Fig 4. Examples of learned GP kernels.

A Left: inferred kernels K_t, K_e, K_s in the top, center, and bottom rows, respectively. Center: corresponding stationary auto-covariances from the Matérn(3/2) kernels (Eq 4). Right: corresponding unnormalized ‘gamma-like’ envelopes d_α,β (Eq 5). The inferred quantities are in agreement with what is observed in Fig 3B: first, the shape of temporal term d_α,β reflects that the artifact starts small, then the variance amplitude peaks at ∼.5 ms, and then decreases rapidly. Likewise, the corresponding spatial d_α,β indicates that the artifact variability induced by the stimulation is negligible for electrodes greater than 700 microns away from the stimulating electrode. B Same as A), but for the stimulating electrode. Only temporal kernels are shown, for two inter-breakpoint ranges (first and second rows, respectively).