Fig. 8. In vivo calcium imaging of visual cortical neuron activity.

a Upper row: left, a recording chamber placed over the V1 and V2 in Monkey H; Central, six loci of AAV2.1-A vector (AAV2.1-A-CaMKIIα-GCaMP6s) injections (denoted by open circles). lu, lunate sulcus; Right, intrinsic signal optical imaging (ISOI) for visualizing an orientation map of the visual cortex at 237 days post-injection. Middle row: One-photon wide-field calcium imaging (WFCI). Left, vector injection sites at 237 days post-injection visualized by selecting the maximum fluorescence changes (ΔF/F) for each pixel across all stimulus conditions; Central & Right, orientation maps visualized at 69- and 237 days post-injection. The color code indicates the preferred orientation determined for each pixel. Note that these maps are basically consistent with the one obtained from ISOI (see the upper right) and, also, at the two-time points apart ~6 months. Lower row: Two-photon calcium imaging (TPCI). Left, structural image of the recording sites at 244 days post-injection obtained by averaging the fluorescence across all frames for a recording session. Central & Right, orientation maps at the single-neuron resolution at 41- and 244 days post-injection. The color code represents the preferred orientation determined for each neuron. b Time-dependent changes (ΔF/F) in fluorescent signals obtained from 14 exemplified neurons in the V1 recorded at 41 and 244 days after the vector injection. These calcium transients were recorded in response to visual stimuli. c Responses of fluorescent signals of two V1 neurons (Neurons A and B) to drifting gratings of different orientations. The responses to the same orientation with opposite moving directions are superimposed. (Insets) Arrowheads point to the imaged neurons with the typical nucleus-empty appearance of GCaMP labeling. Data were obtained in Monkey H. Scale bars, 20 µm.