Fig. 6 | Nature Communications

Fig. 6

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

Fig. 6

Measurement of vascular responses to optogenetic (OG) photostimulation below graphene microelectrode arrays in Thy1-ChR2 mice. a Location of diving arterioles for diameter measurements with 2-photon imaging as shown in b, c. Yellow outlines indicate single graphene electrodes. Data was acquired after intravascular injection of FITC-dextran (2 MDa). Scale bar, 500 µm. b Line-scan mode was used to measure time courses of single arteriole diameters; blue arrows indicate when a 473 nm laser stimulus was delivered, red lines indicate computed vessel borders used for estimation of diameter changes. c High-magnification scans of arteriole segments are shown on the left (scale bars: 50 µm); red arrows indicate line scan location. Vascular responses (diameter change relative to pre-stimulus baseline, Δd/d) averaged from five to six photostimulation events (indicated by blue arrow) are shown in the middle; respective electrical responses to photostimulation measured with the graphene array are shown on the right. Note that stimulus intensities and illumination times used to elicit detectable vascular responses (50–100 ms at 7 mW) are larger than photostimulation shown in Fig. 5. Control experiment with a ChR2-negative animal is shown in Supplementary Fig. 10

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