Assessing bPAC function in hippocampal neurons. a, CA1 pyramidal cell expressing bPAC, CNG-A2, and RFP (two-photon imaging at 980 nm; scale bar, 30 μm). b, light-evoked cAMP-gated current at 0.14 milliwatt/mm (2). Arrow, 100-ms light pulse. The enlarged inset shows miniature excitatory postsynaptic currents. c, light-evoked cAMP-gated currents in one pyramidal cell at four different light doses (black traces, 0.14 milliwatt/mm2 for 50, 100, and 1000 ms; gray traces, 109 milliwatts/mm2 for 1 s). Traces were low pass-filtered at 10 Hz to remove miniature excitatory postsynaptic currents. At all stimulation intensities, currents were fully reversible and highly reproducible. CNG currents saturated at 0.14 milliwatt × s mm−2. d, light-evoked cAMP-gated currents before and after forskolin (100 μm) + IBMX (100 μm) wash-in. During forskolin/IBMX wash-in (dashed line, 5 min), holding current increased from −108 pA to −446 pA. Forskolin/IBMX application only partially occluded light-induced currents.