Fig. 3

Intrinsic optical signal imaging of the visual cortex from visual stimuli. Experimental diagram (A). Four displays for producing visual stimuli were placed around the rat, and a speaker for auditory stimuli was set at each ear. The rat was fixed in a holding box, and a camera acquiring images of the surface of the visual cortex was placed above its head. A view of the visual stimulus experiment (B). Example of cortex surface image used in this experiment (C). The white-dashed line shows the sagittal suture. This area is 6–9 mm behind the bregma and 6 mm left or right from the sagittal suture. A photograph of a transcranial observation of the visual cortex after surgery (D). Visual stimulation formed sine-waved stripes presented on four displays covering the entire field of view. Averaged waveform (red line) calculated from all trials (grey lines) stimulating a full field of view in a Royal College of Surgery (RCS) (+/+) rat and an RCS (rdy/rdy) rat are shown in (E) and (H), respectively. In (E) and (H), the vertical and horizontal axes indicate the changes in green-reflected light and the time course, respectively. The black arrow indicates the visual stimulus. Typical response area map of the visual cortex stimulating a full field of view in an RCS (+/+) rat (F) and an RCS (rdy/rdy) rat (I). Typical response area map of the visual cortex stimulating only the left eye in an RCS (+/+) rat (G) and an RCS (rdy/rdy) rat (J). The black-dashed lines in the heatmap (F, H, I, and J) indicate the sagittal suture in each image. All data analyses were performed using Python. X and Y mean coordinates of the pixel (1 pixel = 0.04 mm). The vertical axis of (F) and (G) and the units of the coloured bars in (I) and (J) are %. The heatmaps were made of reflectance changes from a visual cortex during stimulation.