Supplementary Figure 7: Spatial resolution of 488 nm confocal laser scanning of the AIS in MSO cells pre-incubated in 300 µM AAQ.

(a) AIS of an MSO principal neuron filled with 40 µM Alexa Fluor 568 hydrazide. A series of four 30 µm long regions of interest (yellow box) were drawn, first over the AIS, and then laterally offset from the AIS in 0.5 µm increments (only the two extreme positions of the ROIs are shown for clarity). (b) Cells were held constantly in 380 nm field illumination to maintain AAQ in the unblocked configuration. Each ROI was then scanned at 488 nm, and the change in resting potential was measured. Cells were returned to the 380 nm condition after each scan. The change in membrane potential fell exponentially with distance from the AIS and exhibited a distance constant of 0.37 µm, demonstrating that the compartment-specific effects of AAQ blockade are minimally affected by light scattering in the slice. Scale bar, 10 µm.