The catalepsy test: its ups and downs

The typical catalepsy test consists of placing an animal into an unusual posture and recording the time taken to correct this posture. This time is regarded as an index of the intensity of catalepsy. Catalepsy is a robust behavior, and the lack of standardization does not usually hinder its actual detection. However, the intensity of the cataleptic effect is influenced by minor methodological differences, and thus interpretation and comparison of results across laboratories are difficult. The behavioral catalepsy test can use any of several different apparatus, including wire grids, parallel bars, platforms, or pegs, to situate the animals in unusual positions. The most common, however, is the "bar test," and despite its wide use in psychopharmacological research, even parameters of this test are not standardized. The present article reviews the wide variety of parameters chosen by investigators that measure catalepsy. The methodological issues of repeated testing, scaling of scores, apparatus, animal weight, maximal test duration, behavioral criteria, and other influences are discussed. In addition, a brief review of the neuropharmacological basis of catalepsy is also included. Finally, it is argued that a universal, standardized bar test be adopted by researchers. New data on a novel automated bar test in the Digiscan Activity Monitoring System is presented.