Marble Burying Test

The marble burying test measures repetitive, compulsive-like digging behavior by presenting rodents with a standardized grid of 20 glass marbles (typically arranged 5 x 4, evenly spaced) placed on 5 cm of clean bedding material in a standard polycarbonate cage. During a 30-minute session, mice or rats will spontaneously displace bedding over the marbles through natural digging behavior. The number of marbles buried (defined as more than two-thirds covered by bedding) at session end serves as the primary endpoint. This behavior is driven by circuits involving the cortico-striatal-thalamic loop, with dorsal striatum and orbitofrontal cortex activity correlating with burying intensity.

The marble burying response is pharmacologically dissociable from general locomotor activity and anxiety per se: SSRIs (fluoxetine, fluvoxamine), 5-HT2C antagonists, and benzodiazepines all reduce marble burying without proportionally reducing locomotor activity when dosed appropriately. This pharmacological profile aligns more closely with obsessive-compulsive disorder (OCD) than with generalized anxiety, making the test particularly valuable for screening compounds targeting repetitive or perseverative behaviors. The number of marbles buried, spatial pattern of burying (clustered vs. distributed), and the latency to first burying bout provide complementary measures.

ConductMaze captures a high-resolution overhead image at session start (with the intact marble grid) and at session end, then uses computer vision to automatically count buried marbles by detecting marble visibility against the bedding. The system also supports optional continuous video tracking to quantify digging bouts, digging duration, locomotor activity, and the time course of marble displacement throughout the session, eliminating the need for manual marble counting.