A miniaturized video system for monitoring the locomotor activity of walking drosophila melanogaster in space and terrestrial settings

A novel method is presented for monitoring movement of Drosophila melanogaster (the fruit fly) in space. Transient fly movements were captured by a 60, 2.5-cm-cubed monochrome video camera imaging flies illuminated by a uniform light source. The video signal from this camera was bandpass filtered (0.310 Hz) and amplified by an analog circuit to extract the average light changes as a function of time. The raw activity signal output of this circuit was recorded on a computer and digitally processed to extract the fly movement events from the waveform. These events corresponded to flies entering and leaving the image and were used for extracting activity parameters such as interevent duration. The efficacy of the system in quantifying locomotor activity was evaluated by varying environmental temperature and measuring the activity level of the flies. The results of this experiment matched those reported in the literature.