Novelty-Suppressed Feeding
Overview
The novelty-suppressed feeding (NSF) test, also known as the hyponeophagia test, measures the latency of a food-deprived animal to approach and eat a familiar food pellet placed in the center of a novel, brightly lit open arena. This conflict-based paradigm creates tension between the drive to eat (motivated by 24-hour food deprivation) and the anxiety provoked by the novel, exposed environment. The test uniquely engages both anxiety-related circuitry (basolateral amygdala, ventral hippocampus, bed nucleus of the stria terminalis) and depression-related motivational circuits (prefrontal cortex, nucleus accumbens, ventral tegmental area). This dual engagement makes NSF sensitive to chronic but not acute antidepressant treatment, mirroring the clinical therapeutic lag of 2-3 weeks observed in human patients.
The primary dependent variable is the latency to feed — defined as the time from arena placement to the first bite of the food pellet. Animals that do not eat within the maximum trial time (typically 10-12 minutes) are assigned the ceiling value and represent a censored observation requiring survival analysis (Kaplan-Meier or Cox regression). Critical control measures include home-cage food consumption immediately after the test (to verify hunger motivation), body weight loss during deprivation, and total food consumed in the arena. These controls distinguish anxiety/depression-driven suppression from general appetite changes or motor deficits.
ConductMaze automates NSF with overhead video tracking that detects arena entry, approach trajectory to the food pellet, and feeding onset through pellet displacement sensing. The software implements survival analysis statistics natively, manages the 24-hour food deprivation schedule with automated feeding-system lockout, and tracks body weight via integrated scales. Multi-day chronic dosing schedules are programmed in advance, with the software alerting experimenters to test timing based on treatment protocol requirements.
Trial Flow
Food Deprivation
Food removed from home cage 24 hours before test; water remains available.
Arena Preparation
Novel open field (typically 40x40 cm) with single food pellet secured in center; bright illumination.
Animal Placement
Animal placed in corner of arena; latency timer begins.
Approach Tracking
Video tracking records path to food, thigmotaxis, center entries, and approach-retreat sequences.
Feeding Detection
First bite detected via pellet displacement sensor or video-based jaw movement detection.
Timeout Check
If maximum latency reached without feeding, session ends with censored data point.
Home-Cage Control
Animal returned to home cage with pre-weighed food; 5-minute consumption measured as hunger control.
Session End
Data exported with feeding latency, path length, and home-cage consumption.
Parameters
| Parameter | Type | Default | Description |
|---|---|---|---|
| Food Deprivation Duration | duration | 24 h | Duration of food deprivation before test (18-24 hours standard) |
| Maximum Trial Time | duration | 10 min | Maximum time allowed for feeding; animals not feeding receive censored ceiling value |
| Arena Size | distance | 40 | Arena width and length in centimeters (square open field) |
| Illumination Level | integer | 300 | Arena illumination in lux (bright light increases anxiogenic properties) |
| Food Type | enum | Familiar Chow | Type of food placed in center (Familiar Chow, Sucrose Pellet, or Novel Food) |
| Home-Cage Test Duration | duration | 5 min | Duration of post-test home cage feeding control period |
| Placement Corner | enum | Randomized | Corner of arena where animal is placed (Randomized, Fixed, or Counterbalanced) |
| Center Zone Radius | distance | 10 | Radius of center zone around food pellet for approach metrics (cm) |
| Weight Loss Criterion | float | 15.0 | Maximum acceptable body weight loss during deprivation as percentage; animals exceeding this are excluded |
Metrics
| Metric | Unit | Description |
|---|---|---|
| Feeding Latency | seconds | Time from arena placement to first bite — primary outcome (censored at max trial time if no feeding) |
| Fed Within Cutoff | boolean | Whether the animal ate within the maximum trial time (for survival analysis censoring) |
| Home-Cage Consumption | grams | Food consumed during the post-test home-cage control period — verifies hunger drive |
| Body Weight Change | % | Percent body weight loss during the deprivation period |
| Path Length to Food | cm | Total distance traveled before first feeding approach — measures exploratory anxiety |
| Center Zone Entries | count | Number of entries into the center zone around the food pellet before feeding |
| Approach-Retreat Events | count | Number of times animal entered then exited center zone without feeding — measures conflict |
Sample Data
| Animal | Group | Latency_s | Fed | HC_Consumption_g | BW_Change_pct | Path_cm | Center_Entries | Approach_Retreats |
|---|
Representative data for illustration purposes. Actual values will vary by species, strain, and experimental conditions.
Applications
- 1Chronic antidepressant validation — NSF uniquely requires chronic dosing (14-21 days) for efficacy, modeling clinical therapeutic lag
- 2Anxiety-depression comorbidity — conflict paradigm simultaneously engages anxious and depressive circuits in a single test
- 3Neurogenesis-dependent behavior — NSF is sensitive to hippocampal neurogenesis blockade, linking adult neurogenesis to antidepressant response
- 4Rapid-acting antidepressant discovery — ketamine and psilocybin reduce NSF latency within 24 hours, bypassing the chronic treatment requirement
- 5Diet and metabolism interaction — food deprivation component allows study of metabolic-mood interactions and ghrelin signaling
Compatible Products
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