Fig. 1: The two timescales of hippocampal assemblies.

a Maze and task schematic. Task trials constitute choice and guided runs. In choice runs, the animal runs in direction G → C, deciding between left or right turns at the T-junction marked in gray. The correct choice is contingent upon the starting ___location. In guided trials, the animal runs in direction C → G, following a predetermined path guided by motorized moveable doors; b The distribution of the temporal precision of the assemblies detected during the spatial working memory task shows the presence of two predominant timescales: one peaked around 28 ms and one on the second scale. Bars show weighted mean and SE computed across six animals and four sessions (sessions without assemblies were excluded, n. sessions = 22, n. assembly pairs = 4914). The mean is weighted by the number of place cells recorded in each session. See Supplementary Fig. 4 for the same analysis on assemblies detected excluding spikes fired during SWR; c Assembly-assignment matrix for one exemplary dataset. The grayscale indicates the temporal resolution at which assemblies are detected; the color scale shows the lag between the activation of each assembly unit with respect to the unit first active in the assembly. Units marked in dark blue (lag of 0) are the first to activate within the assembly, and units marked in dark red are the last (two bins after the activation of the first assembly unit). Hippocampal place cell units were typically found taking part in multiple assemblies; d, e Examples of spike- (d) and rate- (e) assembly activity patterns (red) and raw LFP. Temporal resolution, composing units, and lag of activation of each unit with respect to the activation of the first assembly unit are indicated in the figure. Spike-assembly activations appear to be locked to the theta rhythm of the LFP; f, g Example of spike- (f) and rate- (g) assembly activation maps (activity normalized to 1, unit number indicated with respect to the relative session). See also Supplementary Fig. 3 for place fields of the relative assembly composing units. Source data are provided as a Source Data file.