Fig. 2: Ultraslow oscillations are organized into oscillatory sequences.
From: Minute-scale oscillatory sequences in medial entorhinal cortex
a, Raster plot of calcium activity of all cells recorded in the example session shown in Fig. 1b (bin size = 129 ms, n = 484 cells). Time bins with calcium events are indicated with black dots; those without calcium events are indicated with white dots. Cells were sorted according to their correlation values with one arbitrary cell, in a descending manner. The example sequence indicated in red is 121 s long. b, As in a but now with neurons sorted according to the PCA method. c, Projection of neural activity of the session in a,b onto the first two principal components of PCA (left), and the first two dimensions of a Laplacian eigenmaps (LEM) analysis (right). Time is colour coded. One sequence is equivalent to one rotation along the ring-shaped manifold. d, Raster plot as in b. The phase of the oscillation, overlaid in red, was used to track the position of the population activity on the sequence. e, As in b, but showing the z-scored fluorescence calcium signals. f, Raster plot of binarized spiking activity of all units recorded in one example session using Neuropixels probes (bin size = 120 ms, n = 469 units). Neurons are sorted according to the PCA method. g, Distribution of sequence durations across 15 oscillatory sessions over 5 mice (imaging data only; one mouse did not have detectable sequences; 421 sequences in total). Each count is one sequence. h, Distribution of ISI (406 ISIs in total across 15 oscillatory sessions). Each count is an ISI. During periodic sequences the ISI is 0. Note that the y axis has a log scale.
