Figure 6.

Single trial event-related potential (ERP) projection using t-Distributed Stochastic Neighbor Embedding (t-SNE). t-SNE projects multi-dimensional datasets into a lower dimensional space for visualization. A high dimensional 654 (98 infrequent stimuli + 556 frequent stimuli) × 12224 (64 electrodes × 191 time-point) matrix of single trial ERP’s was projected to two dimensions using t-SNE (single healthy subject) in (A). The single-trial ERP responses to infrequent auditory oddball stimuli (in red) reasonably separate from the single-trial ERP responses to frequent auditory stimuli (in black), motivating the use of t-SNE for visualizing multi-electrode single-trial ERP’s. The separation between frequent and infrequent stimuli was quantified as the average Euclidian distance between frequent and infrequent stimuli minus the average distance among infrequent and infrequent stimuli. A boxplot of the distribution of differences is indicated in (B) for healthy controls (HC) and patients with schizophrenia (SZ). These results indicate a better separation among frequent and infrequent stimuli among HC than SZ (bootstrap test; p < 0.001; modified from Bridwell et al., 2018).