
Unpunished Baseline
3 min access to water spout without shock; baseline lick rate and latency measured.
Punishment Phase Onset
Shock contingency activated; shock delivered after every N licks (e.g., FR-20 schedule).
Lick-Shock Monitoring
System counts licks and delivers shock when ratio criterion met; records punished vs. unpunished licks.
Conflict Period
Animal continues 3 min punished period; total shocks accepted and lick patterns recorded.
Metric Computation
Punished licks, shocks accepted, punishment ratio, and lick bout structure calculated.
Session End
Data exported; animal returned to home cage with ad libitum water for 1 h recovery.
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Deprivation Period | integer | 48 | Water deprivation duration in hours prior to testing. |
| Shock Intensity | float | 0.3 | Shock intensity in milliamps (mA); adjusted per species (0.1–0.5 mA). |
| Shock Duration | float | 1.0 | Duration of each shock pulse in seconds. |
| Punishment Ratio | integer | 20 | Fixed-ratio schedule: number of licks between successive shocks. |
| Unpunished Period | integer | 180 | Duration of shock-free baseline period in seconds. |
| Punished Period | integer | 180 | Duration of punishment phase in seconds. |
| Spout Lickometer Sensitivity | integer | 5 | Minimum tongue contact duration (ms) to register as a lick. |
Metrics
| Metric | Unit | Description |
|---|---|---|
| Unpunished Licks | count | Total licks during the shock-free baseline period. |
| Punished Licks | count | Total licks during the punishment phase; primary anxiolytic endpoint. |
| Shocks Accepted | count | Number of shock deliveries tolerated during the punishment phase. |
| Punishment Ratio | ratio | Punished licks / (unpunished + punished licks); higher values indicate anxiolytic effect. |
| Latency to First Lick | s | Time from spout access to first lick, reflecting approach motivation. |
| Mean Inter-Lick Interval | ms | Average time between consecutive licks; reflects microstructure of drinking. |
| Lick Bout Count | count | Number of discrete licking bouts (separated by ≥ 2 s pause) during punishment phase. |
Sample Data
| Subject | Group | Unpunished Licks | Punished Licks | Shocks Accepted | Punishment Ratio |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Anxiolytic drug screening — benzodiazepines, barbiturates, and 5-HT1A agonists dose-dependently increase punished licking.
- 2GABA-A receptor pharmacology — subtype-selective modulators (alpha-2/3 selective) tested for anti-conflict efficacy without sedation.
- 3Anxiety disorder modeling — validating transgenic or stress-induced anxiety phenotypes with pharmacological reversal.
- 4Novel anxiolytic targets — screening CRF1 antagonists, neurosteroids, and endocannabinoid modulators.
- 5Pain-anxiety interaction — evaluating how chronic pain states alter conflict behavior and anxiolytic responsiveness.
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