A simple computer-aided device for monitoring activity of small mammals and insects

Abstract

A simple computer-aided device was developed to record the activity of small animals. The device comprises of aktographs, opto-couplers, opto-amplifier units, a data acquisition unit ('Activity Monitor') and a Pentium processor based personal computer (PC) attached to an addition parallel printer port. The aktographs are devices which facilitate organisms to exhibit its natural activity. The aktographs for fruit flies, ants and mice are tubes with food supply and moisture, petri dishes adequately ventilated with arrangements for constant supply of water, sugar or honey solution, and cages attached with running wheels, respectively. Two mutually perpendicular beams of infra-red (IR) emission form a cross-hair detection system across the aktographs and an interruption to these beams creates an electrical signal ('transition') which is amplified using the opto-amplifier unit and sent to the activity monitor which consists of shift registers. The number of moments the IR beams are interrupted is taken as a measure of the amount of activity, based on the assumption that a more active animal would interrupt the IR beams more often compared to a less active one. Programs were written in C++, which facilitated data acquisition and graphical representation in terms of a daily plot of amount of activity as a function of time of the day, and actograms of daily activity were arranged chronologically one below the other. The activity patterns of individual animals (fruit fly, ants, and mice) were monitored using this device. Based on the performance and features of this device, we feel that with some improvement in the software this can substitute some of the existing activity recording devices, which are costly and not flexible.