Fig. 1.
VSD responses to sensory stimulation can be imaged by two-photon microscopy. (a) Combined in vivo setup for intrinsic and two-photon imaging. (b) Superposition of a reflected-light image of the surface vasculature and barrel positions (blue, C1; magenta, C2; green, C3). Colored areas show where reflectivity changes were >0.1% in response to whisker deflection. White line, line scan position and length during two-photon imaging. (c) Averaged (n = 400 trials) dye responses to whisker stimulation for focal depths of 40, 200, and 400 μm at an excitation wavelength of 1,020 nm. Dashed line, onset of stimulation of C2, the principal whisker for the line scan position. Red, fits of α function. (d–f) VSD signal amplitude in units of ΔF/F (d), latency (e), and decay (f) as a function of depth (n = 4 mice). (g) VSD signal for 960- and 1,020-nm excitation at a depth of 80 μm under identical stimulus conditions (200 trials).