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. Author manuscript; available in PMC: 2012 Nov 1.
Published in final edited form as: Nat Neurosci. 2012 Mar 25;15(5):793–802. doi: 10.1038/nn.3078

Figure 2.

Figure 2

Photostimulation of pyramidal neurons in cortical slices of Emx1-Cre;Ai27 (abbreviated as E-Ai27), Emx1-Cre;Ai32 (E-Ai32), and Ai32 alone (-Cre) mice. (a) A barrel cortex slice with the 8 × 16 photostimulation grid overlaid (blue dots; spacing 50 μm). Scale bar, 200 μm. (b) Schematic of the photostimulation geometry and example traces. Whole-cell voltage-clamp traces from the dashed box area (left) are shown for E-Ai27 (with 840 μW light), E-Ai32 (70 μW) and Ai32 (1490 μW). Triangles, soma locations. (c) Waveforms of APs evoked by photoactivating the somata and dendrites (magenta) and axons (black). The arrow marks the inflection point. (d) Whole-cell current-clamp traces showing evoked APs in the 8 × 16 grid for a typical cell each of E-Ai27 (1700 μW), E-Ai32 (155 μW), Ai32 (1500 μW), and IUE (155 μW). (e) Minimum laser power required to evoke an AP from at least one stimulation site. (f) Number of photostimulation sites evoking an AP as a function of laser power in E-Ai32 neurons (n = 7). (g) Number of stimulation sites triggering APs using high laser powers. (h) Spike latencies of somatic/dendritic APs from the light onset. E-Ai32h: E-Ai32 cells (n = 9 cells, 143 APs) under high powers (≥1 mW). E-Ai32l: E-Ai32 cells (n = 9 cells, 28 APs) under low powers (≤100 μW). E-Ai27: E-Ai27 cells (n = 2 cells, 4 APs) under high powers. Spike latencies of axonal APs (not shown) varied greatly. (i) Number of stimulation sites triggering APs using low laser powers.