Figure 4
In vivo iEEG recording results from transcutaneous and subcutaneous stimulation. Comparison of transcutaneous and subcutaneous stimulation on the iEEG of a beagle. (A) Representative spectral power changes after transcutaneous (red line) and subcutaneous stimulation (blue line) in a frontal electrode cluster (postwave–prewave changes calculated with using a Hamming window with 50% overlap). PSD change between pre-stim and post-stim period was compared for different frequency bands (2–30 Hz, resolution of 2 Hz bins). (B) P-values show the difference in PSD changes between TES, SES, and baseline (n = 4, paired t-test). Skull-applied current induced iEEG changes in alpha and beta waves in contrast to scalp-applied current. (C) Changes in power in the frequency bands from delta to beta with varying stimulus intensity (mean ± CI, n = 64). SES induced PSD changes more than twice that of TES and baseline signal, largely independent of stimulus intensity. Asterisks code for significance (*, P < 0.01; +, P < 0.01 t-test with baseline signal). Delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), and beta (13–30 Hz).
