Figure 1.

Response to Somatic Two-Photon Stimulation of ChR2-Expressing Layer 2/3 Pyramidal Neurons Is Reduced in Amplitude during Depolarized Phases of Slow Network Activity

(A) Schematic showing two-photon laser stimulation of ChR2-EYFP-expressing neurons.

(B) Example somatic membrane potential (V_m) recording of a layer 2/3 cortical pyramidal neuron under urethane anesthesia showing small depolarizations (optogenetic potentials [OPs]) in response to two-photon laser stimulation (cyan) during hyperpolarized (V_hyp, blue) and depolarized (V_dep, red) periods of network activity.

(C) Example in vivo image showing the path of the somatic laser stimulation (cyan).

(D) Overlaid, mean light-evoked OPs to somatic stimulation (OP_som, cyan) during V_hyp (blue) and V_dep (red) from two example neurons with different response amplitudes.

(E) Same as (C) but for population average.

(F) Somatic V_m increase as neurons transition from V_hyp to V_dep. Gray lines show data from individual cells, filled circles with error bars the mean ± SD.

(G) OP_som amplitude is significantly lower during V_dep than V_hyp.

(H) OP_som half width is significantly longer during V_dep than V_hyp.

(I) No significant correlation between the ratio V_dep:V_hyp OP_som amplitude and the log₁₀ of V_hyp OP_som amplitude in awake (purple) and anesthetized (black). Black and purple lines are linear fits.