Fig. 5 | Nature Communications

Fig. 5

From: Deep 2-photon imaging and artifact-free optogenetics through transparent graphene microelectrode arrays

Fig. 5

Measurement of optogenetic photostimulation-induced electrical potentials in Thy1-ChR2 mice that express channelrhodopsin-2 (ChR2) in layer-V pyramidal neurons. a A 473 nm laser beam (diameter: 210 µm full-width half-maximum) was sent through a 20× objective next to one graphene electrode (highlighted in gray). Different illumination times (1, 5, and 10 ms) and powers (0.5, 1, and 2 mW) were used. Heatmaps represent maximal response amplitude of the 16 electrodes in the array; example traces are shown for 0.5 mW/1 ms (top left) and 2 mW/10 ms (bottom right). b Two-photon image of the illumination target after intravascular injection of FITC-dextran (2 MDa); the yellow outline indicates the position of the graphene electrode. Scale bar, 100 µm. c Per condition, illumination with the 473 nm laser beam was targeted to 12 sites “on substrate” (circles with broken lines) and to four sites “on graphene” (circles with closed lines) where the laser beam directly irradiates part of the electrode (yellow outline). d Electrical response of the single graphene electrode within the illumination target in a live Thy1-ChR2 mouse (“Thy1-ChR2”), in the same animal after death (“post mortem”), and in vitro on an agarose phantom (“on phantom”). Laser pulses of 1, 5, and 10 ms length with powers of (0.5, 1, 2, and 7 mW) were used. Average responses of 12 “on substrate” or 4 “on graphene” illuminations per condition are shown; averaged responses from “on substrate” illuminations were used for response amplitude comparison across the microelectrode array as shown in a

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