Conditioned Place Preference
Overview
Conditioned place preference (CPP) is a classical conditioning paradigm that measures the rewarding or aversive properties of pharmacological or natural stimuli by pairing them with distinct environmental contexts. The apparatus consists of two or three compartments differentiated by visual, tactile, and sometimes olfactory cues. During conditioning, the subject receives the unconditioned stimulus (drug injection) in one compartment and vehicle in the other across alternating sessions. The mesolimbic dopamine system, particularly ventral tegmental area projections to the nucleus accumbens, mediates the formation of drug-context associations underlying CPP.
The primary outcome measure is the CPP score, calculated as post-conditioning time in the drug-paired compartment minus pre-conditioning time in the same compartment. A positive shift indicates the stimulus has rewarding properties, while a negative shift indicates aversion. Absolute time in each compartment, number of compartment transitions, and latency to enter each side provide supplementary measures. The pre-test bias score determines whether an unbiased or biased assignment protocol is appropriate for the cohort.
ConductMaze automates CPP with infrared beam-break or video-based position tracking across compartments, providing real-time dwell-time calculations with sub-second resolution. The software manages the full pre-test, conditioning, and post-test schedule, including automated door control for compartment access. Preference scores, shift indices, and transition counts are computed for each phase and exported alongside raw position timelines. The platform supports biased and unbiased protocols with automatic compartment assignment algorithms.
Trial Flow
Habituation
Subject freely explores all compartments with doors open for baseline familiarization.
Pre-Test
Record baseline time in each compartment with free access to determine initial preference.
Conditioning Sessions
Alternate drug-paired and vehicle-paired confinement sessions across conditioning days.
Post-Test
Record time in each compartment with free access to assess conditioned preference.
Preference Calculation
Compute CPP score as post minus pre time in drug-paired compartment; evaluate statistical significance.
Data Export
Export preference scores, transition counts, and dwell time for all phases.
Protocol Complete
Clean apparatus with unscented detergent; ensure no olfactory carryover between subjects.
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Pre-Test Duration | duration | 20 min | Duration of baseline free-access session to establish initial compartment preference. |
| Conditioning Session Duration | duration | 30 min | Duration of each drug-paired or vehicle-paired confinement session. |
| Number of Conditioning Pairs | integer | 4 | Number of drug-vehicle session pairs across the conditioning schedule. |
| Post-Test Duration | duration | 20 min | Duration of the post-conditioning free-access preference test. |
| Assignment Protocol | enum | unbiased | Compartment assignment method: unbiased (counterbalanced) or biased (drug in non-preferred). |
| Door Open Delay | seconds | 5 | Delay after subject placement before guillotine doors open in free-access sessions. |
| Bias Threshold | seconds | 120 | Maximum pre-test side difference allowed for unbiased protocol inclusion. |
| Conditioning Interval | duration | 24 hr | Minimum time between consecutive conditioning sessions. |
Metrics
| Metric | Unit | Description |
|---|---|---|
| CPP Score | s | Post-test minus pre-test time in the drug-paired compartment. |
| Pre-Test Drug Side Time | s | Baseline time spent in the compartment later paired with drug. |
| Post-Test Drug Side Time | s | Time in the drug-paired compartment during the post-conditioning test. |
| Compartment Transitions | count | Number of crossings between compartments during free-access sessions. |
| Latency to Drug Side | s | Time from door opening to first entry into the drug-paired compartment. |
| Center Time | s | Time in the neutral center compartment during free-access sessions. |
| Distance Traveled | cm | Total locomotor activity during the post-test session. |
Sample Data
| Subject | Group | Pre Drug Side (s) | Post Drug Side (s) | CPP Score (s) | Transitions |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Abuse Liability Assessment — Screen novel compounds for rewarding properties by measuring CPP magnitude across dose-response curves.
- 2Dopaminergic Circuit Dissection — Combine CPP with optogenetic or chemogenetic manipulation of VTA-NAc projections to map reward encoding circuits.
- 3Natural Reward Valuation — Measure the rewarding properties of social interaction, palatable food, or exercise as unconditioned stimuli.
- 4Addiction Pharmacotherapy — Evaluate whether candidate anti-addiction medications attenuate drug-induced CPP at therapeutic doses.
- 5Sex Differences in Reward — Compare CPP acquisition rates and magnitudes between male and female rodents to characterize sex-dependent reward sensitivity.
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