Appropriateness of kaolin consumption as an index of motion sickness in the rat.

The appropriateness of kaolin consumption, one form of pica, as an index of motion sickness in the rat was examined. Unlike other motion sickness indices, the use of kaolin consumption results in a bitonic function across daily rotation sessions. This bitonic function is not predicted from any theory of motion sickness (viz., the Sensory Rearrangement Theory), rather an inverse relationship should exist between the severity of motion sickness and repeated exposure to the effective motion (i.e., habituation). The results of Experiments 1 and 2 support the continued use of kaolin consumption as an index of motion sickness in the rat. A response interference process is proposed to account for the first portion of the bitonic kaolin consumption function with grooming possibly representing a higher probability behavior than kaolin consumption. Experiment 3 examined and confirmed that kaolin consumption indexes the process of rehabituation to an effective motion. This extends the number of principles that are characteristic of motion sickness exhibited by species capable of emesis and supports the continued use of kaolin consumption as an index of motion sickness and general gastrointestinal malaise in the rat.