Extended Data Fig. 10: Validation of convNMF on simulated CA3 replay sequences.
From: Adaptive stimulus selection for consolidation in the hippocampus
a, Randomly, recurrently-connected spiking network model (pyramidal cells, blue triangles; interneurons, red circles) of CA3 used to generate synthetic replay sequences (Methods). b, Replay occurs spontaneously at rest in the simulated CA3 network (n=8000 simulated pyramidal cells, 150 inhibitory interneurons): 10 s simulation epoch, sampled at 10 kHz. Cell x time raster. c, Simulated spike rasters from (b) are re-binned to the calcium sampling rate (30 Hz). d, Re-binned spikes are then convolved with a calcium kernel (tau=0.65 s), with added white Gaussian noise to simulate experimental conditions. e, Schematic of convNMF technique used to detect sequential reactivation events, vs standard NMF (Methods). The convNMF approximates the cell x time raster as the sum of K matrices, each which can be decomposed into the convolution of a rank-1 temporal component with cell x lag matrix. Unlike standard NMF, convNMF extracts recurring, localized sequential activity patterns. f, High-fidelity reconstruction of the simulated replay/calcium dataset in (b) is achieved using the convNMF-identified replay ensembles (left panels) and temporal factors (top traces). Each cell-component (left panel) represents a recurring sequential pattern of cell activations detected in the network. g, Slopes and intercepts were calculated for inferred replay events which were then compared to ground truth. ConvNMF accurately identifies replay events and extracted sequences of replaying cells. Left, scatterplot of true (x-axis) vs inferred (y-axis) replay slopes (a.u.). Note that this simulation also demonstrates that forward and reverse replay events are reliably differentiated by convNMF. Right, distribution of true (x-axis) vs inferred (y-axis) replay intercepts. h, ROC curve of sensitivity/specificity of replay event detection by convNMF. Specificity is prioritized over sensitivity. 20-60% of “true” replay events were detected at an 80% specificity threshold.
