Researchers at the University of Guelph have created a low-cost automated apparatus for measuring catalepsy that increases measurement accuracy and reduces observer bias.
Catalepsy is a measure of muscular rigidity that can result from several factors including Parkinson’s disease, or pharmacological exposure to antipsychotics or cannabis. Catalepsy bar tests are widely used to measure this rigidity. The test consists of placing the arms of a rodent on a horizontal bar that has been raised off the ground and measuring the time it takes for the subject to remove themselves from this imposed posture. Traditionally, this has been measured by an experimenter with a stopwatch, or with prohibitively expensive commercial apparatus that have issues of their own. The automated bar test described here uses a 3D printed base with an Arduino operated design to make the design simple and affordable. This design sets itself apart by using extremely low-cost beam break sensors that avoid pitfalls of the traditional “complete the circuit” approach where changes in rat grip can result in false measurements. The beam break sensors to are used to determine whether the rat is on the bar or not and automatically measures and stores the time the rat takes to remove itself from the bar on an SD card for later retrieval. The device has been validated in rats; however, the bar height is adjustable so there is no reason it cannot be used in other rodents as well. This bar test thus makes catalepsy measures easy, accurate, and limits any experimenter bias due to manual measurements.