Figure 3.

Evaluation methods of neural function using Drosophila. (A) Climbing assay. It is a measurement of motor function taking advantage of the fly’s negative geotaxis. (B) Olfactory memory assay using T-maze. At the training phase, unconditioned stimulus (US) such as electric shock and sweetness such as sucrose is associated with the odour in the training tube. Next, another odour is presented, without US. In the test phase, the two odours used in the training are presented to the trained fly from both ends of the test tube, and the performance index is quantified by which odour attracted the fly. In the figure, the associative learning between odour A and electric shock, called aversive learning, leads to the learning flies avoiding odour A. (C) Schematic diagrams of Actogram. Actogram is a double-plotted graphical representation of the phases of an organism’s daily activity and resting time. Grey shading indicates the dark phase. In controls, the level of activity increases in the morning and evening, but when the circadian rhythm is disrupted by the expression of disease gene, this time-specific increase is not observed. (D) Schematic diagrams of ERG trace. In healthy flies (left panel), the ERG traces are derived from photoreceptor activity (depolarisation and repolarisation, white arrow heads in the figure) and from postsynaptic neuron activity (on-transient and off-transient, black arrow heads in the figure). When the pathological gene is expressed, the ERG trace can be used to estimate what part of the visual system is impaired.