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Relations between large-scale brain connectivity and effects of regional stimulation depend on collective dynamical state

Fig 4

Regional excitation causes local and downstream changes to brain areas’ power spectra in different frequency bands at WP1.

(A) Schematic of a brain network depicting the stimulated site i in brightest red. The black arrows point to two other regions j and k that lie at progressively further topological distances from the perturbed area in the structural network. In this figure, regions i, j, and k correspond to brain areas 1 (R–Lateral Orbitofrontal), 4 (R–Medial Orbitofrontal), and 10 (R–Precentral), respectively. (B) Left: A segment of region i’s activity time-course in the baseline condition. Right: A segment of region i’s activity time-course when it is stimulated. (C) Power spectra of area i and two other downstream regions j and k. In all three panels, the lighter curves correspond to the baseline condition, and the darker curves correspond to the state in which i is driven with additional input. The gray vertical lines indicate the peak frequency of region i in the excited condition. (D) Histogram of the shift in peak frequency induced by stimulating unit i, plotted over all choices of the perturbed area. (E) Distribution of peak frequencies of all units in the baseline condition (light gray) and distribution of the peak frequency units acquire when directly excited (dark gray). (F) Average power spectra 〈psd〉_j≠i over all units j ≠ i at baseline (light gray) and when unit i is perturbed with additional input (dark gray). (G) Average difference of the spectra of unit j ≠ i when unit i is excited and in the baseline condition, where the average is over all units j ≠ i. For reference, the light gray vertical lines denote the minimum and maximum peak frequency across units in the baseline state, and the dark gray line indicates the peak frequency acquired by the stimulated region i. Shaded boxes denote two frequency bands of interest: (1) the baseline band (purple) consisting of the main oscillation frequencies of brain areas under baseline conditions, and (2) the excited band (green) centered around the peak frequency that the stimulated region inherits. In subsequent analyses, we assess perturbation-induced changes in the PLV between brain areas in the baseline band, (purple), and in the excited band (green).

doi: https://doi.org/10.1371/journal.pcbi.1008144.g004