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. Author manuscript; available in PMC: 2017 Mar 2.
Published in final edited form as: Neuron. 2016 Feb 18;89(5):1031–1045. doi: 10.1016/j.neuron.2016.01.027

Figure 3. Optogenetic activation of A1 axons in V1.

Figure 3

(A) Retrograde labeling. Left, CTb-Alexa 488 (green) injection site in V1 of a Rbp4-Cre::tdTomato (red) mouse. Middle, retrogradely labeled neurons in A1. Right, tdTomato expression pattern in A1. Scale bars, 200 μm.

(B) Anterograde labeling. Left, AAV-DIO-hChR2-eYFP injection site in A1 (outlined by two dash lines) of a Rbp4-Cre mouse. Scale bar, 250 μm. Middle, A1 axons in V1 of the same animal. Scale bar, 200 μm. Right, example local field currents recorded in superficial layers of V1 without (upper, trigger only) and with (lower) LED illumination (duration = 50 ms, onset marked by the arrow). Scale: 20 pA, 100 ms.

(C) Top, PSTHs for spike responses of an example L2/3 pyramidal neuron to gratings at a high (95%) contrast, without (left) and with (right) LED illumination. Scale: 70 Hz, 500 ms. Bottom, average normalized evoked firing rate (FR) at different orientations (relative to the preferred) for all the recorded L2/3 cells. Inset, polar graph plotting (inset) for the cell shown in top. Red, visual stimulation only; blue, visual plus LED stimulation.

(D-F) Plots of evoked firing rate at the preferred (D) and orthogonal (E) orientation, as well as of gOSI (F) in the LED-on versus LED-off conditions for all the cells (n = 18). Insets, mean normalized evoked firing rates (D, E) and mean gOSI values (F) of all the cells. *, p < 0.05; **, p < 0.01; ***, p < 0.001, paired t-test (D, E) or Wilcoxon signed-rank test (F). Error bar = SEM (D, E) or SD (F).

(G) The same cell as in (C), except that visual stimuli were at a low (25%) contrast. Scale: 60 Hz, 500 ms.

(H-J) Responses under low contrast stimuli. Data are presented in similar manners as in (D-F) (n = 18). **, p < 0.01; ***, p < 0.001, Wilcoxon signed-rank test (H) or paired t-test (I, J).

(K-N) Responses of L4 neurons to high contrast stimuli (n = 20 cells). Data are presented in similar manners as in (C-F). Scale in (K): 80 Hz, 500 ms. “n.s”, nonsignificant, p > 0.05, Wilcoxon signed-rank test (L, M) or paired t-test (N).

(O-R) Responses of L4 neurons to low contrast visual stimuli (n = 20 cells). Scale in (O): 80 Hz, 500 ms.