Cold Plate Test

The cold plate test assesses cold sensitivity by placing rodents on a temperature-controlled metal surface maintained at a noxious cold temperature, typically 0-4°C. The animal is confined within a transparent acrylic cylinder on the cold surface, and the experimenter records the latency to the first nocifensive response—paw lifting, paw licking, stamping, or jumping—as the primary endpoint. Cold nociception is mediated primarily by TRPM8 (menthol receptor) and TRPA1 channels on Aδ and C-fiber afferents, with distinct transduction profiles: TRPM8 responds to innocuous cooling (below 26°C) and becomes nociceptive near 10°C, while TRPA1 mediates responses to noxious cold below approximately 17°C. The cold plate provides a static stimulus that engages both threshold and suprathreshold cold sensing.

Cold allodynia—pain evoked by mildly cold stimuli that are normally non-noxious—is a prominent feature of neuropathic pain conditions including chemotherapy-induced peripheral neuropathy (CIPN), diabetic neuropathy, and post-traumatic nerve injury. In the cold plate paradigm, neuropathic animals exhibit dramatically shortened response latencies compared to sham or naive controls, and the magnitude of this shift correlates with the degree of cold fiber dysfunction. Extended observation protocols that count the total number of nocifensive responses within a fixed duration (typically 2-5 minutes) provide additional sensitivity, as neuropathic animals show both shorter latency and increased response frequency compared to threshold measures alone.

ConductMaze interfaces with a Peltier-controlled cold plate apparatus to maintain precise surface temperatures with ±0.3°C stability, while ventral video tracking through the transparent floor captures paw withdrawal events with frame-level accuracy. The software automatically detects paw lifts, licking bouts, and escape attempts using pose-estimation algorithms, eliminating subjective scoring bias. Temperature ramp protocols are also supported, where the plate gradually cools from 25°C to 0°C, enabling determination of the cold withdrawal threshold—the temperature at which the first nocifensive response occurs—for detailed characterization of cold allodynia severity.