Fig. 4.

Quantitative analyses of peak signal-to-background ratio for in vivo imaging of hippocampal neurons. (a) A cross-sectional (xy) image obtained from the hippocampal areas of young adult and adult mice. (b). In the upper panels, the signal and background peaks were calculated from fluorescence intensities in a line profile (20-μm diameter) across an individual neural process (signal: red line) and the background area (white line). The ratio R at each process was calculated by dividing the signal peak by the background (see Materials and Methods). The depth dependence of the average and Standard Error of the Mean of signal peak–to-background ratios (R) was calculated in young adult (a) and adult (b) mice. Red and black circles indicate averages obtained using the 1064-nm GSLD and 1000-nm Ti:Sa lasers, respectively (n = 7 processes; averages ± SEM).