Fig. 1

Network construction and basic analysis. a 3D visualization of all surface electrodes included in our data set, colored by the Talairach atlas labels used in this article’s analysis. b Schematic of spectral phase approach that compares the distributions of phase differences between electrodes across all trials of the verbal free-recall task. Significantly tighter distributions indicate greater synchronization. c Connectivity maps were extracted for each of 294 neurosurgical patients, reflecting the connectivity change associated with successful item recall. Effects were pooled across subjects and ROIs to construct the final network. Blue indicates decreased phase synchrony associated with successful encoding, red indicates increased synchrony. d 74 × 74 ROI adjacency matrices representing the z-scored time-averaged and frequency-averaged connection weights during the item presentation interval (0–1600 ms). The high gamma network is constructed from frequencies between 45–100 Hz, and theta from 3–8 Hz. Node indices are organized by lobe per the indicators on the axes. Gray areas represent connections between ROIs with fewer than seven subjects’ worth of data. e 3D visualizations of the whole-brain HG and theta networks. f Summed positive and negative connection weights in each frequency band. In a remembered vs. not-remembered contrast, the total level of synchronous theta connections and asynchronous HG connections were significantly greater than chance (P < 0.01), and there was a significant frequency-synchrony interaction (P < 0.01, χ ² test). Dotted lines indicate mean chance level, shaded area ±1 STD