Active Avoidance (Shuttle Box)
Overview
Two-way active avoidance (shuttle box) is a classical aversive learning paradigm in which the animal must cross from one compartment to another to avoid or escape a foot shock. A warning signal (tone or light CS) precedes the shock US by a defined interval. If the animal shuttles during the CS-US interval, the shock is avoided entirely (avoidance response); if it shuttles after shock onset, the shock is terminated (escape response).
Active avoidance requires the integration of Pavlovian fear learning (CS-US association) with instrumental learning (shuttle response), making it a valuable paradigm for studying the neural circuits underlying threat detection, action selection, and safety signal processing. The medial prefrontal cortex, amygdala, and periaqueductal gray are critically involved (Moscarello & LeDoux, 2013).
ConductMaze fully automates the shuttle box: infrared beam arrays detect compartment crossings, the software controls door guillotines, delivers scrambled shock through the grid floor, and manages CS presentation. It supports configurable CS-US intervals, inter-trial intervals, and criterion-based session termination (e.g., 10 consecutive avoidances).
Trial Flow
Trial Start
ITI elapses, CS onset (tone/light)
CS Period
CS presented for CS-US interval
Shuttle Check
Did subject cross before US onset?
Avoidance
CS terminates, no shock — avoidance response
US Onset
Shock begins if no shuttle during CS
Escape Check
Did subject cross during shock?
Escape / Failure
Record response type, latency, reset for next trial
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| CS Type | enum | Tone (2kHz) | Conditioned stimulus modality (tone, light, compound) |
| CS Duration | seconds | 10 | Maximum CS presentation time before US onset |
| US Intensity | mA | 0.3 | Scrambled foot shock intensity |
| US Max Duration | seconds | 10 | Maximum shock duration if no escape response |
| ITI Range | seconds | 20-40 | Randomized inter-trial interval range |
| Total Trials | integer | 100 | Number of trials per session |
| Criterion | integer | 10 | Consecutive avoidances to reach acquisition criterion |
| Shuttle Sensitivity | enum | 4-beam break | Number of IR beams that must be interrupted for a valid crossing |
Metrics
| Metric | Unit | Description |
|---|---|---|
| Avoidance Rate | % | Percentage of trials with successful avoidance responses |
| Escape Rate | % | Percentage of trials with escape (but not avoidance) responses |
| Failure Rate | % | Percentage of trials with no shuttle response |
| Avoidance Latency | seconds | Mean time from CS onset to shuttle on avoidance trials |
| Escape Latency | seconds | Mean time from US onset to shuttle on escape trials |
| Trials to Criterion | count | Number of trials to reach acquisition criterion |
| Inter-Trial Crossings | count | Spontaneous crossings during ITI (general activity index) |
Sample Data
| Trial | CS_Type | Response | Latency_s | Shock_Duration_s | ITI_Crossings |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Anxiety & avoidance — measuring pathological avoidance behavior relevant to anxiety disorders
- 2Antidepressant screening — learned helplessness-resistant vs susceptible phenotyping
- 3Prefrontal-amygdala circuit research — optogenetic dissection of threat-action coupling
- 4Schizophrenia models — avoidance learning deficits in NMDA receptor hypofunction models
- 5Safety signal learning — conditioned inhibition and relief learning paradigms
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