A simple and effective method for building inexpensive infrared equipment used to monitor animal locomotion.

Background: Infrared (IR) technology is a flexible and effective way of measuring animal locomotion. However, the cost of most commercial IR equipment can limit their availability. We have designed an inexpensive and effective replacement for commercial IR sensors that can be attached to enclosures to monitor animal locomotion.

New Method: IR components were soldered to circuits connected to a single microcontroller. These IR components were housed inexpensively using plastic tubing and cork discs to further focus and extend detection of the IR beam. A standard personal computer recorded data from circuit boards connected to an inexpensive interface. This system may be used in a range of lighting conditions without requiring readjustment or recalibration.

Results: Validation of our equipment design was done with male Sprague Dawley rats treated with reserpine 22h prior to administration of saline or l-DOPA (125mg/kg). Data was collected in eight different measures: horizontal activity, immobile time, elevated activity, centre elevated activity, elevation time, elevation bout, and repeated and non-repeated movement while elevated. l-DOPA increased horizontal movement and all elevated activity excepting elevated movement and centre elevated movement, demonstrating selective drug effects.

Comparison With Existing Methods: The total cost of our complete IR system (US$517.45) was substantially less than the least expensive quote (US$19,666.90) obtained for a commercial IR system.

Conclusions: We have successfully designed and constructed a flexible and inexpensive IR system to monitor at least eight measures of rodent locomotion at a significantly lesser cost than quoted by commercial suppliers.