Fig. 3: Data analysis of recorded neural signals in response to electrical stimulation.

a Representative raw recordings after an electrical stimulation with a 4-msec-long 50 μA biphasic pulse. b Magnified views of a raw recording before (upper) and after (lower) electrical artifact reduction. c Preprocessed recordings from the electrode adjacent to the stimulating electrode (corresponding to the region marked by the purple dashed circle in a). d Spike waveforms of detected neurons from different electrodes (C1–C8). Gray traces indicate overlays of spike waveforms, and each red trace represents the average spike waveform in a given cell. e Raster plots from all recorded cells without (top, red) and with (bottom, blue) local ground activation. An identical electric stimulus (4-msec-long 100 μA biphasic pulse) was repeated 10 times; stimulus onset timings are marked with vertical red dashed lines. Each black tick represents an individual spike. The assigned cell numbers reflect their distance from the stimulating electrode; smaller numbers denote cells closer to the stimulation site, whereas large numbers represent cells farther away. Cell numbering is consistent between the two without and with local ground conditions. f Enlarged raster plots corresponding to the region highlighted by the bold box in (e), with the time scale expanded for clearer visualization for 1 sec, the duration of recordings after each of the 10 repeated stimuli