Figure 6.

Amplification of Weak Basal Inputs Is Blocked by Intracellular Application of QX-314

(A) Biocytin reconstruction of example cell from basal dendrite optogenetic stimulation experiment, showing the apical (green) and basal (orange) dendrite, the axon (gray, truncated), and the optogenetic stimulation spot (cyan arrow). Inset shows in vivo image of Alexa-Fluor-594-filled dendrite in red and optogenetic stimulation site in cyan.

(B) Both large- and small-amplitude mean example OP_bas show a reduction in amplitude from V_hyp (blue) to V_dep (red) during whole-cell recordings with 1 mM QX-314 in intracellular solution.

(C) Population mean OP_bas during intracellular QX-314 application is reduced in V_dep.

(D) V_m increase as neurons transition from V_hyp to V_dep during experiments using intracellular QX-314. Gray lines show data from individual cells, filled circles with error bars the mean ± SD.

(E) A significant reduction of OP_bas amplitude in V_dep compared to V_hyp.

(F) OP_bas half width is significantly smaller in V_dep in comparison with V_hyp.

(G) No correlation between state modulation of OP_bas amplitude and the log₁₀ of V_hyp OP amplitude during QX-314 application (blue); significant correlation during MK-801 (light green) and D-890 (light orange) application. Open circles represent mean response from a single cell, blue line shows linear fit, and green and orange lines single exponential fit.

(H) The ratios of the V_dep:V_hyp amplitude for small-amplitude OP_bas (<0.4 mV) are significantly different during intracellular QX-314 application, but not during MK-801 or D-890. Gray open circles show data from single cells; bars show mean ± SD.