Defensive Burying (Shock Probe)

The defensive burying test, also called the shock-probe burying test, measures an active coping response to a localized threat. An electrified probe is mounted through the wall of a standard cage filled with bedding material. Upon contacting the probe, the animal receives a single brief shock (typically 1-2 mA, 0.5 s), after which the probe is de-energized and the animal is observed for 15 minutes. Rats and mice respond to the aversive experience by pushing bedding toward and over the probe using rapid forward movements of the forepaws, a species-typical defensive behavior mediated by circuits involving the periaqueductal gray, medial hypothalamus, and medial prefrontal cortex.

The test distinguishes two coping strategies: active coping (burying) and passive coping (immobility/freezing away from the probe). The ratio of burying time to immobility time indexes the animal's coping style and is sensitive to both anxiolytic and anxiogenic manipulations. Key dependent variables include cumulative burying duration, burying height (maximum bedding height over the probe), latency to initiate burying, number of burying bouts, immobility duration, and probe-avoidance distance (mean distance from the probe throughout the session). Benzodiazepines selectively reduce burying without increasing immobility, while anxiogenic agents increase immobility at the expense of active burying.

ConductMaze monitors animal position relative to the probe using overhead tracking, detects burying bouts through video-based motion analysis of forepaw movements in the probe vicinity, and logs probe contacts via the electrified circuit. The system automatically scores burying duration, immobility epochs, approach-avoidance patterns relative to the probe, and generates a spatial heat map showing the animal's post-shock distribution. Optional integration with a bedding-height sensor allows automated measurement of burying height at the probe location.