Neurons are selected for study with voltage sensitive dye according to the intactness of their axonal arbors and the nearness of the axons to the surface of the slice, as observed with the confocal microscope
Figure 2. By imaging and choosing a cell that is intact and in which the axon is near the surface of the slice, we are able to greatly increase efficiency of the VSD experiment. The image on the right is typical for the VSD camera. Pixel size in the VSD camera is 4 microns square in our recording arrangement.