Supplementary Figure 2: oPSD induced greater Ca²⁺ transients in distal dendrites than iPSD.

AAV-GCaMP6s and AAV-C1V1-eYFP were co-infused into the DMS, and whole-cell current-clamp recordings were conducted in C1V1-expressing neurons. A 2-sec step current was injected through the patch pipette, and 1-sec light stimulation (590 nm) was delivered through the objective lens. (a) Sample whole-cell recording showing action potentials elicited by iPSD or oPSD. Note that iPSD-induced a train of spikes, whereas oPSD induced a few spikes, which may be due to depolarization block¹. (b) Representative traces of dendritic Ca²⁺ transients induced by iPSD (left) or by oPSD (right). (c) oPSD induced significantly greater Ca²⁺ transients in the distal dendrites than did iPSD. Left, comparison of dendritic Ca²⁺ transients induced by iPSD and oPSD. t₍₁₃₎ = -3.34, **P = 0.0054. Right, comparison of normalized dendritic Ca²⁺ transients to the somatic ones. t₍₁₃₎ = -3.15, **P = 0.0077; Two-sided unpaired t test. n = 8 neurons, 5 rats (iPSD) and 7 neurons, 3 rats (oPSD). Data are presented as mean ± s.e.m. ¹Kleinlogel, S. et al. Ultra light-sensitive and fast neuronal activation with the Ca²⁺-permeable channelrhodopsin CatCh. Nat Neurosci 14, 513-518 (2011).