Fig. 1.

Effect of adding Poisson population spiking to a power law local field potential (LFP). A: power spectral density (PSD) of a summed Poisson spike train (10,000 neurons) is flat and increases as a function of firing rate (FR). B: robust linear fit (dashed lines) is applied to the sum of power law PSD and flat-spectrum signals from A and demonstrates flattening of slope as a result of increased FR, although the power law parameter χ remains unchanged. Colors correspond to firing rates in A. Inset: intersection frequency between fitted PSD and f⁻² decreases as FR (and broadband gamma power) increases.