Fig. 6.

Device implantation. (A) Photographs of a STACK device–implanted mouse. The device is implanted at the visual cortex (V1) of the mouse, and the needle electrode penetrates the area to record the visual responses. (B) Schematic representing the recording using an LED for the visual stimulation. (C, 1–4) Recorded signals via the implanted STACK device: average waveform of low-frequency band signals (filtering = 1 to 300 Hz, n = 100) (C, 1), high-frequency band-signal waveform from a single trial (filtering = 500 to 1,000 Hz) (C, 2), and the raster plot diagrams (C, 3) and PSTHs (C, 4). The detection threshold used was 3× the SD (σ) of the mean signal −0.5 to −1.0 s before stimulus onset. Asterisk denotes a significant spike; **P < 0.01, ***P < 0.005 (t test). (D) Immunohistochemistry of tissues in a mouse’s visual cortex (coronal section) 2 wk after implantation of STACK device (STACK) and without implantation (Control). Tissues were labeled for reactive astrocytes (GFAP). (E) Quantitative comparison of the tissues with and without the STACK device using fluorescent intensity in an area of 0.15 mm², taken from six slices of samples (t test, n.s.: not significant).