Fig. 7: Electrophysiological measurements.

Visually evoked potential (VEP) measurements in RCS rats (n = 4 per group) were performed by a full-field illumination (A) and alternating grating patterns (B) projected onto the reimplanted MP devices (scale bars 500 µm). C Representative waveforms for the full-field stimulation using 10 ms pulses at 2 Hz with varying light intensities. Above the threshold, the characteristic VEP peaks appear (red asterisks). D Example waveforms of a response to alternating gratings (red asterisk). E Peak-to-peak VEP amplitude as a function of irradiance for a primary implanted MP 22 µm (blue) and a reimplanted MP 22 µm device (red). VEP signal above noise (dotted black line) was observed at 0.06 mW/mm² in both measurements. F VEP amplitude as a function of the grating bar width for primary implanted and reimplanted MP 22 µm devices. Acuity limit defined as the point where the log fit crosses the noise level (26 and 28 µm, respectively). The error bars represent the standard error of mean (SEM). Each group had 7 biologically independent subjects. The black dash lines represent the mean noise level; red and blue lines are logarithmic fit and the bands around them represent the 95% confidence interval.