Fig. 4.

Amplitude and relative timing of IIS-triggered dZ signals; data from the same recording as in Fig. 3. (A) (top) IISs at electrode with largest negative deflections (bottom left neighbour of electrode in Fig. 3), aligned by their negative peaks. Grey traces: individual IISs, thick black line: average IIS. (bottom) IIS-triggered dZ signal traces; each grey trace corresponds to the average measurement at an electrode and for a specific current injection configuration (n = 371 measurement combinations from 16 injection configurations). Blue circles indicate the minimum of each trace, and green circles indicate the first point reaching a significant positive value (p < 0.01, Student's t-test; n between 10 and 57 IISs for each trace). (B) Same data as in (A), but shown over a larger timescale. Red circles indicate the maximum of each trace. (C) Amplitude (top) and time (middle) distributions of the dZ signal minima (blue circles in (A)). (bottom) Distribution of the earliest time that dZ signals attain a positive value (green circles in (A)), expressed as onset time relative to the IIS peak. (D) Amplitude (top) and time (bottom) distributions of the dZ signal maxima (red circles in (B)). (E) Scatter plot between minimum and maximum amplitude of IIS-triggered dZ signal traces showing significant correlation (r =− 0.59, p < 0.01, n = 371).