Article Figures & Data
Figures
- Figure 1.
Line-scan recording of Vm with SHG during voltage steps in cultured Aplysia neurons. A, Projection image superimposing 21 ∼1-μm-thick z-sections 2 μm apart. B, A single z-section through the neuron in A at the plane of line scanning. The green line represents the scanned line where membrane potentials are recorded. C, SHG signal changes recorded by line scanning the line denoted in B at 600 lines/sec. The voltage-clamped neuron was given a 240 msec duration –100 mV step after 80 msec of scanning during each line scan. n = 50 line scans were averaged. The line scan image is scaled to visualize the small change in SHG emission. Calibration: 50 μm, 50 msec. D, The green trace, obtained from the left membrane line in C, is a normalized intensity plot of SHG emission versus time. The red line represents the measured Vm during the voltage-clamp step. a.u., Arbitrary units. E, Plot of ΔSHG/SHG over physiologically relevant ΔVm. The functional fit in red shows a linear relationship. Error bars represent SDs of three to five different measurements at each ΔVm ±∼4 mV. Note the inverse relationship between ΔSHG/SHG and ΔVm.
- Figure 2.
Fast SHG line-scan recording of APs at multiple sites in cultured Aplysia neurons. A, An SHG projection image of six ∼1-μm-thick z-sections 3 μm apart. Green lines represent the scanned lines. Scale bar, 50 μm. B, C, The green traces, obtained from the averaged line scans, are normalized intensity plots of SHG emission versus time at membrane position 1 and position 2, respectively, in A at 1200 lines/sec (0.833 msec/line). Two APs were elicited by current injection (timing of current pulses given by black arrowheads), one at 45 msec and the other at 170 msec, during each line scan. n = 50 line scans were averaged. The red trace is the Vm from the recording electrode at the soma. The inset is an expanded time base around the AP in the blue dashed box. C reveals the usefulness of high-resolution optical Vm recording by showing the clear difference in AP duration that can occur between the soma and neurites of individual neurons. D, Example of shorter APs from a different neuron than in A. n = 70 line scans were averaged.
