Figure 7.

Cluster structure of the bursty-grid-cell population. Dependence of key spike-train parameters on the amplitude of fast AHP (ΔV₁) and afterdepolarization (ΔV₂). For a definition of these two parameters, see, e.g., the caption of Figure 1. A, B, mean firing rates. C, D, Fraction of ISIs below 8 ms (“burstiness”). Across the entire population of bursty neurons, the larger ΔV₁, the more frequent are short ISIs. E, F, Location of ISI peak. While the firing rates do not exhibit a trend, neither within the two cell groups nor across the groups, the other quantities depicted show trends that differ from the null-hypothesis (no increase/decrease as a function of ΔV₁ or ΔV₂). The data also suggest that the population of bursty neurons either forms one joint although under-sampled cloud or contains two distinct subpopulations. In either case the spike-train characteristics do depend on the cells' DAP properties.